[vvhitespace] / vv_interpreter.c

/*
 * (c) 2019 Aaron Taylor <ataylor at subgeniuskitty dot com>
 * All rights reserved.
 */

#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <string.h>
#include <errno.h>
#include <stdint.h>
#include <sys/select.h>
#include <getopt.h>

#define VERSION 1

#define STACKSIZE 1024
#define HEAPSIZE  1024
#define RETURNSTACKSIZE 1024

void
print_usage(char ** argv)
{
    printf( "VVhitespace Interpreter v%d (www.subgeniuskitty.com)\n"
            "Usage: %s -i <file>\n"
            "  -h         Help (prints this message)\n"
            "  -i <file>  Specify a VVhitespace source file to interpret.\n"
            , VERSION, argv[0]
    );
}

int
stdin_empty(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);
    /* retval could be -1. Ignoring that for now. */
    if (retval > 0) return 0;
    return 1;
}

void
ws_die(size_t * pc, char * msg)
{
    printf("\n");
    printf("SIM_ERROR @ PC %lu: %s\n", *pc, msg);
    fflush(stdout);
    exit(EXIT_FAILURE);
}

void
stack_push(int32_t ** sp, int32_t word)
{
    *((*sp)++) = word;
}

int32_t
stack_pop(int32_t ** sp)
{
    return *(--(*sp));
}

int32_t
stack_peek(int32_t ** sp, size_t offset)
/* offset=0 peeks TOS, offset=1 peeks NOS, etc. */
{
    return *((*sp)-offset-1);
}

uint8_t
next_code_byte(uint8_t * code, size_t * pc)
{
    return code[(*pc)++];
}

uint16_t
parse_label(uint8_t * code, size_t * pc)
{
    // TODO: Check for invalid label and die.
    uint16_t label = 0;
    uint8_t c;
    while ((c = code[(*pc)++]) != '\n') {
        label = label << 1;
        if (c == ' ') label++;
    }
    return label;
}

void
populate_labels(uint32_t * labels, uint8_t * code, size_t code_size)
{
    // TODO
}

void
process_imp_stack(uint8_t * code, size_t * pc, int32_t ** sp)
{
    switch (next_code_byte(code,pc)) {
        case ' ':
            /* Push number onto TOS. */
            {
                /* First, pick off the sign */
                int32_t sign = 0;
                switch (next_code_byte(code,pc)) {
                    case ' ' :  sign = 1;                       break;
                    case '\t':  sign = -1;                      break;
                    default  :  ws_die(pc, "expected sign");    break;
                }

                /* Now, construct the number and push to TOS. */
                /* I'm assuming the numbers are read MSb first. */
                int32_t temp, number = 0;
                while ((temp = next_code_byte(code,pc)) != '\n') {
                    if (temp == '\v') ws_die(pc, "non-binary digit in number");
                    number <<= 1;
                    if (temp == '\t') number++;
                }
                stack_push(sp, number*sign);
            }
            break;
        case '\n':
            /* Stack sub-command */
            {
                switch (next_code_byte(code,pc)) {
                        /* Duplicate the TOS. */
                    case ' ':
                        stack_push(sp, stack_peek(sp,0));
                        break;
                        /* Swap TOS and NOS. */
                    case '\t':
                        {
                            int32_t t1 = stack_pop(sp);
                            int32_t t2 = stack_pop(sp);
                            stack_push(sp, t1);
                            stack_push(sp, t2);
                        }
                        break;
                        /* Discard TOS. */
                    case '\n':
                        stack_pop(sp);
                        break;
                    default:
                        ws_die(pc, "malformed stack IMP");
                        break;
                }
            }
            break;
        default: ws_die(pc, "malformed stack IMP"); break;
    }
}

void
process_imp_arithmetic(uint8_t * code, size_t * pc, int32_t ** sp)
{
    int32_t temp;
    switch (next_code_byte(code,pc)) {
        case ' ':
            {
                switch (next_code_byte(code,pc)) {
                    case ' ':
                        /* Addition */
                        stack_push(sp, stack_pop(sp)+stack_pop(sp));
                        break;
                    case '\t':
                        /* Subtraction */
                        temp = stack_pop(sp);
                        stack_push(sp, stack_pop(sp)-temp);
                        break;
                    case '\n':
                        /* Multiplication */
                        stack_push(sp, stack_pop(sp)*stack_pop(sp));
                        break;
                    default:
                        ws_die(pc, "malformed arithmetic IMP");
                        break;
                }
            }
            break;
        case '\t':
            {
                switch (next_code_byte(code,pc)) {
                    case ' ':
                        /* Division */
                        temp = stack_pop(sp);
                        stack_push(sp, stack_pop(sp)/temp);
                        break;
                    case '\t':
                        /* Modulo */
                        temp = stack_pop(sp);
                        stack_push(sp, stack_pop(sp)%temp);
                        break;
                    default: ws_die(pc, "malformed arithmetic IMP"); break;
                }
            }
            break;
        default: ws_die(pc, "malformed arithmetic IMP"); break;
    }
}

void
process_imp_flowcontrol(uint8_t * code, size_t * pc, int32_t ** sp, uint32_t * labels,
                        uint32_t ** rsp)
{
    switch (next_code_byte(code,pc)) {
        case '\n':
            /* Technically another LF is required but we ignore it. */
            printf("\n");
            fflush(stdout);
            exit(EXIT_SUCCESS);
        case ' ':
            {
                switch (next_code_byte(code,pc)) {
                    case ' ':
                        /* Mark a location in the program. */
                        // TODO: Verify this is a label, but do nothing else.
                        labels[parse_label(code, pc)] = *pc;
                        break;
                    case '\t':
                        /* Call a subroutine. */
                        *((*rsp)++) = *pc;
                        *pc = labels[parse_label(code, pc)];
                        break;
                    case '\n':
                        /* Jump unconditionally to a label. */
                        *pc = labels[parse_label(code, pc)];
                        break;
                    default:
                        ws_die(pc, "malformed flow control IMP");
                        break;
                }
            }
            break;
        case '\t':
            {
                switch (next_code_byte(code,pc)) {
                    case ' ':
                        /* Jump to a label if TOS == 0 */
                        if (stack_peek(sp,0) == 0) *pc = labels[parse_label(code, pc)];
                        break;
                    case '\t':
                        /* Jump to a label if TOS < 0. */
                        if (stack_peek(sp,0) < 0) *pc = labels[parse_label(code, pc)];
                        break;
                    case '\n':
                        /* Return from subroutine. */
                        *pc = *(--(*rsp));
                        break;
                    default:
                        ws_die(pc, "malformed flow control IMP");
                        break;
                }
            }
            break;
        default:
            ws_die(pc, "malformed flow control IMP");
            break;
    }
}

void
process_imp_heap(uint8_t * code, size_t * pc, int32_t ** sp, int32_t ** hp)
{
    switch (next_code_byte(code,pc)) {
        case ' ' : /* Store to heap      */ *(*hp + *((*sp)-1)) = **sp; *sp -= 2; break;
        case '\t': /* Retrieve from heap */ **sp = *(*hp + **sp);                 break;
        default: ws_die(pc, "malformed heap IMP");                              break;
    }
}

void
process_imp_io(uint8_t * code, size_t * pc, int32_t ** sp, int32_t ** hp)
{
    switch (next_code_byte(code,pc)) {
        case ' ':
            /* Output */
            {
                switch (next_code_byte(code,pc)) {
                    case ' ' : /* Output character from TOS */ printf("%c", stack_pop(sp)); break;
                    case '\t': /* Output number from TOS    */ printf("%d", stack_pop(sp)); break;
                    default: ws_die(pc, "malformed output IMP");                          break;
                }
                fflush(stdout);
            }
            break;
        case '\t':
            /* Input */
            {
                while (stdin_empty()) continue;
                char c = getchar();
                switch (next_code_byte(code,pc)) {
                    case '\t': /* Input digit     */ c -= '0';                /* fallthrough */
                    case ' ' : /* Input character */ *(*hp + *((*sp)--)) = c; break;
                    default: ws_die(pc, "malformed input IMP");             break;
                }
            }
            break;
        default: ws_die(pc, "malformed i/o IMP"); break;
    }
}

int
main(int argc, char ** argv)
{
    /*
     * Process command line arguments
     */
    int c;
    FILE * input = NULL;
    while ((c = getopt(argc,argv,"i:h")) != -1) {
        switch (c) {
            case 'i':
                if ((input = fopen(optarg, "r")) == NULL) {
                    fprintf(stderr, "ERROR: %s: %s\n", optarg, strerror(errno));
                }
                break;
            case 'h':
                print_usage(argv);
                exit(EXIT_SUCCESS);
                break;
            default:
                break;
        }
    }
    if (input == NULL) {
        fprintf(stderr, "ERROR: Must specify a VVhitespace source file with -f flag.\n");
        print_usage(argv);
        exit(EXIT_FAILURE);
    }

    /*
     * Read just the VVhitespace source code into memory.
     * We will use the array indices as addresses for the virtual PC when jumping to labels.
     */
    size_t ws_code_size = 0;
    uint8_t temp_byte;
    while (fread(&temp_byte, 1, 1, input)) {
        if (temp_byte == ' ' || temp_byte == '\t' || temp_byte == '\n' || temp_byte == '\v') {
            ws_code_size++;
        }
    }
    rewind(input);
    uint8_t * ws_code_space = malloc(ws_code_size);
    ws_code_size = 0;
    while (fread(&temp_byte, 1, 1, input)) {
        if (temp_byte == ' ' || temp_byte == '\t' || temp_byte == '\n' || temp_byte == '\v') {
            ws_code_space[ws_code_size++] = temp_byte;
        }
    }
    fclose(input);

    /*
     * Setup a stack and heap.
     * Assume a 32-bit word size.
     */
    // TODO: Make everything 64-bit.
    int32_t * hp = malloc(HEAPSIZE*4);
    int32_t * sp = malloc(STACKSIZE*4);

    /* 
     * Setup the return stack and the label array.
     */
    uint32_t * rsp = malloc(RETURNSTACKSIZE*4);
    uint32_t labels[65536] = {0};
    populate_labels(labels, ws_code_space, ws_code_size);

    /*
     * Main Loop
     */

    size_t pc = 0; /* Virtual program counter. Operates in the ws_code_space[] address space. */
    while (1) {
        if (pc >= ws_code_size) {
            fprintf(stderr, "SIM_ERROR: PC Overrun\n    Requested PC: %lu\n    Max Address: %lu\n",
                pc, ws_code_size-1);
            exit(EXIT_FAILURE);
        }

        /* Decode the IMPs */
        switch (ws_code_space[pc++]) {
            case ' ':
                /* Stack Manipulation */
                process_imp_stack(ws_code_space, &pc, &sp);
                break;
            case '\n':
                /* Flow Control */
                process_imp_flowcontrol(ws_code_space, &pc, &sp, labels, &rsp);
                break;
            case '\t':
                /* Arithmetic, Heap Access, or I/O */
                {
                    switch (ws_code_space[pc++]) {
                        case ' ':
                            /* Arithmetic */
                            process_imp_arithmetic(ws_code_space, &pc, &sp);
                            break;
                        case '\t':
                            /* Heap Access */
                            process_imp_heap(ws_code_space, &pc, &sp, &hp);
                            break;
                        case '\n':
                            /* I/O */
                            process_imp_io(ws_code_space, &pc, &sp, &hp);
                            break;
                    }
                }
                break;
            default: ws_die(pc, "unexpected VTab"); break;
        }
    }

    printf("\n");
    printf("Program executed.\n");

    exit(EXIT_SUCCESS);
}
Commit	Line	Data
1adfc4f4 AT	1	/*
	2	* (c) 2019 Aaron Taylor <ataylor at subgeniuskitty dot com>
	3	* All rights reserved.
	4	*/
	5
	6	#include <stdio.h>
	7	#include <stdlib.h>
	8	#include <unistd.h>
	9	#include <string.h>
	10	#include <errno.h>
	11	#include <stdint.h>
	12	#include <sys/select.h>
	13	#include <getopt.h>
	14
	15	#define VERSION 1
	16
	17	#define STACKSIZE 1024
	18	#define HEAPSIZE 1024
	19	#define RETURNSTACKSIZE 1024
	20
	21	void
	22	print_usage(char ** argv)
	23	{
bf43fa3f	24	printf( "VVhitespace Interpreter v%d (www.subgeniuskitty.com)\n"
1adfc4f4 AT	25	"Usage: %s -i <file>\n"
1adfc4f4 AT	26	" -h Help (prints this message)\n"
bf43fa3f	27	" -i <file> Specify a VVhitespace source file to interpret.\n"
1adfc4f4 AT	28	, VERSION, argv[0]
	29	);
	30	}
	31
	32	int
	33	stdin_empty(void)
	34	{
	35	fd_set read_fds;
	36	FD_ZERO(&read_fds);
	37	FD_SET(STDIN_FILENO, &read_fds);
	38
	39	struct timeval timeout;
	40	timeout.tv_sec = 0;
	41	timeout.tv_usec = 0;
	42
	43	int retval = select(1, &read_fds, NULL, NULL, &timeout);
	44	/* retval could be -1. Ignoring that for now. */
	45	if (retval > 0) return 0;
	46	return 1;
	47	}
	48
	49	void
	50	ws_die(size_t * pc, char * msg)
	51	{
	52	printf("\n");
	53	printf("SIM_ERROR @ PC %lu: %s\n", *pc, msg);
	54	fflush(stdout);
	55	exit(EXIT_FAILURE);
	56	}
	57
	58	void
	59	stack_push(int32_t ** sp, int32_t word)
	60	{
	61	((sp)++) = word;
	62	}
	63
	64	int32_t
	65	stack_pop(int32_t ** sp)
	66	{
	67	return (--(sp));
	68	}
	69
	70	int32_t
	71	stack_peek(int32_t ** sp, size_t offset)
	72	/* offset=0 peeks TOS, offset=1 peeks NOS, etc. */
	73	{
	74	return ((sp)-offset-1);
	75	}
	76
	77	uint8_t
	78	next_code_byte(uint8_t * code, size_t * pc)
	79	{
	80	return code[(*pc)++];
	81	}
	82
	83	uint16_t
	84	parse_label(uint8_t * code, size_t * pc)
	85	{
bf43fa3f	86	// TODO: Check for invalid label and die.
1adfc4f4 AT	87	uint16_t label = 0;
	88	uint8_t c;
	89	while ((c = code[(*pc)++]) != '\n') {
	90	label = label << 1;
	91	if (c == ' ') label++;
	92	}
	93	return label;
	94	}
	95
bf43fa3f AT	96	void
	97	populate_labels(uint32_t * labels, uint8_t * code, size_t code_size)
	98	{
	99	// TODO
	100	}
	101
1adfc4f4 AT	102	void
	103	process_imp_stack(uint8_t * code, size_t * pc, int32_t ** sp)
	104	{
	105	switch (next_code_byte(code,pc)) {
	106	case ' ':
	107	/* Push number onto TOS. */
	108	{
	109	/* First, pick off the sign */
	110	int32_t sign = 0;
	111	switch (next_code_byte(code,pc)) {
	112	case ' ' : sign = 1; break;
	113	case '\t': sign = -1; break;
bf43fa3f	114	default : ws_die(pc, "expected sign"); break;
1adfc4f4 AT	115	}
	116
	117	/* Now, construct the number and push to TOS. */
	118	/* I'm assuming the numbers are read MSb first. */
	119	int32_t temp, number = 0;
	120	while ((temp = next_code_byte(code,pc)) != '\n') {
bf43fa3f	121	if (temp == '\v') ws_die(pc, "non-binary digit in number");
1adfc4f4 AT	122	number <<= 1;
	123	if (temp == '\t') number++;
	124	}
	125	stack_push(sp, number*sign);
	126	}
	127	break;
	128	case '\n':
	129	/* Stack sub-command */
	130	{
	131	switch (next_code_byte(code,pc)) {
	132	/* Duplicate the TOS. */
	133	case ' ':
	134	stack_push(sp, stack_peek(sp,0));
	135	break;
	136	/* Swap TOS and NOS. */
	137	case '\t':
	138	{
	139	int32_t t1 = stack_pop(sp);
	140	int32_t t2 = stack_pop(sp);
	141	stack_push(sp, t1);
	142	stack_push(sp, t2);
	143	}
	144	break;
	145	/* Discard TOS. */
	146	case '\n':
	147	stack_pop(sp);
	148	break;
bf43fa3f AT	149	default:
	150	ws_die(pc, "malformed stack IMP");
	151	break;
1adfc4f4 AT	152	}
	153	}
	154	break;
bf43fa3f	155	default: ws_die(pc, "malformed stack IMP"); break;
1adfc4f4 AT	156	}
	157	}
	158
	159	void
	160	process_imp_arithmetic(uint8_t * code, size_t * pc, int32_t ** sp)
	161	{
	162	int32_t temp;
	163	switch (next_code_byte(code,pc)) {
	164	case ' ':
	165	{
	166	switch (next_code_byte(code,pc)) {
	167	case ' ':
	168	/* Addition */
	169	stack_push(sp, stack_pop(sp)+stack_pop(sp));
	170	break;
	171	case '\t':
	172	/* Subtraction */
	173	temp = stack_pop(sp);
	174	stack_push(sp, stack_pop(sp)-temp);
	175	break;
	176	case '\n':
	177	/* Multiplication */
	178	stack_push(sp, stack_pop(sp)*stack_pop(sp));
	179	break;
bf43fa3f AT	180	default:
	181	ws_die(pc, "malformed arithmetic IMP");
	182	break;
1adfc4f4 AT	183	}
	184	}
	185	break;
	186	case '\t':
	187	{
	188	switch (next_code_byte(code,pc)) {
	189	case ' ':
	190	/* Division */
	191	temp = stack_pop(sp);
	192	stack_push(sp, stack_pop(sp)/temp);
	193	break;
	194	case '\t':
	195	/* Modulo */
	196	temp = stack_pop(sp);
	197	stack_push(sp, stack_pop(sp)%temp);
	198	break;
bf43fa3f	199	default: ws_die(pc, "malformed arithmetic IMP"); break;
1adfc4f4 AT	200	}
	201	}
	202	break;
bf43fa3f	203	default: ws_die(pc, "malformed arithmetic IMP"); break;
1adfc4f4 AT	204	}
	205	}
	206
	207	void
	208	process_imp_flowcontrol(uint8_t * code, size_t * pc, int32_t ** sp, uint32_t * labels,
	209	uint32_t ** rsp)
	210	{
	211	switch (next_code_byte(code,pc)) {
	212	case '\n':
	213	/* Technically another LF is required but we ignore it. */
	214	printf("\n");
	215	fflush(stdout);
	216	exit(EXIT_SUCCESS);
	217	case ' ':
	218	{
	219	switch (next_code_byte(code,pc)) {
	220	case ' ':
	221	/* Mark a location in the program. */
bf43fa3f	222	// TODO: Verify this is a label, but do nothing else.
1adfc4f4 AT	223	labels[parse_label(code, pc)] = *pc;
	224	break;
	225	case '\t':
	226	/* Call a subroutine. */
	227	((rsp)++) = *pc;
	228	*pc = labels[parse_label(code, pc)];
	229	break;
	230	case '\n':
	231	/* Jump unconditionally to a label. */
	232	*pc = labels[parse_label(code, pc)];
	233	break;
bf43fa3f AT	234	default:
	235	ws_die(pc, "malformed flow control IMP");
	236	break;
1adfc4f4 AT	237	}
	238	}
	239	break;
	240	case '\t':
	241	{
	242	switch (next_code_byte(code,pc)) {
	243	case ' ':
	244	/* Jump to a label if TOS == 0 */
	245	if (stack_peek(sp,0) == 0) *pc = labels[parse_label(code, pc)];
	246	break;
	247	case '\t':
	248	/* Jump to a label if TOS < 0. */
	249	if (stack_peek(sp,0) < 0) *pc = labels[parse_label(code, pc)];
	250	break;
	251	case '\n':
	252	/* Return from subroutine. */
	253	pc = (--(*rsp));
	254	break;
bf43fa3f AT	255	default:
	256	ws_die(pc, "malformed flow control IMP");
	257	break;
1adfc4f4 AT	258	}
	259	}
	260	break;
bf43fa3f AT	261	default:
	262	ws_die(pc, "malformed flow control IMP");
	263	break;
1adfc4f4 AT	264	}
	265	}
	266
	267	void
	268	process_imp_heap(uint8_t * code, size_t * pc, int32_t sp, int32_t hp)
	269	{
	270	switch (next_code_byte(code,pc)) {
	271	case ' ' : /* Store to heap / (hp + ((sp)-1)) = sp; sp -= 2; break;
	272	case '\t': /* Retrieve from heap / sp = (hp + *sp); break;
bf43fa3f	273	default: ws_die(pc, "malformed heap IMP"); break;
1adfc4f4 AT	274	}
	275	}
	276
	277	void
	278	process_imp_io(uint8_t * code, size_t * pc, int32_t sp, int32_t hp)
	279	{
	280	switch (next_code_byte(code,pc)) {
	281	case ' ':
	282	/* Output */
	283	{
	284	switch (next_code_byte(code,pc)) {
	285	case ' ' : /* Output character from TOS */ printf("%c", stack_pop(sp)); break;
	286	case '\t': /* Output number from TOS */ printf("%d", stack_pop(sp)); break;
bf43fa3f	287	default: ws_die(pc, "malformed output IMP"); break;
1adfc4f4 AT	288	}
	289	fflush(stdout);
	290	}
	291	break;
	292	case '\t':
	293	/* Input */
	294	{
	295	while (stdin_empty()) continue;
	296	char c = getchar();
	297	switch (next_code_byte(code,pc)) {
	298	case '\t': /* Input digit / c -= '0'; / fallthrough */
	299	case ' ' : /* Input character / (hp + ((*sp)--)) = c; break;
bf43fa3f	300	default: ws_die(pc, "malformed input IMP"); break;
1adfc4f4 AT	301	}
	302	}
	303	break;
bf43fa3f	304	default: ws_die(pc, "malformed i/o IMP"); break;
1adfc4f4 AT	305	}
	306	}
	307
1adfc4f4 AT	308	int
	309	main(int argc, char ** argv)
	310	{
	311	/*
	312	* Process command line arguments
	313	*/
	314	int c;
	315	FILE * input = NULL;
	316	while ((c = getopt(argc,argv,"i:h")) != -1) {
	317	switch (c) {
	318	case 'i':
	319	if ((input = fopen(optarg, "r")) == NULL) {
	320	fprintf(stderr, "ERROR: %s: %s\n", optarg, strerror(errno));
	321	}
	322	break;
	323	case 'h':
	324	print_usage(argv);
	325	exit(EXIT_SUCCESS);
	326	break;
	327	default:
	328	break;
	329	}
	330	}
	331	if (input == NULL) {
bf43fa3f	332	fprintf(stderr, "ERROR: Must specify a VVhitespace source file with -f flag.\n");
1adfc4f4 AT	333	print_usage(argv);
	334	exit(EXIT_FAILURE);
	335	}
	336
	337	/*
bf43fa3f	338	* Read just the VVhitespace source code into memory.
1adfc4f4 AT	339	* We will use the array indices as addresses for the virtual PC when jumping to labels.
	340	*/
	341	size_t ws_code_size = 0;
	342	uint8_t temp_byte;
	343	while (fread(&temp_byte, 1, 1, input)) {
bf43fa3f AT	344	if (temp_byte == ' ' \|\| temp_byte == '\t' \|\| temp_byte == '\n' \|\| temp_byte == '\v') {
	345	ws_code_size++;
	346	}
1adfc4f4 AT	347	}
	348	rewind(input);
	349	uint8_t * ws_code_space = malloc(ws_code_size);
	350	ws_code_size = 0;
	351	while (fread(&temp_byte, 1, 1, input)) {
bf43fa3f AT	352	if (temp_byte == ' ' \|\| temp_byte == '\t' \|\| temp_byte == '\n' \|\| temp_byte == '\v') {
	353	ws_code_space[ws_code_size++] = temp_byte;
	354	}
1adfc4f4 AT	355	}
	356	fclose(input);
	357
	358	/*
	359	* Setup a stack and heap.
	360	* Assume a 32-bit word size.
	361	*/
bf43fa3f	362	// TODO: Make everything 64-bit.
1adfc4f4 AT	363	int32_t * hp = malloc(HEAPSIZE*4);
	364	int32_t * sp = malloc(STACKSIZE*4);
	365
	366	/*
	367	* Setup the return stack and the label array.
	368	*/
	369	uint32_t * rsp = malloc(RETURNSTACKSIZE*4);
bf43fa3f AT	370	uint32_t labels[65536] = {0};
bf43fa3f AT	371	populate_labels(labels, ws_code_space, ws_code_size);
1adfc4f4 AT	372
	373	/*
	374	* Main Loop
	375	*/
	376
	377	size_t pc = 0; /* Virtual program counter. Operates in the ws_code_space[] address space. */
	378	while (1) {
	379	if (pc >= ws_code_size) {
bf43fa3f AT	380	fprintf(stderr, "SIM_ERROR: PC Overrun\n Requested PC: %lu\n Max Address: %lu\n",
bf43fa3f AT	381	pc, ws_code_size-1);
1adfc4f4 AT	382	exit(EXIT_FAILURE);
	383	}
	384
	385	/* Decode the IMPs */
	386	switch (ws_code_space[pc++]) {
	387	case ' ':
	388	/* Stack Manipulation */
	389	process_imp_stack(ws_code_space, &pc, &sp);
	390	break;
	391	case '\n':
	392	/* Flow Control */
	393	process_imp_flowcontrol(ws_code_space, &pc, &sp, labels, &rsp);
	394	break;
	395	case '\t':
	396	/* Arithmetic, Heap Access, or I/O */
	397	{
	398	switch (ws_code_space[pc++]) {
	399	case ' ':
	400	/* Arithmetic */
	401	process_imp_arithmetic(ws_code_space, &pc, &sp);
	402	break;
	403	case '\t':
	404	/* Heap Access */
	405	process_imp_heap(ws_code_space, &pc, &sp, &hp);
	406	break;
	407	case '\n':
	408	/* I/O */
	409	process_imp_io(ws_code_space, &pc, &sp, &hp);
	410	break;
	411	}
	412	}
	413	break;
bf43fa3f	414	default: ws_die(pc, "unexpected VTab"); break;
1adfc4f4 AT	415	}
	416	}
	417
	418	printf("\n");
	419	printf("Program executed.\n");
	420
	421	exit(EXIT_SUCCESS);
	422	}