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embed.c
180 lines (169 loc) · 5.83 KB
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embed.c
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/* H2 Forth Virtual Machine, Richard James Howe, 2017-2019, MIT License */
#include <assert.h>
#include <errno.h>
#include <stdarg.h>
#include <stdint.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#define STK (64)
#define USE_HEX_IN (0)
#define USE_HEX_OUT (1)
typedef uint16_t m_t;
typedef int16_t s_t;
typedef uint32_t d_t;
typedef struct forth_t { m_t m[32768], vs[STK], rs[STK], pc, t, rp, sp, cpu; } forth_t;
typedef int (*cb)(forth_t *h, void *param);
static inline size_t cells(forth_t const * const h) {
assert(h);
return sizeof(h->m)/sizeof(h->m[0]);
}
static void die(const char *fmt, ...) {
assert(fmt);
va_list arg;
va_start(arg, fmt);
vfprintf(stderr, fmt, arg);
va_end(arg);
fputc('\n', stderr);
exit(EXIT_FAILURE);
}
static FILE *fopen_or_die(const char *file, const char *mode) {
assert(file && mode);
FILE *h = NULL;
errno = 0;
if (!(h = fopen(file, mode)))
die("file open %s (mode %s) failed: %s", file, mode, strerror(errno));
return h;
}
static int save(forth_t *h, const char *name, const size_t start, const size_t length) {
assert(h);
if (!name || !(((length - start) <= length) && ((start + length) <= cells(h))))
return -69; /* open-file IOR */
FILE *out = fopen(name, "wb");
if (!out)
return -69; /* open-file IOR */
int r = 0;
for (size_t i = start; i < length; i++) {
if (USE_HEX_OUT) {
fprintf(out, "%02x%02x\n", ((unsigned)(h->m[i] >> 8) & 255u), (unsigned)(h->m[i] >> 0) & 255u);
} else {
if (fputc(h->m[i]&255, out) < 0 || fputc(h->m[i]>>8, out) < 0)
r = -76; /* write-file IOR */
}
}
return fclose(out) < 0 ? -62 /* close-file IOR */ : r;
}
static int load(forth_t *h, const char *name) {
assert(h && name);
FILE *input = fopen_or_die(name, "rb");
long r = 0;
for (size_t i = 0; i < cells(h); i++, r = i) {
if (USE_HEX_IN) {
unsigned d = 0;
if (fscanf(input, "%x", &d) != 1) {
r = -1;
break;
}
h->m[i] = d;
} else {
int c1 = 0, c2 = 0;
if ((c1 = fgetc(input)) < 0 || (c2 = fgetc(input)) < 0)
break;
h->m[i] = ((c1 & 0xffu)) | ((c2 & 0xffu) << 8u);
}
}
fclose(input);
return r < 64 ? -70 /* read-file IOR */ : 0; /* minimum size checks, 128 bytes */
}
static inline void trace(FILE *out, m_t opt, m_t *m, m_t pc, m_t instruction, m_t t, m_t rp, m_t sp) {
(void)m;
if (!(opt & 1))
return;
fprintf(out, "[ %4x %4x %4x %2x %2x ]\n", pc-1, instruction, t, rp, sp);
}
static int run(forth_t *h, m_t opt, FILE *in, FILE *out, const char *block, cb func, void *param) {
assert(h && in && out);
static const m_t delta[] = { 0, 1, -2, -1 };
const m_t l = cells(h);
m_t *const m = h->m, *const vs = h->vs, *const rs = h->rs;
m_t pc = h->pc, t = h->t, rp = h->rp, sp = h->sp, cpu = h->cpu, r = 0;
for (;;) {
const m_t instruction = m[pc++];
trace(out, opt, m, pc, instruction, t, rp, sp);
if ((r = -!(sp < STK && rp < STK && pc < l))) /* critical error */
goto finished;
if (0x8000 & instruction) { /* literal */
vs[++sp % STK] = t;
t = instruction & 0x7FFF;
} else if ((0xE000 & instruction) == 0x6000) { /* ALU */
m_t n = vs[sp % STK], T = t;
pc = (instruction & 0x10) ? rs[rp % STK] >> 1 : pc;
switch ((instruction >> 8u) & 0x1f) {
case 0: break;
case 1: T = n; break;
case 2: T += n; break;
case 3: T &= n; break;
case 4: T |= n; break;
case 5: T ^= n; break;
case 6: T = ~t; break;
case 7: T = -(t == n); break;
case 8: T = -((s_t)n < (s_t)t); break;
case 9: T = n >> t; break;
case 10: T--; break;
case 11: T = rs[rp % STK]; break;
case 12: T = m[(t>>1)%l]; break;
case 13: T = n << t; break;
case 14: T = sp; break;
case 15: T = -(n < t); break;
case 16: cpu = t; T = n; break;
case 17: T = cpu; break;
case 18: T = rp; break;
case 19: T = -(t == 0); break;
case 20: T = 0xD1ED; /* CPU-ID */ break;
case 21: T = instruction & 0x7FFF; break; /* lit: internal use only */
/* 22: UNUSED */
/* 23: UNUSED */
/* 24: UNUSED */
/* Hosted instructions only */
case 25: if (opt & 2) { T = save(h, block, n>>1, ((d_t)T+1)>>1); } break;
case 26: if (opt & 2) { T = fputc(t, out); } break;
case 27: if (opt & 2) { T = fgetc(in); } break;
case 28: if (opt & 2) { if (rs[rp % STK]) { rs[rp % STK] = 0; sp--; r = t; t = n; goto finished; }; T = t; } break;
case 29: if (opt & 2) { T = opt; opt = T; } break;
case 30: if (opt & 2) { if (func) { T = func(h, param); } else { pc=4; T=21; } } break;
/* 31: UNUSED */
default: if (opt & 2) { pc=4; T=21; } break;
}
sp += delta[ instruction & 0x3];
rp += delta[(instruction >> 2) & 0x3];
if (instruction & 0x80)
vs[sp % STK] = t;
if (instruction & 0x40)
rs[rp % STK] = t;
if (instruction & 0x20)
m[(t >> 1) % l] = n;
t = T;
} else if (0x4000 & instruction) { /* call */
rs[++rp % STK] = pc << 1;
pc = instruction & 0x1FFF;
} else if (0x2000 & instruction) { /* 0branch */
pc = !t ? instruction & 0x1FFF : pc;
t = vs[sp-- % STK];
} else { /* branch */
pc = instruction & 0x1FFF;
}
}
finished: h->pc = pc, h->t = t, h->rp = rp, h->sp = sp, h->cpu = cpu;
return (s_t)r;
}
int main(int argc, char **argv) {
static forth_t h = { .m = { 0 }, .vs = { 0 }, .rs = { 0 } };
if (argc > 4)
die("usage: %s [in.blk] [out.blk] [file.fth]", argv[0]);
if (load(&h, argc < 2 ? "embed.blk" : argv[1]) < 0)
die("embed: load failed");
FILE *in = argc <= 3 ? stdin : fopen_or_die(argv[3], "rb");
if (run(&h, 2, in, stdout, argc < 3 ? NULL : argv[2], NULL, NULL))
die("embed: run failed");
return 0; /* exiting takes care of closing files, freeing memory */
}