pdp11/pdp11_slu.c

// (c) 2020 Aaron Taylor <ataylor at subgeniuskitty dot com>
// See License.txt file for copyright and license details.

#include <stdarg.h>
#include <stdint.h>
#include "pdp11.h"

/*
 * Polled console I/O
 */

void
putch(uint16_t c)
{
    while(!(GET(CONSXCSR,SLUXCSR_XMTRDY))) continue;
    CONSXBUF = c;
}

uint16_t
getch(void)
{
    while(!(GET(CONSRCSR,SLURCSR_RCVRDY))) continue;
    return CONSRBUF;
}


/*
 * Helper functions for use with console IO
 */

void
print_string(const char * string)
{
    while (*string != '\0') {
        putch(*string);
        string++;
    }
}

char
digit_to_ascii(uint16_t digit)
{
    if (digit > 15) {
        print_string("ERROR: Out of range in digit_to_ascii()\r\n");
        // TODO: How do I want to handle runtime errors?
        return 0;
    } else if (digit > 9) {
        digit -= 10;
        digit += 'a';
        return digit;
    } else {
        digit += '0';
        return digit;
    }
}

void
print_uint16_in_octal(uint16_t number)
{
    char output[7]; // +6 for digits; +1 for null-term
    for (int i = 5; i >= 0; i--) {
        output[i] = digit_to_ascii(number % 8);
        number = number / 8;
    }
    output[6] = '\0';
    putch('0');
    print_string(output);
}

void
printf(const char * format, ...)
{
    va_list ap;
    va_start(ap, format);
    while (*format) {
        switch (*format) {
            case '%':
                format++;
                switch (*format) {
                    case 's':
                        {
                        char * s = va_arg(ap, char *);
                        print_string(s);
                        break;
                        }
                    case 'o':
                        {
                        uint16_t u = va_arg(ap, unsigned int);
                        print_uint16_in_octal(u);
                        break;
                        }
                    default:
                        /* Put it back and look innocent. */
                        putch('%');
                        putch(*format);
                        break;
                }
                break;
            case '\\':
                format++;
                switch (*format) {
                    case 'n':
                        print_string("\r\n");
                        break;
                    case 't':
                        putch('\t');
                        break;
                    case '%':
                        putch('%');
                        break;
                    case '\\':
                        putch('\\');
                        break;
                    default:
                        /* Maybe this escape wasn't meant for us. */
                        putch('\\');
                        putch(*format);
                        break;
                }
                break;
            case '\n':
                print_string("\r\n");
                break;
            default:
                putch(*format);
                break;
        }
        format++;
    }
    va_end(ap);
}