--- /dev/null
+/* (c) 2021 Aaron Taylor <ataylor at subgeniuskitty dot com> */
+/* See LICENSE.txt file for copyright and license details. */
+
+// TODO:
+// - Write a brief description of the machine being simulated. Only one thread, reduced RAM, no meaningful console when running as screensaver, etc.
+
+// CLI Flags:
+// -path-to-aout-binary
+// -path-to-font-file
+// -speed
+
+// Ideas for sample programs to include:
+// - Build list of integers on the stack (DUP, IM_1, ADD).
+// - Calculate prime numbers, placing them on the stack.
+// - Lights sliding back and forth, like PDP-11 front panel with some OSes.
+
+#include "screenhack.h"
+#include "simulator.h"
+
+/* Keep this source code C89 compliant per XScreensaver's instructions. */
+
+/* -------------------------------------------------------------------------- */
+/* Data Structures */
+/* -------------------------------------------------------------------------- */
+
+struct NEDsim {
+ /* Various X resources */
+ Display * dpy;
+ Window win;
+ GC gc;
+
+ // TODO: Explain these
+ int dpy_width, dpy_height;
+
+ // TODO: Explain that this is created during init, then lights are populated/overwritten on each frame.
+ Pixmap panel;
+
+ /* Delay (in microseconds) between clock cycles in the NED CPU. */
+ size_t delay;
+
+ int cell_size;
+ int border_size;
+ int origin_x_offset, origin_y_offset;
+ int num_data_rows;
+
+ size_t color_index;
+
+ Bool suitable_display;
+
+ char * current_font;
+
+ // TODO: Explain that this contains all the actual state of the NED machine being simulated.
+ struct NEDstate * nedstate;
+};
+
+struct color_rgb {
+ // TODO: Explain why this is an unsigned short. Copy from WolframAutomata.
+ unsigned short red, green, blue;
+};
+
+struct color_scheme {
+ // TODO: Explain all this.
+ struct color_rgb
+ panel_bg,
+ panel_fg,
+ light_on,
+ light_off,
+ error_on,
+ error_off,
+ primary,
+ secondary,
+ tertiary,
+ border,
+ text;
+};
+
+//static struct color_scheme color_list[] = {
+// // TODO: Explain all this.
+// // TODO: Add other color schemes, like purple PDP-11/70.
+// // TODO: http://www.chdickman.com/pdp8/DECcolors/
+// {
+// {63479,63479,63479}, // 092-XXXX-123
+// { 5140, 2056, 5654}, // 092-XXXX-152
+// {40092,11051,15677}, // 092-XXXX-139
+// {30326,13107,12850}, // 092-XXXX-154
+// {65535,13107,12850}, // homemade
+// {30326,13107,12850}, // 092-XXXX-154
+// { 4112,12850,20046}, // 092-XXXX-145
+// {12336,29555,37008}, // 092-XXXX-151
+// {30326,24158, 6425}, // 092-XXXX-157
+// {63479,63479,63479}, // 092-XXXX-123
+// {63479,63479,63479} // 092-XXXX-123
+// }
+//};
+
+static struct color_scheme color_list[] = {
+ // TODO: Explain all this.
+ // TODO: Add other color schemes, like purple PDP-11/70.
+ // TODO: http://www.chdickman.com/pdp8/DECcolors/
+ {
+ {63479,63479,63479}, // 092-XXXX-123
+ { 5140, 2056, 5654}, // 092-XXXX-152
+ {65535,11051,15677}, // 092-XXXX-139 - edit
+ {20000,13107,12850}, // 092-XXXX-154 - edit
+ {65535,13107,12850}, // homemade
+ {20000,13107,12850}, // 092-XXXX-154 - edit
+ { 4112,12850,20046}, // 092-XXXX-145
+ {12336,29555,37008}, // 092-XXXX-151
+ {30326,24158, 6425}, // 092-XXXX-157
+ {63479,63479,63479}, // 092-XXXX-123
+ {63479,63479,63479} // 092-XXXX-123
+ }
+};
+
+/* -------------------------------------------------------------------------- */
+/* Helper Functions */
+/* -------------------------------------------------------------------------- */
+
+// TODO: Explain
+static void
+set_color(struct NEDsim * nedsim, struct color_rgb * color)
+{
+ XColor temp;
+ XWindowAttributes xgwa;
+
+ XGetWindowAttributes(nedsim->dpy, nedsim->win, &xgwa);
+
+ temp.red = color->red;
+ temp.green = color->green;
+ temp.blue = color->blue;
+
+ XAllocColor(nedsim->dpy, xgwa.colormap, &temp);
+ XSetForeground(nedsim->dpy, nedsim->gc, temp.pixel);
+}
+
+// TODO: Explain
+// TODO: Make this a lot faster.
+// Input: size in 'cells', and sets font to fill that size, minus border and padding room.
+static void
+set_font_size(struct NEDsim * nedsim, int size)
+{
+ // vvv--- for border ---vvv vvv--- for padding ---vvv
+ int desired_height_in_pixels = (size * nedsim->cell_size) - (2 * nedsim->border_size) - (8 * nedsim->border_size);
+
+ const char * font_size_prefix = "-*-helvetica-*-r-*-*-";
+ const char * font_size_suffix = "-*-*-*-*-*-*-*";
+
+ size_t buffer_size = strlen(font_size_prefix) + strlen(font_size_suffix) + 100; // '100' since nobody needs font with size in 'points' greater than 100 decimal digits long.
+ char * font_full_name = malloc(buffer_size);
+ int font_size_in_points = 2; // Start with a 2 pt font and work our way up.
+
+ while (1) {
+ // Load the font.
+ snprintf(font_full_name, buffer_size, "%s%d%s", font_size_prefix, font_size_in_points, font_size_suffix);
+ XFontStruct * font = XLoadQueryFont(nedsim->dpy, font_full_name);
+ if (!font) {
+ printf("WARNING: Unable to load font %s. Probably gonna look wonky.\n", font_full_name);
+ font = XLoadQueryFont(nedsim->dpy, "fixed");
+ break;
+ }
+ XSetFont(nedsim->dpy, nedsim->gc, font->fid);
+
+ // Get the height.
+ int direction, ascent, descent;
+ XCharStruct overall;
+ XTextExtents(font, "X", 1, &direction, &ascent, &descent, &overall);
+
+ // Compare the height.
+ int height = overall.ascent - overall.descent;
+ if (height == desired_height_in_pixels) {
+ break;
+ } else if (height > desired_height_in_pixels) {
+ font_size_in_points--;
+ snprintf(font_full_name, buffer_size, "%s%d%s", font_size_prefix, font_size_in_points, font_size_suffix);
+ XFontStruct * font = XLoadQueryFont(nedsim->dpy, font_full_name);
+ if (!font) {
+ printf("WARNING: Unable to load font %s. Probably gonna look wonky.\n", font_full_name);
+ font = XLoadQueryFont(nedsim->dpy, "fixed");
+ break;
+ }
+ XSetFont(nedsim->dpy, nedsim->gc, font->fid);
+ break;
+ } else {
+ font_size_in_points++;
+ }
+ }
+
+ free(nedsim->current_font);
+ nedsim->current_font = font_full_name;
+}
+
+// TODO: Explain
+// TODO: Explain that this returns result in pixels so we can track fractional cell usage.
+static void
+get_text_size(struct NEDsim * nedsim, const char * text, int * x_size, int * y_size)
+{
+ int direction, ascent, descent;
+ XCharStruct overall;
+ XFontStruct * font = XLoadQueryFont(nedsim->dpy, nedsim->current_font);
+ XTextExtents(font, text, strlen(text), &direction, &ascent, &descent, &overall);
+ *x_size = overall.width;
+ *y_size = overall.ascent - overall.descent;
+}
+
+// TODO: Explain
+// TODO: Note that this might leave the foreground color changed.
+// Argument coordinates are in 'cells', not pixels.
+static void
+draw_rect_area(struct NEDsim * nedsim, size_t x_origin, size_t y_origin, size_t x_size, size_t y_size,
+ Bool bord_top, Bool bord_bottom, Bool bord_left, Bool bord_right)
+{
+ x_origin *= nedsim->cell_size;
+ x_origin += nedsim->origin_x_offset;
+ y_origin *= nedsim->cell_size;
+ y_origin += nedsim->origin_y_offset;
+ x_size *= nedsim->cell_size;
+ y_size *= nedsim->cell_size;
+ XFillRectangle(nedsim->dpy, nedsim->win, nedsim->gc, x_origin, y_origin, x_size, y_size);
+
+ set_color(nedsim, &color_list[nedsim->color_index].border);
+ if (bord_top) {
+ XFillRectangle(nedsim->dpy, nedsim->win, nedsim->gc, x_origin, y_origin, x_size, nedsim->border_size);
+ }
+ if (bord_bottom) {
+ XFillRectangle(nedsim->dpy, nedsim->win, nedsim->gc, x_origin, (y_origin + y_size - nedsim->border_size), x_size, nedsim->border_size);
+ }
+ if (bord_left) {
+ XFillRectangle(nedsim->dpy, nedsim->win, nedsim->gc, x_origin, y_origin, nedsim->border_size, y_size);
+ }
+ if (bord_right) {
+ XFillRectangle(nedsim->dpy, nedsim->win, nedsim->gc, (x_origin + x_size - nedsim->border_size), y_origin, nedsim->border_size, y_size);
+ }
+}
+
+// TODO: Explain
+// Arguments are in units of 'cells', not pixels.
+// Will leave foreground color changed.
+// Draws filled circle with upper left corner at x,y.
+static void
+draw_circular_area(struct NEDsim * nedsim, size_t x, size_t y, double diameter)
+{
+ // First, convert the function argument units from 'cells' to 'pixels'
+ x *= nedsim->cell_size;
+ y *= nedsim->cell_size;
+ diameter *= nedsim->cell_size;
+
+ // Add the panel's absolute x,y offset to the requested coordinates.
+ x += nedsim->origin_x_offset;
+ y += nedsim->origin_y_offset;
+
+ // Shrink the circle to be a bit smaller than the bounding box allows. Note
+ // that the three adjustment values must sum to 1.0.
+ // For example, 0.7 + 0.15 + 0.15 = 1.0.
+ x += (0.15 * diameter);
+ y += (0.15 * diameter);
+ diameter *= 0.7;
+
+ // Because we only draw the bottom border on repeated rows (e.g. draw_wordline()),
+ // we need to offset vertically by half a border height.
+ y -= (0.5 * nedsim->border_size);
+
+ // Start angle 0 and ending angle 360*64 is one full circle in Xlib units.
+ XFillArc(nedsim->dpy, nedsim->win, nedsim->gc, x, y, diameter, diameter, 0, 360*64);
+}
+
+// TODO: Explain
+static void
+draw_panel(struct NEDsim * nedsim)
+{
+// TODO: Collect all relevant #defines somewhere.
+#define OVERALL_WIDTH_IN_CELLS 70
+#define HEADER_HEIGHT_IN_CELLS 14
+#define FOOTER_HEIGHT_IN_CELLS 2
+
+ // Draw background color over entire window.
+ set_color(nedsim, &color_list[nedsim->color_index].panel_bg);
+ XFillRectangle(nedsim->dpy, nedsim->win, nedsim->gc, 0, 0, nedsim->dpy_width, nedsim->dpy_height);
+
+ // Draw NED panel in foreground color.
+ set_color(nedsim, &color_list[nedsim->color_index].panel_fg);
+ XFillRectangle(nedsim->dpy, nedsim->win, nedsim->gc,
+ nedsim->origin_x_offset,
+ nedsim->origin_y_offset,
+ nedsim->cell_size * OVERALL_WIDTH_IN_CELLS,
+ nedsim->cell_size * (HEADER_HEIGHT_IN_CELLS + nedsim->num_data_rows + FOOTER_HEIGHT_IN_CELLS)
+ );
+}
+
+// TODO: Explain
+static void
+draw_logo(struct NEDsim * nedsim)
+{
+#define LOGO_X_OFFSET 2
+#define LOGO_Y_OFFSET 2
+#define LOGO_WIDTH 20
+#define LOGO_NAME_HEIGHT 6
+#define LOGO_WEBSITE_HEIGHT 2
+
+ // First draw the two colored boxes that comprise the logo area.
+ set_color(nedsim, &color_list[nedsim->color_index].primary);
+ draw_rect_area(nedsim, LOGO_X_OFFSET, LOGO_Y_OFFSET, LOGO_WIDTH, LOGO_NAME_HEIGHT, True, True, False, False);
+ set_color(nedsim, &color_list[nedsim->color_index].tertiary);
+ draw_rect_area(nedsim, LOGO_X_OFFSET, LOGO_Y_OFFSET+LOGO_NAME_HEIGHT, LOGO_WIDTH, LOGO_WEBSITE_HEIGHT, False, True, False, False);
+
+ // Now draw the 'NED' text in the top box.
+ set_color(nedsim, &color_list[nedsim->color_index].text);
+ set_font_size(nedsim, LOGO_NAME_HEIGHT);
+ int text_x_size, text_y_size;
+ get_text_size(nedsim, "NED", &text_x_size, &text_y_size);
+ int local_x_offset = ((LOGO_WIDTH * nedsim->cell_size) - text_x_size) / 2;
+ int local_y_offset = ((LOGO_NAME_HEIGHT * nedsim->cell_size) - text_y_size) / 2;
+ XDrawString(nedsim->dpy, nedsim->win, nedsim->gc, (LOGO_X_OFFSET * nedsim->cell_size + nedsim->origin_x_offset + local_x_offset),
+ ((LOGO_Y_OFFSET+LOGO_NAME_HEIGHT) * nedsim->cell_size + nedsim->origin_y_offset - local_y_offset), "NED", 3);
+
+ // And draw the 'subgeniuskitty.com' text in the bottom box.
+ set_font_size(nedsim, LOGO_WEBSITE_HEIGHT);
+ get_text_size(nedsim, "subgeniuskitty.com", &text_x_size, &text_y_size);
+ local_x_offset = ((LOGO_WIDTH * nedsim->cell_size) - text_x_size) / 2;
+ local_y_offset = ((LOGO_WEBSITE_HEIGHT * nedsim->cell_size) - text_y_size) / 2;
+ XDrawString(nedsim->dpy, nedsim->win, nedsim->gc, (LOGO_X_OFFSET * nedsim->cell_size + nedsim->origin_x_offset + local_x_offset),
+ ((LOGO_Y_OFFSET+LOGO_NAME_HEIGHT+LOGO_WEBSITE_HEIGHT) * nedsim->cell_size + nedsim->origin_y_offset - local_y_offset), "subgeniuskitty.com", 18);
+}
+
+// TODO: Explain
+static void
+draw_halt(struct NEDsim * nedsim)
+{
+#define HALT_X_OFFSET 26
+#define HALT_Y_OFFSET 2
+#define HALT_WIDTH 6
+#define HALT_LIGHT_HEIGHT 6
+#define HALT_LABEL_HEIGHT 2
+
+ // First draw the two colored boxes that comprise the halt area.
+ set_color(nedsim, &color_list[nedsim->color_index].tertiary);
+ draw_rect_area(nedsim, HALT_X_OFFSET, HALT_Y_OFFSET, HALT_WIDTH, HALT_LIGHT_HEIGHT, True, True, False, False);
+ set_color(nedsim, &color_list[nedsim->color_index].secondary);
+ draw_rect_area(nedsim, HALT_X_OFFSET, HALT_Y_OFFSET+HALT_LIGHT_HEIGHT, HALT_WIDTH, HALT_LABEL_HEIGHT, False, True, False, False);
+
+ // And finally, draw the label.
+ set_color(nedsim, &color_list[nedsim->color_index].text);
+ int text_x_size, text_y_size;
+ get_text_size(nedsim, "HALT", &text_x_size, &text_y_size);
+ int local_x_offset = ((HALT_WIDTH * nedsim->cell_size) - text_x_size) / 2;
+ int local_y_offset = ((HALT_LABEL_HEIGHT * nedsim->cell_size) - text_y_size) / 2;
+ XDrawString(nedsim->dpy, nedsim->win, nedsim->gc, (HALT_X_OFFSET * nedsim->cell_size + nedsim->origin_x_offset + local_x_offset),
+ ((HALT_Y_OFFSET+HALT_LIGHT_HEIGHT+HALT_LABEL_HEIGHT) * nedsim->cell_size + nedsim->origin_y_offset - local_y_offset), "HALT", 4);
+}
+
+// TODO: Explain
+static void
+draw_wordline_lights(struct NEDsim * nedsim, uint32_t word, int x, int y)
+{
+#define WORDLINE_BITS_PER_STRIPE 4
+#define WORDLINE_WIDTH 32
+#define WORDLINE_HEIGHT 1
+
+ for (int i = 0; i < WORDLINE_WIDTH; i++) {
+ if (word & (1<<(WORDLINE_WIDTH-1-i))) {
+ set_color(nedsim, &color_list[nedsim->color_index].light_on);
+ } else {
+ set_color(nedsim, &color_list[nedsim->color_index].light_off);
+ }
+ draw_circular_area(nedsim, x+i, y, WORDLINE_HEIGHT);
+ }
+}
+
+// TODO: Explain
+static void
+draw_wordline(struct NEDsim * nedsim, int x, int y)
+{
+ // First, draw a solid box in the primary color over the entire wordline area.
+ set_color(nedsim, &color_list[nedsim->color_index].primary);
+ draw_rect_area(nedsim, x, y, WORDLINE_WIDTH, WORDLINE_HEIGHT, False, True, False, False);
+
+ // Now, draw stripes in the secondary color.
+ int i;
+ for (i = 0; i < (WORDLINE_WIDTH/(2*WORDLINE_BITS_PER_STRIPE)); i++) {
+ set_color(nedsim, &color_list[nedsim->color_index].secondary);
+ draw_rect_area(nedsim, (x+(i*(WORDLINE_WIDTH/WORDLINE_BITS_PER_STRIPE))), y,
+ WORDLINE_BITS_PER_STRIPE, WORDLINE_HEIGHT, False, True, False, False);
+ }
+
+ // Finally, draw the lights.
+ draw_wordline_lights(nedsim, 0, x, y);
+}
+
+// TODO: Explain
+static void
+draw_pc(struct NEDsim * nedsim)
+{
+// TODO: Note that all #defines use units of 'cells', not 'pixels', etc.
+#define PC_X_OFFSET 36
+#define PC_Y_OFFSET 7
+#define PC_WIDTH 32
+#define PC_LABEL_HEIGHT 2
+#define PC_LIGHT_HEIGHT 1
+
+ // First draw the two colored boxes that comprise the PC area.
+ set_color(nedsim, &color_list[nedsim->color_index].tertiary);
+ draw_rect_area(nedsim, PC_X_OFFSET, PC_Y_OFFSET, PC_WIDTH, PC_LABEL_HEIGHT, True, True, False, False);
+ draw_wordline(nedsim, PC_X_OFFSET, PC_Y_OFFSET+PC_LABEL_HEIGHT);
+
+ // Now draw the label text "PC".
+ set_color(nedsim, &color_list[nedsim->color_index].text);
+ int text_x_size, text_y_size;
+ get_text_size(nedsim, "PC", &text_x_size, &text_y_size);
+ int local_x_offset = ((PC_WIDTH * nedsim->cell_size) - text_x_size) / 2;
+ int local_y_offset = ((PC_LABEL_HEIGHT * nedsim->cell_size) - text_y_size) / 2;
+ XDrawString(nedsim->dpy, nedsim->win, nedsim->gc, (PC_X_OFFSET * nedsim->cell_size + nedsim->origin_x_offset + local_x_offset),
+ ((PC_Y_OFFSET+PC_LABEL_HEIGHT) * nedsim->cell_size + nedsim->origin_y_offset - local_y_offset), "PC", 2);
+}
+
+// TODO: Explain
+static void
+draw_sc(struct NEDsim * nedsim)
+{
+#define SC_X_OFFSET 42
+#define SC_Y_OFFSET 2
+#define SC_WIDTH 5
+#define SC_LABEL_HEIGHT 2
+#define SC_LIGHT_HEIGHT 1
+
+ // First draw the two colored boxes that comprise the SC area.
+ set_color(nedsim, &color_list[nedsim->color_index].secondary);
+ draw_rect_area(nedsim, SC_X_OFFSET, SC_Y_OFFSET, SC_WIDTH, SC_LABEL_HEIGHT, True, True, False, False);
+ set_color(nedsim, &color_list[nedsim->color_index].tertiary);
+ draw_rect_area(nedsim, SC_X_OFFSET, SC_Y_OFFSET+SC_LABEL_HEIGHT, SC_WIDTH, SC_LIGHT_HEIGHT, False, True, False, False);
+
+ // Now draw the label text "SC".
+ set_color(nedsim, &color_list[nedsim->color_index].text);
+ int text_x_size, text_y_size;
+ get_text_size(nedsim, "SC", &text_x_size, &text_y_size);
+ int local_x_offset = ((SC_WIDTH * nedsim->cell_size) - text_x_size) / 2;
+ int local_y_offset = ((SC_LABEL_HEIGHT * nedsim->cell_size) - text_y_size) / 2;
+ XDrawString(nedsim->dpy, nedsim->win, nedsim->gc, (SC_X_OFFSET * nedsim->cell_size + nedsim->origin_x_offset + local_x_offset),
+ ((SC_Y_OFFSET+SC_LABEL_HEIGHT) * nedsim->cell_size + nedsim->origin_y_offset - local_y_offset), "SC", 2);
+}
+
+// TODO: Explain
+static void
+draw_psw(struct NEDsim * nedsim)
+{
+#define PSW_N_X_OFFSET 51
+#define PSW_Z_X_OFFSET 58
+#define PSW_Y_OFFSET 2
+#define PSW_LABEL_WIDTH 3
+#define PSW_LABEL_HEIGHT 2
+#define PSW_LIGHT_WIDTH 1
+#define PSW_LIGHT_HEIGHT 1
+
+ // First draw the four colored boxes that comprise the two PSW areas.
+ set_color(nedsim, &color_list[nedsim->color_index].secondary);
+ draw_rect_area(nedsim, PSW_N_X_OFFSET, PSW_Y_OFFSET, PSW_LABEL_WIDTH, PSW_LABEL_HEIGHT, True, True, False, False);
+ set_color(nedsim, &color_list[nedsim->color_index].secondary);
+ draw_rect_area(nedsim, PSW_Z_X_OFFSET, PSW_Y_OFFSET, PSW_LABEL_WIDTH, PSW_LABEL_HEIGHT, True, True, False, False);
+ set_color(nedsim, &color_list[nedsim->color_index].tertiary);
+ draw_rect_area(nedsim, (PSW_N_X_OFFSET + 1), PSW_Y_OFFSET+PSW_LABEL_HEIGHT, PSW_LIGHT_WIDTH, PSW_LIGHT_HEIGHT, False, True, False, False);
+ set_color(nedsim, &color_list[nedsim->color_index].tertiary);
+ draw_rect_area(nedsim, (PSW_Z_X_OFFSET + 1), PSW_Y_OFFSET+PSW_LABEL_HEIGHT, PSW_LIGHT_WIDTH, PSW_LIGHT_HEIGHT, False, True, False, False);
+
+ // Now draw the label text "N".
+ set_color(nedsim, &color_list[nedsim->color_index].text);
+ int text_x_size, text_y_size;
+ get_text_size(nedsim, "N", &text_x_size, &text_y_size);
+ int local_x_offset = ((PSW_LABEL_WIDTH * nedsim->cell_size) - text_x_size) / 2;
+ int local_y_offset = ((PSW_LABEL_HEIGHT * nedsim->cell_size) - text_y_size) / 2;
+ XDrawString(nedsim->dpy, nedsim->win, nedsim->gc, (PSW_N_X_OFFSET * nedsim->cell_size + nedsim->origin_x_offset + local_x_offset),
+ ((PSW_Y_OFFSET+PSW_LABEL_HEIGHT) * nedsim->cell_size + nedsim->origin_y_offset - local_y_offset), "N", 1);
+
+ // Now draw the label text "Z".
+ set_color(nedsim, &color_list[nedsim->color_index].text);
+ get_text_size(nedsim, "Z", &text_x_size, &text_y_size);
+ local_x_offset = ((PSW_LABEL_WIDTH * nedsim->cell_size) - text_x_size) / 2;
+ local_y_offset = ((PSW_LABEL_HEIGHT * nedsim->cell_size) - text_y_size) / 2;
+ XDrawString(nedsim->dpy, nedsim->win, nedsim->gc, (PSW_Z_X_OFFSET * nedsim->cell_size + nedsim->origin_x_offset + local_x_offset),
+ ((PSW_Y_OFFSET+PSW_LABEL_HEIGHT) * nedsim->cell_size + nedsim->origin_y_offset - local_y_offset), "Z", 1);
+}
+
+// TODO: Explain
+static void
+draw_stack(struct NEDsim * nedsim)
+{
+#define STACK_X_OFFSET 2
+#define STACK_Y_OFFSET 12
+#define STACK_WIDTH 32
+#define STACK_LABEL_HEIGHT 2
+#define STACK_LIGHT_HEIGHT 1
+
+ // First draw the two colored boxes that comprise the stack area.
+ set_color(nedsim, &color_list[nedsim->color_index].tertiary);
+ draw_rect_area(nedsim, STACK_X_OFFSET, STACK_Y_OFFSET, STACK_WIDTH, STACK_LABEL_HEIGHT, True, True, False, False);
+ for (int i = 0; i < nedsim->num_data_rows; i++) {
+ draw_wordline(nedsim, STACK_X_OFFSET, STACK_Y_OFFSET+STACK_LABEL_HEIGHT+i);
+ }
+
+ // Now draw the label text "Stack Size:".
+ set_color(nedsim, &color_list[nedsim->color_index].text);
+ int text_x_size, text_y_size;
+ get_text_size(nedsim, "Stack Size:", &text_x_size, &text_y_size);
+ int local_y_offset = ((STACK_LABEL_HEIGHT * nedsim->cell_size) - text_y_size) / 2;
+ XDrawString(nedsim->dpy, nedsim->win, nedsim->gc, ((STACK_X_OFFSET + 1) * nedsim->cell_size + nedsim->origin_x_offset),
+ ((STACK_Y_OFFSET+STACK_LABEL_HEIGHT) * nedsim->cell_size + nedsim->origin_y_offset - local_y_offset), "Stack Size:", 11);
+}
+
+// TODO: Explain
+static void
+draw_heap(struct NEDsim * nedsim)
+{
+#define HEAP_X_OFFSET 36
+#define HEAP_Y_OFFSET 12
+#define HEAP_WIDTH 32
+#define HEAP_LABEL_HEIGHT 2
+#define HEAP_LIGHT_HEIGHT 1
+// TODO: What should I do about this define? I would like to be able to specify the address so I can do things like display the code itself if nothign interesting happens in RAM.
+#define HEAP_START_ADDRESS 0x20000000
+
+ // First draw the two colored boxes that comprise the heap area.
+ set_color(nedsim, &color_list[nedsim->color_index].tertiary);
+ draw_rect_area(nedsim, HEAP_X_OFFSET, HEAP_Y_OFFSET, HEAP_WIDTH, HEAP_LABEL_HEIGHT, True, True, False, False);
+ for (int i = 0; i < nedsim->num_data_rows; i++) {
+ draw_wordline(nedsim, HEAP_X_OFFSET, HEAP_Y_OFFSET+HEAP_LABEL_HEIGHT+i);
+ }
+
+ // Now draw the label text "RAM Base:".
+ set_color(nedsim, &color_list[nedsim->color_index].text);
+ int text_x_size, text_y_size;
+ get_text_size(nedsim, "RAM Base:", &text_x_size, &text_y_size);
+ int local_y_offset = ((HEAP_LABEL_HEIGHT * nedsim->cell_size) - text_y_size) / 2;
+ XDrawString(nedsim->dpy, nedsim->win, nedsim->gc, ((HEAP_X_OFFSET + 1) * nedsim->cell_size + nedsim->origin_x_offset),
+ ((HEAP_Y_OFFSET+HEAP_LABEL_HEIGHT) * nedsim->cell_size + nedsim->origin_y_offset - local_y_offset), "RAM Base:", 9);
+
+ // Now draw the address text.
+ set_color(nedsim, &color_list[nedsim->color_index].text);
+ char address[11];
+ snprintf(address, sizeof(address), "0x%08X", HEAP_START_ADDRESS);
+ get_text_size(nedsim, address, &text_x_size, &text_y_size);
+ local_y_offset = ((HEAP_LABEL_HEIGHT * nedsim->cell_size) - text_y_size) / 2;
+ XDrawString(nedsim->dpy, nedsim->win, nedsim->gc, ((HEAP_X_OFFSET + 1 + (HEAP_WIDTH / 2)) * nedsim->cell_size + nedsim->origin_x_offset),
+ ((HEAP_Y_OFFSET+HEAP_LABEL_HEIGHT) * nedsim->cell_size + nedsim->origin_y_offset - local_y_offset), address, strlen(address));
+}
+
+// TODO: Explain
+static void
+update_display(struct NEDsim * nedsim)
+{
+ // Draw the halt indicator.
+ if (nedsim->nedstate->halted) {
+ set_color(nedsim, &color_list[nedsim->color_index].error_on);
+ } else {
+ set_color(nedsim, &color_list[nedsim->color_index].error_off);
+ }
+ draw_circular_area(nedsim, HALT_X_OFFSET, HALT_Y_OFFSET, HALT_WIDTH);
+
+ // Draw the PSW "N" light.
+ if (nedsim->nedstate->active_thread->psw->negative) {
+ set_color(nedsim, &color_list[nedsim->color_index].light_on);
+ } else {
+ set_color(nedsim, &color_list[nedsim->color_index].light_off);
+ }
+ draw_circular_area(nedsim, PSW_N_X_OFFSET+1, PSW_Y_OFFSET+PSW_LABEL_HEIGHT, PSW_LIGHT_HEIGHT);
+
+ // Draw the PSW "Z" light.
+ if (nedsim->nedstate->active_thread->psw->zero) {
+ set_color(nedsim, &color_list[nedsim->color_index].light_on);
+ } else {
+ set_color(nedsim, &color_list[nedsim->color_index].light_off);
+ }
+ draw_circular_area(nedsim, PSW_Z_X_OFFSET+1, PSW_Y_OFFSET+PSW_LABEL_HEIGHT, PSW_LIGHT_HEIGHT);
+
+
+ // Draw the SC.
+ int i;
+ for (i = 0; i < SC_WIDTH; i++) {
+ if ((SC_WIDTH-1-i) == nedsim->nedstate->active_thread->sc) {
+ set_color(nedsim, &color_list[nedsim->color_index].light_on);
+ } else {
+ set_color(nedsim, &color_list[nedsim->color_index].light_off);
+ }
+ draw_circular_area(nedsim, SC_X_OFFSET+i, SC_Y_OFFSET+SC_LABEL_HEIGHT, SC_LIGHT_HEIGHT);
+ }
+
+ // Draw the PC.
+ draw_wordline_lights(nedsim, nedsim->nedstate->active_thread->pc, PC_X_OFFSET, PC_Y_OFFSET+PC_LABEL_HEIGHT);
+
+ // Draw the stack lights.
+ int64_t top_of_stack = ((int64_t)nedsim->nedstate->active_thread->sp) - 1;
+ for (i = 0; i < nedsim->num_data_rows; i++) {
+ if ((top_of_stack-i) >= 0) {
+ draw_wordline_lights(nedsim, nedsim->nedstate->active_thread->stack[top_of_stack-i], STACK_X_OFFSET, STACK_Y_OFFSET+STACK_LABEL_HEIGHT+i);
+ } else {
+ draw_wordline_lights(nedsim, 0, STACK_X_OFFSET, STACK_Y_OFFSET+STACK_LABEL_HEIGHT+i);
+ }
+ }
+
+ // Draw the stack size in text.
+ set_color(nedsim, &color_list[nedsim->color_index].tertiary);
+ draw_rect_area(nedsim, STACK_X_OFFSET+(STACK_WIDTH/2), STACK_Y_OFFSET, STACK_WIDTH/2, STACK_LABEL_HEIGHT, True, True, False, False);
+ set_color(nedsim, &color_list[nedsim->color_index].text);
+ char stack_size[11];
+ snprintf(stack_size, sizeof(stack_size), "0x%08X", nedsim->nedstate->active_thread->sp);
+ int text_x_size, text_y_size;
+ get_text_size(nedsim, stack_size, &text_x_size, &text_y_size);
+ int local_y_offset = ((STACK_LABEL_HEIGHT * nedsim->cell_size) - text_y_size) / 2;
+ XDrawString(nedsim->dpy, nedsim->win, nedsim->gc, ((STACK_X_OFFSET + 1 + (STACK_WIDTH / 2)) * nedsim->cell_size + nedsim->origin_x_offset),
+ ((STACK_Y_OFFSET+STACK_LABEL_HEIGHT) * nedsim->cell_size + nedsim->origin_y_offset - local_y_offset), stack_size, strlen(stack_size));
+
+ // Draw the heap lights.
+ for (i = 0; i < nedsim->num_data_rows; i++) {
+ draw_wordline_lights(nedsim, ram_r_word(nedsim->nedstate, HEAP_START_ADDRESS+(i*BPW)), HEAP_X_OFFSET, HEAP_Y_OFFSET+HEAP_LABEL_HEIGHT+i);
+ }
+}
+
+/* -------------------------------------------------------------------------- */
+/* Screenhack API Functions */
+/* -------------------------------------------------------------------------- */
+
+static Bool
+NEDsim_event(Display * dpy, Window win, void * closure, XEvent * event)
+{
+ return False;
+}
+
+static void
+NEDsim_free(Display * dpy, Window win, void * closure)
+{
+ // TODO: Replace all this with proper code to free everything.
+ struct NEDsim * nedsim = closure;
+ XFreeGC(nedsim->dpy, nedsim->gc);
+ free(nedsim);
+}
+
+static void *
+NEDsim_init(Display * dpy, Window win)
+{
+ struct NEDsim * nedsim;
+ XGCValues gcv;
+ XWindowAttributes xgwa;
+
+ nedsim = calloc(1, sizeof(*nedsim));
+ if (!nedsim) {
+ fprintf(stderr, "ERROR: Failed to calloc() for NEDsim struct in NEDsim_init().\n");
+ exit(EXIT_FAILURE);
+ }
+
+ nedsim->dpy = dpy;
+ nedsim->win = win;
+
+ XGetWindowAttributes(nedsim->dpy, nedsim->win, &xgwa);
+ nedsim->dpy_width = xgwa.width;
+ nedsim->dpy_height = xgwa.height;
+
+ // TODO: Explain that this is the delay between each clock cycle of the simulated NED CPU.
+ nedsim->delay = get_integer_resource(nedsim->dpy, "delay", "Integer");
+ nedsim->delay *= 1000; /* Turn milliseconds into microseconds. */
+
+ // TODO: Read in the a.out file. This should be done in the simulator's init function call?
+ nedsim->nedstate = init_simulator();
+
+ nedsim->gc = XCreateGC(nedsim->dpy, nedsim->win, GCForeground, &gcv);
+
+ // TODO: Do this properly.
+ nedsim->color_index = 0;
+
+// TODO: Save the GIMP reference diagram somewhere, along with notes about the size/spacing, and that each cell is 10 pixels across in the reference image.
+
+ nedsim->cell_size = nedsim->dpy_width / OVERALL_WIDTH_IN_CELLS ; // make panel as wide as it can be while keeping every cell an integer pixel size.
+ // TODO: What is my minimum cell_size? Below that, I should simply paint the window red and print an error in the console. Perform that check here, right after setting cell_size.
+ // For now, we'll just make it 10 pixels?
+ if (nedsim->cell_size < 10) {
+ nedsim->suitable_display = False;
+ return nedsim;
+ }
+ nedsim->origin_x_offset = (nedsim->dpy_width - (nedsim->cell_size * OVERALL_WIDTH_IN_CELLS)) / 2; // center panel horizontally
+
+ // Determine how many rows for the stack and heap displays. Make it the largest power of two that fits on the display.
+ int available_space_for_data_rows = nedsim->dpy_height - (nedsim->cell_size * (HEADER_HEIGHT_IN_CELLS + FOOTER_HEIGHT_IN_CELLS));
+ for (int i = 0; ; i++) {
+ if ((nedsim->cell_size * (1 << i)) > available_space_for_data_rows) {
+ nedsim->num_data_rows = (1 << --i);
+ break;
+ }
+ }
+ if (nedsim->num_data_rows < 4) {
+ nedsim->suitable_display = False;
+ return nedsim;
+ }
+ nedsim->origin_y_offset = (nedsim->dpy_height - (nedsim->cell_size * (HEADER_HEIGHT_IN_CELLS + nedsim->num_data_rows + FOOTER_HEIGHT_IN_CELLS))) / 2; // center panel vertically
+
+ // Scale border relative to cell_size in a 1:10 relationship.
+ nedsim->border_size = nedsim->cell_size / 10;
+
+ draw_panel(nedsim);
+ draw_logo(nedsim);
+ draw_halt(nedsim);
+ draw_pc(nedsim);
+ draw_sc(nedsim);
+ draw_psw(nedsim);
+ draw_stack(nedsim);
+ draw_heap(nedsim);
+
+ nedsim->suitable_display = True;
+
+ return nedsim;
+}
+
+static unsigned long
+NEDsim_draw(Display * dpy, Window win, void * closure)
+{
+ struct NEDsim * nedsim = closure;
+
+ if (nedsim->suitable_display) {
+ nedsim->nedstate = run_simulator(nedsim->nedstate);
+ update_display(nedsim);
+ } else {
+ set_color(nedsim, &color_list[nedsim->color_index].error_on);
+ XFillRectangle(nedsim->dpy, nedsim->win, nedsim->gc, 0, 0, nedsim->dpy_width, nedsim->dpy_height);
+ }
+
+ return nedsim->delay;
+}
+
+static void
+NEDsim_reshape(Display * dpy, Window win, void * closure, unsigned int w, unsigned int h)
+{
+ struct NEDsim * nedsim = closure;
+ XWindowAttributes xgwa;
+ XGetWindowAttributes(nedsim->dpy, nedsim->win, &xgwa);
+ /* Only restart the simulation if the window changed size. */
+ if (nedsim->dpy_width != xgwa.width || nedsim->dpy_height != xgwa.height) {
+ NEDsim_free(dpy, win, closure);
+ closure = NEDsim_init(dpy, win);
+ }
+}
+
+static const char * NEDsim_defaults[] = {
+ "*delay: 250",
+ 0
+};
+
+static XrmOptionDescRec NEDsim_options[] = {
+ { "-delay", ".delay", XrmoptionSepArg, 0 },
+ { 0, 0, 0, 0 }
+};
+
+XSCREENSAVER_MODULE ("Blinken-lights simulator for NED1 CPU architecture.", NEDsim)
--- /dev/null
+/*
+ * © 2018 Aaron Taylor <ataylor at subgeniuskitty dot com>
+ * See LICENSE.txt file for copyright and license details.
+ *
+ * Some parts of this file were imported from other projects.
+ * See `ned/misc/licenses/` and git history for details.
+ */
+
+#include <stdint.h>
+
+#ifndef NED_A_OUT_H
+#define NED_A_OUT_H
+
+/*
+ * A binary file consists of up to 7 sections. In order, these sections are:
+ *
+ * exec header
+ *
+ * Contains parameters used by the kernel to load a binary file into
+ * memory and execute it, and by the link editor to combine a binary
+ * file with other binary files. This section is the only mandatory
+ * one.
+ *
+ * text segment
+ *
+ * Contains machine code and related data that are loaded into memory
+ * when a program executes. May be loaded read-only.
+ *
+ * data segment
+ *
+ * Contains initialized data; always loaded into writable memory.
+ *
+ * text relocations
+ *
+ * Contains records used by the link editor to update pointers in the
+ * text segment when combining binary files.
+ *
+ * data relocations
+ *
+ * Like the text relocation section, but for data segment pointers.
+ *
+ * symbol table
+ *
+ * Contains records used by the link editor to cross reference the
+ * addresses of named variables and functions (`symbols') between
+ * binary files.
+ *
+ * string table
+ *
+ * Contains the character strings corresponding to the symbol names.
+ *
+ * Every binary file begins with an exec structure:
+ */
+
+struct exec {
+ uint32_t a_midmag; /* flags<<26 | mid<<16 | magic */
+ uint32_t a_text; /* text segment size */
+ uint32_t a_data; /* initialized data size */
+ uint32_t a_bss; /* uninitialized data size */
+ uint32_t a_syms; /* symbol table size */
+ uint32_t a_entry; /* entry point */
+ uint32_t a_trsize; /* text relocation size */
+ uint32_t a_drsize; /* data relocation size */
+};
+
+/*
+ * The exec fields have the following functions:
+ *
+ * a_midmag
+ *
+ * This field is stored in host byte-order. It has a number of
+ * sub-components accessed by the macros N_GETFLAG(), N_GETMID(), and
+ * N_GETMAGIC(), and set by the macro N_SETMAGIC().
+ *
+ * The macro N_GETFLAG() returns a few flags:
+ *
+ * EX_DYNAMIC
+ *
+ * indicates that the executable requires the services of the
+ * run-time link editor.
+ *
+ * EX_PIC
+ *
+ * indicates that the object contains position independent code.
+ *
+ * If both EX_DYNAMIC and EX_PIC are set, the object file is a position
+ * independent executable image (e.g. a shared library), which is to be
+ * loaded into the process address space by the run-time link editor.
+ *
+ * The macro N_GETMID() returns the machine-id. This indicates which
+ * machine(s) the binary is intended to run on.
+ *
+ * N_GETMAGIC() specifies the magic number, which uniquely identifies
+ * binary files and distinguishes different loading conventions. The field
+ * must contain one of the following values:
+ *
+ * NED_MAGIC1
+ *
+ * The text and data segments immediately follow the header and
+ * are contiguous. Both text and data segments are loaded into
+ * writable memory.
+ *
+ * a_text
+ *
+ * Contains the size of the text segment in bytes.
+ *
+ * a_data
+ *
+ * Contains the size of the data segment in bytes.
+ *
+ * a_bss
+ *
+ * Contains the size of the bss segment in bytes.
+ *
+ * a_syms
+ *
+ * Contains the size of the symbol table segment in bytes.
+ *
+ * a_entry
+ *
+ * Contains the address in memory of the entry point of the program.
+ *
+ * a_trsize
+ *
+ * Contains the size in bytes of the text relocation table.
+ *
+ * a_drsize
+ *
+ * Contains the size in bytes of the data relocation table.
+ *
+ * The <a.out.h> include file defines several macros which use an exec
+ * structure to test consistency or to locate section offsets in the binary
+ * file.
+ *
+ * N_BADMAG(exec)
+ *
+ * Nonzero if the a_magic field does not contain a recognized value.
+ *
+ * N_TXTOFF(exec)
+ *
+ * The byte offset in the binary file of the beginning of the text
+ * segment.
+ *
+ * N_SYMOFF(exec)
+ *
+ * The byte offset of the beginning of the symbol table.
+ *
+ * N_STROFF(exec)
+ *
+ * The byte offset of the beginning of the string table.
+ */
+
+#define N_GETMAGIC(ex) ((ex).a_midmag & 0xffff)
+#define N_GETMID(ex) (((ex).a_midmag >> 16) & 0x03ff)
+#define N_GETFLAG(ex) (((ex).a_midmag >> 26) & 0x3f)
+#define N_SETMAGIC(ex,mag,mid,flag) \
+ ((ex).a_midmag = (((flag) & 0x3f) <<26) | (((mid) & 0x03ff) << 16) | ((mag) & 0xffff))
+
+#define N_BADMAG(ex) (N_GETMAGIC(ex) != NED_MAGIC1)
+
+#define N_TXTOFF(ex) (sizeof(struct exec))
+#define N_DATOFF(ex) (N_TXTOFF(ex) + (ex).a_text)
+#define N_RELOFF(ex) (N_DATOFF(ex) + (ex).a_data)
+#define N_SYMOFF(ex) (N_RELOFF(ex) + (ex).a_trsize + (ex).a_drsize)
+#define N_STROFF(ex) (N_SYMOFF(ex) + (ex).a_syms)
+
+/* There doesn't appear to be any pattern to magic number assignments. */
+/* See: /usr/src/contrib/file/magic/Magdir/aout */
+#define NED_MAGIC1 0x107
+
+/* There doesn't seem to be any pattern to Machine ID number assignments. */
+/* For now, I'm using the sum of the ASCII values for "NED". */
+#define MID_NED 0xD7 /* NED binary */
+
+#define EX_PIC 0x10 /* contains position independent code */
+#define EX_DYNAMIC 0x20 /* contains run-time link-edit info */
+#define EX_DPMASK 0x30 /* mask for the above */
+
+/*
+ * Relocation records have a standard format which is described by the
+ * relocation_info structure:
+ */
+
+struct relocation_info {
+ uint32_t r_address; /* offset in text or data segment */
+ uint32_t r_symbolnum : 24, /* ordinal number of add symbol */
+ r_pcrel : 1, /* 1 if value should be pc-relative */
+ r_length : 2, /* log base 2 of value's width */
+ r_extern : 1, /* 1 if need to add symbol to value */
+ r_baserel : 1, /* linkage table relative */
+ r_jmptable : 1, /* relocate to jump table */
+ r_relative : 1, /* load address relative */
+ r_copy : 1; /* run time copy */
+};
+
+/*
+ * The relocation_info fields are used as follows:
+ *
+ * r_address
+ *
+ * Contains the byte offset of a pointer that needs to be link-edited.
+ * Text relocation offsets are reckoned from the start of the text
+ * segment, and data relocation offsets from the start of the data
+ * segment. The link editor adds the value that is already stored at this
+ * offset into the new value that it computes using this relocation
+ * record.
+ *
+ * r_symbolnum
+ *
+ * Contains the ordinal number of a symbol structure in the symbol table
+ * (it is not a byte offset). After the link editor resolves the absolute
+ * address for this symbol, it adds that address to the pointer that is
+ * under going relocation. (If the r_extern bit is clear, the situation is
+ * different; see below.)
+ *
+ * r_pcrel
+ *
+ * If this is set, the link editor assumes that it is updating a pointer
+ * that is part of a machine code instruction using pc-relative
+ * addressing. The address of the relocated pointer is implicitly added to
+ * its value when the running program uses it.
+ *
+ * r_length
+ *
+ * Contains the log base2 of the length of the pointer in bytes; 0 for
+ * 1-byte displacements, 1 for 2-byte displacements, 2 for 4-byte
+ * displacements.
+ *
+ * r_extern
+ *
+ * Set if this relocation requires an external reference; the link editor
+ * must use a symbol address to update the pointer. When the r_extern bit
+ * is clear, the relocation is `local'; the link editor updates the
+ * pointer to reflect changes in the load addresses of the various
+ * segments, rather than changes in the value of a symbol (except when
+ * r_baserel is also set (see below). In this case, the content of the
+ * r_symbolnum field is an n_type value (see below); this type field tells
+ * the link editor what segment the relocated pointer points into.
+ *
+ * r_baserel
+ *
+ * If set, the symbol, as identified by the r_symbolnum field, is to be
+ * relocated to an offset into the Global Offset Table. At runtime, the
+ * entry in the Global Offset Table at this offset is set to be the
+ * address of the symbol.
+ *
+ * r_jmptable
+ *
+ * If set, the symbol, as identified by the r_symbolnum field, is to be
+ * relocated to an offset into the Procedure Linkage Table.
+ *
+ * r_relative
+ *
+ * If set, this relocation is relative to the (run-time) load address of
+ * the image this object file is going to be a part of. This type of
+ * relocation only occurs in shared objects.
+ *
+ * r_copy
+ *
+ * If set, this relocation record identifies a symbol whose contents
+ * should be copied to the location given in r_address. The copying is
+ * done by the runtime link-editor from a suitable data item in a shared
+ * object.
+ *
+ * Symbols map names to addresses (or more generally, strings to values).
+ * Since the link-editor adjusts addresses, a symbol's name must be used to
+ * stand for its address until an absolute value has been assigned. Symbols
+ * consist of a fixed-length record in the symbol table and a variable-length
+ * name in the string table. The symbol table is an array of nlist structures:
+ */
+
+struct nlist {
+ union {
+ char * n_name;
+ uint32_t n_strx;
+ } n_un;
+ uint32_t n_type;
+ uint32_t n_other;
+ uint32_t n_desc;
+ uint32_t n_value;
+};
+
+/*
+ * The fields are used as follows:
+ *
+ * n_un.n_strx
+ *
+ * Contains a byte offset into the string table for the name of this
+ * symbol.
+ *
+ * n_un.n_name
+ *
+ * Used by the runtime link editor. Contains a pointer to the string in
+ * memory.
+ *
+ * n_type
+ *
+ * Used by the link editor to determine how to update the symbol's value.
+ * The n_type field is broken down into three sub-fields using bitmasks.
+ * The link editor treats symbols with the N_EXT type bit set as
+ * `external' symbols and permits references to them from other binary
+ * files. The N_TYPE mask selects bits of interest to the link editor:
+ *
+ * N_UNDF
+ *
+ * An undefined symbol. The link editor must locate an external
+ * symbol with the same name in another binary file to determine
+ * the absolute value of this symbol. As a special case, if the
+ * n_value field is nonzero and no binary file in the link-edit
+ * defines this symbol, the link-editor will resolve this symbol
+ * to an address in the bss segment, reserving an amount of bytes
+ * equal to n_value. If this symbol is undefined in more than one
+ * binary file and the binary files do not agree on the size, the
+ * link editor chooses the greatest size found across all
+ * binaries.
+ *
+ * N_ABS
+ *
+ * An absolute symbol. The link editor does not update an absolute
+ * symbol.
+ *
+ * N_TEXT
+ *
+ * A text symbol. This symbol's value is a text address and the
+ * link editor will update it when it merges binary files.
+ *
+ * N_DATA
+ *
+ * A data symbol; similar to N_TEXT but for data addresses. The
+ * values for text and data symbols are not file offsets but
+ * addresses; to recover the file offsets, it is necessary to
+ * identify the loaded address of the beginning of the
+ * corresponding section and subtract it, then add the offset of
+ * the section.
+ *
+ * N_BSS
+ *
+ * A bss symbol; like text or data symbols but has no
+ * corresponding offset in the binary file.
+ *
+ * The N_STAB mask selects bits of interest to symbolic debuggers.
+ *
+ * n_other
+ *
+ * This field provides information on the nature of the symbol independent
+ * of the symbol's location in terms of segments as determined by the
+ * n_type field. Currently, the lower 4 bits of the n_other field hold one
+ * of two values: AUX_FUNC and AUX_OBJECT. AUX_FUNC associates the symbol
+ * with a callable function, while AUX_OBJECT associates the symbol with
+ * data, irrespective of their locations in either the text or the data
+ * segment.
+ *
+ * n_desc
+ *
+ * Reserved for use by debuggers; passed untouched by the link editor.
+ * Different debuggers use this field for different purposes.
+ *
+ * n_value
+ *
+ * Contains the value of the symbol. For text, data and bss symbols, this
+ * is an address; for other symbols (such as debugger symbols), the value
+ * may be arbitrary.
+ *
+ * The string table consists of a 32-bit length followed by null-terminated
+ * symbol strings. The length represents the sizeof the entire table in bytes,
+ * so its minimum value (or the offset of the first string) is always 4 on
+ * 32-bit machines.
+ */
+
+/* Used in nlist.n_type. */
+#define N_UNDF 0x00 /* undefined */
+#define N_ABS 0x02 /* absolute address */
+#define N_TEXT 0x04 /* text segment */
+#define N_DATA 0x08 /* data segment */
+#define N_BSS 0x10 /* bss segment */
+
+#define N_EXT 0x01 /* external (global) bit, OR'ed in */
+#define N_TYPE 0xff /* mask for all the type bits */
+#define N_STAB 0xffffff00 /* mask for debugger symbols -- stab(5) */
+
+/* Used in nlist.n_other */
+#define AUX_FUNC 1 /* Function */
+#define AUX_OBJECT 2 /* Data */
+
+#endif
--- /dev/null
+/* (c) 2021 Aaron Taylor <ataylor at subgeniuskitty dot com> */
+/* See LICENSE.txt file for copyright and license details. */
+
+/* -------------------------------------------------------------------------- */
+/* NED1 Simulator */
+/* -------------------------------------------------------------------------- */
+
+// TODO: Make a bunch of functions private in this file.
+#include <stdio.h>
+#include <stdint.h>
+#include <inttypes.h>
+#include <stdlib.h>
+#include <stdbool.h>
+#include <unistd.h>
+#include <fcntl.h>
+#include <string.h>
+#include <errno.h>
+#include <time.h>
+#include <termios.h>
+#include <signal.h>
+#include <sys/socket.h>
+#include <sys/types.h>
+#include <netinet/in.h>
+#include <arpa/inet.h>
+#include <netdb.h>
+
+#include "a.out.h"
+#include "simulator.h"
+
+int
+is_stdin_nonempty(void)
+{
+ fd_set read_fds;
+ FD_ZERO(&read_fds);
+ FD_SET(STDIN_FILENO, &read_fds);
+
+ struct timeval timeout;
+ timeout.tv_sec = 0;
+ timeout.tv_usec = 0;
+
+ int retval = select(1, &read_fds, NULL, NULL, &timeout);
+
+ if (retval == -1) {
+ /* TODO: How do I want to handle this error? */
+ }
+
+ return retval;
+}
+
+uint32_t
+generate_binary_psw(struct NEDstate * state)
+{
+ uint32_t psw = 0;
+ if (state->active_thread->psw->zero) psw |= 0b1;
+ if (state->active_thread->psw->negative) psw |= 0b10;
+ return psw;
+}
+
+void
+ram_w_byte(struct NEDstate * state, uint32_t address, uint8_t data)
+{
+ state->ram[address] = data;
+}
+
+uint8_t
+ram_r_byte(struct NEDstate * state, uint32_t address)
+{
+ return state->ram[address];
+}
+
+/* For now, with only a terminal for IO, we pick off IO requests when accessing RAM. */
+/* TODO: Improve this before adding any other IO devices like disks. */
+
+void
+ram_w_word(struct NEDstate * state, uint32_t address, uint32_t data)
+{
+ /* TODO: Since PC and PSW are memory mapped, they should accept writes. */
+ /* Should writes to the PC automatically reset the syllable counter? */
+ if (address == 0x8000000) { /* SLU: XBUF */
+ printf("%c", data);
+ fflush(stdout);
+ } else if (address == 0x0 || address == 0x4) {
+ /* Intentionally empty */
+ } else if (address >= 0x20000000) {
+ for (int i=3; i>=0; i--) {
+ uint8_t tmp_byte = ((data >> (8*(3-i))) & 0xff);
+ ram_w_byte(state,address+i,tmp_byte);
+ }
+ }
+}
+
+uint32_t
+ram_r_word(struct NEDstate * state, uint32_t address)
+{
+ if (address == 0x0) { /* Zero register */
+ return 0b0;
+ } else if (address == 0x4) { /* 0x80000000 register */
+ return 0x80000000;
+ } else if (address == 0x8) { /* PC register */
+ return state->active_thread->pc;
+ } else if (address == 0xC) { /* PSW register */
+ return generate_binary_psw(state);
+ } else if (address == 0x8000004) { /* SLU: XCSR */
+ /* TODO: Should I artificially restrict printing in the simulator? */
+ /* It might help catch bugs like the GCC bug that slipped past SIMH. */
+ return 0b1;
+ } else if (address == 0x8000008) { /* SLU: RBUF */
+ if (is_stdin_nonempty()) {
+ return getchar();
+ } else {
+ return (uint8_t)rand();
+ }
+ } else if (address == 0x800000C) { /* SLU: RCSR */
+ if (is_stdin_nonempty()) {
+ return 0b1;
+ } else {
+ return 0b0;
+ }
+ } else if (address >= 0x20000000) { /* RAM */
+ uint32_t word = 0;
+ for (int i=0; i<4; i++) word |= (ram_r_byte(state,address+i)) << (8*(3-i));
+ return word;
+ }
+ return 0b0;
+}
+
+uint32_t
+fetch_instruction_word(struct NEDstate * state)
+{
+ uint32_t word = ram_r_word(state, state->active_thread->pc);
+ state->active_thread->pc += BPW;
+ return word;
+}
+
+void
+stack_w(struct NEDthread * thread, uint32_t value, uint8_t offset)
+{
+ thread->stack[thread->sp - (offset + 1)] = value;
+}
+
+uint32_t
+stack_r(struct NEDthread * thread, uint8_t offset)
+{
+ return thread->stack[thread->sp - (offset + 1)];
+}
+
+void
+stack_push(struct NEDthread * thread, uint32_t value)
+{
+ thread->stack[thread->sp++] = value;
+}
+
+uint32_t
+stack_pop(struct NEDthread * thread)
+{
+ return thread->stack[--thread->sp];
+}
+
+void
+set_psw_flags(uint32_t word, struct NEDstate * state)
+{
+ if (word == 0) {
+ state->active_thread->psw->zero = true;
+ } else {
+ state->active_thread->psw->zero = false;
+ }
+ if (word & 0x80000000) {
+ state->active_thread->psw->negative = true;
+ } else {
+ state->active_thread->psw->negative = false;
+ }
+}
+
+void
+ned_instruction_and(struct NEDstate * state)
+{
+ uint32_t operand1 = stack_pop(state->active_thread);
+ uint32_t operand2 = stack_pop(state->active_thread);
+ stack_push(state->active_thread, (operand1 & operand2));
+ set_psw_flags(stack_r(state->active_thread,0), state);
+}
+
+void
+ned_instruction_or(struct NEDstate * state)
+{
+ uint32_t operand1 = stack_pop(state->active_thread);
+ uint32_t operand2 = stack_pop(state->active_thread);
+ stack_push(state->active_thread, (operand1 | operand2));
+ set_psw_flags(stack_r(state->active_thread,0), state);
+}
+
+void
+ned_instruction_not(struct NEDstate * state)
+{
+ stack_push(state->active_thread, ~stack_pop(state->active_thread));
+ set_psw_flags(stack_r(state->active_thread,0), state);
+}
+
+void
+ned_instruction_xor(struct NEDstate * state)
+{
+ uint32_t operand1 = stack_pop(state->active_thread);
+ uint32_t operand2 = stack_pop(state->active_thread);
+ stack_push(state->active_thread, (operand1 ^ operand2));
+ set_psw_flags(stack_r(state->active_thread,0), state);
+}
+
+void
+ned_instruction_add(struct NEDstate * state)
+{
+ uint32_t operand1 = stack_pop(state->active_thread);
+ uint32_t operand2 = stack_pop(state->active_thread);
+ stack_push(state->active_thread, (operand1 + operand2));
+ set_psw_flags(stack_r(state->active_thread,0), state);
+}
+
+void
+ned_instruction_mvstck(struct NEDstate * state)
+{
+ uint32_t new_id = stack_pop(state->active_thread);
+ if (new_id < THREAD_COUNT) {
+ state->active_thread = state->thread[new_id];
+ } else {
+ printf("ERROR: Attempted MVSTCK to ID higher than THREAD_COUNT.\n");
+ state->halted = true;
+ }
+}
+
+void
+ned_instruction_shift(struct NEDstate * state)
+{
+ /* TODO: Bounds check: Either all inputs are valid OR shift_by < 32. */
+ /* I guess this also depends if I'm shifting-and-dropping, or barrel-shifting. */
+ /* How should I pad for a right shift if I shift-and-drop? Sign extend? */
+ uint32_t shift_by = stack_pop(state->active_thread);
+ uint32_t word = stack_pop(state->active_thread);
+ if (shift_by & 0x80000000) {
+ stack_push(state->active_thread, (word << (shift_by & 0x7fffffff)));
+ } else {
+ stack_push(state->active_thread, (word >> shift_by));
+ }
+ set_psw_flags(stack_r(state->active_thread,0), state);
+}
+
+void
+ned_instruction_test(struct NEDstate * state)
+{
+ uint32_t word = stack_pop(state->active_thread);
+ set_psw_flags(word, state);
+}
+
+void
+ned_instruction_jmp(struct NEDstate * state)
+{
+ state->active_thread->pc = stack_pop(state->active_thread);
+ // The SC is caught and reset by the main loop since the PC changed.
+}
+
+void
+ned_instruction_swap(struct NEDstate * state)
+{
+ uint32_t temp1 = stack_pop(state->active_thread);
+ uint32_t temp2 = stack_pop(state->active_thread);
+ stack_push(state->active_thread, temp1);
+ stack_push(state->active_thread, temp2);
+ set_psw_flags(stack_r(state->active_thread,0), state);
+}
+
+void
+ned_instruction_brz(struct NEDstate * state)
+{
+ uint32_t new_pc = stack_pop(state->active_thread);
+ uint32_t test_word = stack_pop(state->active_thread);
+ if (test_word == 0) {
+ state->active_thread->pc = new_pc;
+ // The SC is caught and reset by the main loop since the PC changed.
+ }
+}
+
+void
+ned_instruction_load(struct NEDstate * state)
+{
+ uint32_t address = stack_pop(state->active_thread);
+ stack_push(state->active_thread, ram_r_word(state, address));
+ set_psw_flags(stack_r(state->active_thread,0), state);
+}
+
+void
+ned_instruction_store(struct NEDstate * state)
+{
+ uint32_t address = stack_pop(state->active_thread);
+ uint32_t data = stack_pop(state->active_thread);
+ ram_w_word(state, address, data);
+}
+
+void
+ned_instruction_halt(struct NEDstate * state)
+{
+ printf("Halting.\n");
+ state->halted = true;
+}
+
+void
+execute_syllable(struct NEDstate * state, enum syllables syllable)
+{
+ if (syllable & 0b100000) { /* Check the first bit of the syllable. 1 means IM_x. */
+ stack_push(state->active_thread, (uint32_t)(syllable & 0b11111));
+ } else if (syllable & 0b10000) { /* 1 in 2nd bit means LDSP+x or STSP+x instruction. */
+ if (syllable & 0b1000) { /* LDSP+x */
+ stack_push(state->active_thread,stack_r(state->active_thread,(syllable & 0b111)));
+ set_psw_flags(stack_r(state->active_thread,0), state);
+ } else { /* STSP+x */
+ stack_w(state->active_thread,stack_pop(state->active_thread),(syllable & 0b111));
+ }
+ } else {
+ switch (syllable) {
+ case AND: ned_instruction_and(state); break;
+ case OR: ned_instruction_or(state); break;
+ case NOT: ned_instruction_not(state); break;
+ case XOR: ned_instruction_xor(state); break;
+ case ADD: ned_instruction_add(state); break;
+ case MVSTCK: ned_instruction_mvstck(state); break;
+ case SHIFT: ned_instruction_shift(state); break;
+ case CMPSWP: /* TODO */ break;
+ case TEST: ned_instruction_test(state); break;
+ case JMP: ned_instruction_jmp(state); break;
+ case SWAP: ned_instruction_swap(state); break;
+ case BRZ: ned_instruction_brz(state); break;
+ case LOAD: ned_instruction_load(state); break;
+ case STORE: ned_instruction_store(state); break;
+ case NOP: /* Intentionally blank */ break;
+ case HALT: ned_instruction_halt(state); break;
+ default:
+ printf("ERROR: Attempted to execute illegal syllable: 0o%o\n", syllable);
+ state->halted = true;
+ break;
+ }
+ }
+}
+
+uint8_t
+extract_syllable_from_word(uint32_t word, uint8_t index)
+{
+ uint32_t mask = 0b111111 << 6*(4-index);
+ return (word & mask) >> 6*(4-index);
+}
+
+void
+parse_aout_file(FILE * input, struct exec * aout_exec, uint8_t * text_segment,
+ struct nlist ** symbol_table, uint32_t * symbol_count)
+{
+ uint32_t read_count = 0;
+
+ /* Read in and check the a.out header. */
+ for (uint32_t i=0; i<8; i++) {
+ switch (i) {
+ case 0: read_count = fread(&(aout_exec->a_midmag), 4, 1, input); break;
+ case 1: read_count = fread(&(aout_exec->a_text), 4, 1, input); break;
+ case 2: read_count = fread(&(aout_exec->a_data), 4, 1, input); break;
+ case 3: read_count = fread(&(aout_exec->a_bss), 4, 1, input); break;
+ case 4: read_count = fread(&(aout_exec->a_syms), 4, 1, input); break;
+ case 5: read_count = fread(&(aout_exec->a_entry), 4, 1, input); break;
+ case 6: read_count = fread(&(aout_exec->a_trsize), 4, 1, input); break;
+ case 7: read_count = fread(&(aout_exec->a_drsize), 4, 1, input); break;
+ }
+ if (read_count != 1) {
+ fprintf(stderr, "ERROR: Invalid a.out header.\n");
+ exit(EXIT_FAILURE);
+ }
+ }
+ if (N_BADMAG(*aout_exec)) {
+ fprintf(stderr, "ERROR: Invalid magic number in a.out header.\n");
+ exit(EXIT_FAILURE);
+ } else if (N_GETMID(*aout_exec) != MID_NED) {
+ fprintf(stderr, "ERROR: Executable not intended for NED Machine ID.\n");
+ exit(EXIT_FAILURE);
+ }
+
+ /* Read in the text segment. */
+ uint32_t text_segment_size = (N_DATOFF(*aout_exec) - N_TXTOFF(*aout_exec));
+ read_count = fread(text_segment, 1, text_segment_size, input);
+ if (read_count != text_segment_size) {
+ fprintf(stderr, "ERROR: Failed to read entire text segment.\n");
+ exit(EXIT_FAILURE);
+ }
+
+ /* Correct the byte order. */
+ for (uint32_t i=0; i < (text_segment_size / 4); i++) {
+ uint8_t temp_word[4];
+ for (uint8_t j=0; j<4; j++) temp_word[j] = text_segment[((i*4)+j)];
+ for (uint8_t j=0; j<4; j++) text_segment[((i*4)+j)] = temp_word[(3-j)];
+ }
+
+ /* Read in the symbol table. */
+ *symbol_count = ((N_STROFF(*aout_exec) - N_SYMOFF(*aout_exec)) / 20); /* 20 bytes per symbol. */
+ *symbol_table = malloc((*symbol_count) * sizeof(struct nlist));
+ for (uint32_t i=0; i < *symbol_count; i++) {
+ for (uint32_t j=0; j<5; j++) {
+ switch (j) {
+ case 0: read_count = fread(&((*symbol_table)[i].n_un.n_strx), 4, 1, input); break;
+ case 1: read_count = fread(&((*symbol_table)[i].n_type), 4, 1, input); break;
+ case 2: read_count = fread(&((*symbol_table)[i].n_other), 4, 1, input); break;
+ case 3: read_count = fread(&((*symbol_table)[i].n_desc), 4, 1, input); break;
+ case 4: read_count = fread(&((*symbol_table)[i].n_value), 4, 1, input); break;
+ }
+ if (read_count != 1) {
+ fprintf(stderr, "ERROR: Unable to read entire symbol table.\n");
+ exit(EXIT_FAILURE);
+ }
+ }
+ }
+
+ /* Read in the string table and update the symbol table entries with pointers to new strings. */
+ uint32_t string_table_size;
+ read_count = fread(&string_table_size, 4, 1, input);
+ if (read_count != 1) {
+ fprintf(stderr, "ERROR: Failed to read string table size.\n");
+ exit(EXIT_FAILURE);
+ }
+ for (uint32_t i=0; i < *symbol_count; i++) {
+ uint32_t len = 0;
+ if (i < ((*symbol_count)-1)) {
+ len = ((*symbol_table)[i+1].n_un.n_strx - (*symbol_table)[i].n_un.n_strx);
+ } else {
+ len = (string_table_size - (*symbol_table)[i].n_un.n_strx);
+ }
+ (*symbol_table)[i].n_un.n_name = malloc(len);
+ read_count = fread((*symbol_table)[i].n_un.n_name, 1, len, input);
+ if (read_count != len) {
+ fprintf(stderr, "ERROR: Failed to read a string from the string table.\n");
+ exit(EXIT_FAILURE);
+ }
+ }
+
+}
+
+struct NEDstate *
+init_simulator(void)
+{
+ struct NEDstate * state = malloc(sizeof(struct NEDstate));
+ state->hack = malloc(sizeof(struct NEDhack));
+ for (size_t i=0; i < THREAD_COUNT; i++) {
+ state->thread[i] = malloc(sizeof(struct NEDthread));
+ state->thread[i]->psw = malloc(sizeof(struct NEDpsw));
+ }
+ state->thread[0]->pc = 0;
+ state->thread[0]->sc = 0;
+ state->thread[0]->sp = 0;
+ state->thread[0]->psw->zero = false;
+ state->thread[0]->psw->negative = false;
+ state->thread[0]->pc = 0x20000000; /* Data region starts 512 MB into address space. */
+ state->active_thread = state->thread[0]; /* By convention, use thread 0 for init. */
+ state->halted = false;
+ state->hack->resume_word = false;
+
+// TODO: This needs to be passed in as a CLI option.
+#define AOUT_PATH "./test.out"
+
+ /* Load an initial image into memory. */
+ uint32_t address = 0x20000000;
+ struct exec aout_exec;
+ struct nlist * symbol_table;
+ uint32_t symbol_count;
+ FILE * input = NULL;
+ if ((input = fopen(AOUT_PATH, "r")) == NULL) {
+ fprintf(stderr, "ERROR: %s: %s\n", AOUT_PATH, strerror(errno));
+ state->halted = true;
+ }
+ parse_aout_file(input, &aout_exec, &(state->ram[address]), &symbol_table, &symbol_count);
+ fclose(input);
+
+ return state;
+}
+
+struct NEDstate *
+run_simulator(struct NEDstate * state)
+{
+ if (state->halted) return state;
+
+ /* Fetch instruction word. */
+ uint32_t iw;
+ if (state->hack->resume_word) {
+ iw = state->hack->iw;
+ } else {
+ iw = fetch_instruction_word(state);
+ }
+
+ /* Decode instruction word format and execute. */
+ if (iw & (0b1 << 31)) { /* Instruction word is type A. */
+ stack_push(state->active_thread, (iw << 1));
+ } else if ((iw & (0b11 << 30)) == 0) { /* Instruction word is type C. */
+ uint8_t syllable = extract_syllable_from_word(iw, state->active_thread->sc);
+ state->active_thread->sc++; // TODO: Should this be part of extract_syllable_from_word()? After all, incrementing the PC is done in fetch_instruction_word().
+ uint32_t pre_execution_pc = state->active_thread->pc; // TODO: This is so we can catch JMP/JSR/etc subroutines that need the SC to be reset to zero.
+ execute_syllable(state, syllable);
+ if (state->active_thread->pc != pre_execution_pc) {
+ // Jumped to a new address, so prepare to execute a new instruction word.
+ state->active_thread->sc = 0;
+ state->hack->resume_word = false;
+ } else if (state->active_thread->sc >= SPW) {
+ // Just executed the last syllable in this word, time to follow the PC to the next word.
+ state->active_thread->sc = 0;
+ state->hack->resume_word = false;
+ } else {
+ // More syllables remain to be executed in this instruction word.
+ state->hack->resume_word = true;
+ state->hack->iw = iw;
+ }
+ } else {
+ state->halted = true;
+ fprintf(stderr, "WARNING: Halting due to attempted execution of illegal instruction.\n");
+ }
+
+ return state;
+}