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colorforth.c
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colorforth.c
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// The author disclaims copyright to this source code.
#include <ctype.h>
#include <inttypes.h>
#include <stdbool.h>
#include <stdint.h>
#include <stdlib.h>
#include <stdio.h>
#include <string.h>
enum opcode
{
OP_PRINT_TOS,
OP_DUP,
OP_OVER,
OP_SWAP,
OP_DROP,
OP_ADD,
OP_SUB,
OP_MUL,
OP_EQUAL,
OP_LESS,
OP_IF,
OP_BYE,
OP_WORDS,
OP_RETURN,
OP_TICK,
OP_EMIT,
OP_KEY,
OP_LOAD,
OP_STORE,
OP_CLOAD,
OP_CSTORE,
OP_CELL,
// call defined word
OP_CALL,
OP_TAIL_CALL,
OP_NUMBER,
OP_HERE,
OP_SYSTEM,
};
typedef size_t cell;
// terminal input buffer
struct tib
{
char buf[8];
size_t len;
};
struct code;
struct entry;
struct entry
{
char name[8];
cell name_len;
struct entry *prev;
cell code_len;
struct code
{
enum opcode opcode;
cell this;
} code[];
};
struct state
{
// circular stack
cell stack[8];
// stack position
int sp;
struct tib tib;
struct entry *dictionary;
struct entry *latest;
void *here;
};
static void
push(struct state *s, const cell n)
{
if (s->sp == (sizeof(s->stack) / sizeof(s->stack[0])) - 1)
{
s->sp = 0;
}
else
{
s->sp += 1;
}
s->stack[s->sp] = n;
}
static cell
pop(struct state *s)
{
const cell n = s->stack[s->sp];
if (s->sp == 0)
{
s->sp = (sizeof(s->stack) / sizeof(s->stack[0])) - 1;
}
else
{
s->sp -= 1;
}
return n;
}
static struct entry*
find_entry(struct state *s)
{
for (struct entry *entry = s->latest; entry; entry = entry->prev)
{
if (entry->name_len == s->tib.len && memcmp(entry->name, s->tib.buf, s->tib.len) == 0)
{
return entry;
}
}
return NULL;
}
// 'name' must be null-terminated.
static void
define_primitive(struct state *s, const char name[], const enum opcode opcode)
{
struct entry *entry = (struct entry*)&s->latest->code[s->latest->code_len];
entry->name_len = strlen(name);
memcpy(entry->name, name, entry->name_len);
entry->prev = s->latest;
entry->code[0].opcode = opcode;
entry->code[0].this = 0;
entry->code_len = 1;
s->latest = entry;
}
typedef void (*func)(struct state *s);
static void
define(struct state *s)
{
struct entry *entry = (struct entry*)&s->latest->code[s->latest->code_len];
entry->name_len = s->tib.len;
memcpy(entry->name, s->tib.buf, s->tib.len);
entry->prev = s->latest;
entry->code_len = 0;
s->latest = entry;
}
// TODO: use strtoul instead
// or, support signed with strtol
static bool
tib_to_number(struct state *s, cell *n_)
{
cell n = 0;
for (size_t i = 0; i < s->tib.len; ++i)
{
if (isdigit(s->tib.buf[i]))
{
n *= 10;
n += s->tib.buf[i] - '0';
}
else
{
return 0;
}
}
*n_ = n;
return 1;
}
static void
compile(struct state *s)
{
struct entry *entry = find_entry(s);
struct code *code = &s->latest->code[s->latest->code_len];
if (entry)
{
if (entry == s->latest)
{
code->opcode = OP_TAIL_CALL;
code->this = 0;
}
// FIXME: why a special case
else if (strcmp(entry->name, "if") == 0)
{
code->opcode = OP_IF;
code->this = 0;
}
// FIXME: why a special case
else if (strcmp(entry->name, ";") == 0)
{
code->opcode = OP_RETURN;
code->this = 0;
}
else
{
code->opcode = OP_CALL;
code->this = (cell)entry;
}
s->latest->code_len += 1;
}
else
{
// try to interpret as an unsigned decimal number
cell n = 0;
if (tib_to_number(s, &n))
{
// compile number
code->opcode = OP_NUMBER;
code->this = n;
s->latest->code_len += 1;
}
else
{
printf("? ");
}
}
}
static void
execute_(struct state *s, struct entry *entry)
{
//~ printf("%s\t%li\n", entry->name, entry->code_len);
for (struct code *pc = &entry->code[0]; pc < &entry->code[entry->code_len]; ++pc)
{
switch (pc->opcode)
{
case OP_PRINT_TOS:
{
printf("%"PRIiFAST32" ", pop(s));
fflush(stdout);
break;
}
case OP_DUP:
{
push(s, s->stack[s->sp]);
break;
}
case OP_OVER:
{
const cell n1 = pop(s);
const cell n2 = pop(s);
push(s, n2);
push(s, n1);
push(s, n2);
break;
}
case OP_SWAP:
{
const cell n1 = pop(s);
const cell n2 = pop(s);
push(s, n1);
push(s, n2);
break;
}
case OP_DROP:
{
pop(s);
break;
}
case OP_ADD:
{
const cell n1 = pop(s);
const cell n2 = pop(s);
push(s, n1 + n2);
break;
}
case OP_SUB:
{
const cell n1 = pop(s);
const cell n2 = pop(s);
push(s, n1 - n2);
break;
}
case OP_MUL:
{
const cell n1 = pop(s);
const cell n2 = pop(s);
push(s, n1 * n2);
break;
}
case OP_EQUAL:
{
const cell n1 = pop(s);
const cell n2 = pop(s);
push(s, n1 == n2);
break;
}
case OP_LESS:
{
const cell n1 = pop(s);
const cell n2 = pop(s);
push(s, n2 < n1);
break;
}
case OP_IF:
{
const cell n = pop(s);
if (!n)
{
// doesn't work, because this is only causing if to return, not foo.
// fixed with an exception in compile
++pc;
}
break;
}
case OP_BYE:
{
exit(0);
break;
}
case OP_WORDS:
{
for (struct entry *entry = s->latest; entry; entry = entry->prev)
{
printf("%.*s ", (int)entry->name_len, entry->name);
}
break;
}
case OP_RETURN:
{
pc = &entry->code[entry->code_len];
break;
}
case OP_TICK:
{
break;
}
case OP_EMIT:
{
putchar((char)pop(s));
break;
}
case OP_KEY:
{
push(s, (char)getchar());
break;
}
case OP_LOAD:
{
push(s, *(cell*)pop(s));
break;
}
case OP_STORE:
{
cell *ptr = (cell*)pop(s);
cell n = pop(s);
*ptr = n;
break;
}
case OP_CLOAD:
{
push(s, *(char*)pop(s));
break;
}
case OP_CSTORE:
{
char *ptr = (char*)pop(s);
char n = pop(s);
*ptr = n;
break;
}
case OP_CELL:
{
push(s, sizeof(cell));
break;
}
case OP_CALL:
{
struct entry *entry_ = (struct entry*)pc->this;
// recursion
execute_(s, entry_);
break;
}
case OP_TAIL_CALL:
{
pc = &entry->code[-1];
break;
}
case OP_NUMBER:
{
push(s, pc->this);
break;
}
case OP_HERE:
{
push(s, (cell)&s->here);
break;
}
case OP_SYSTEM:
{
push(s, system((char*)pop(s)));
break;
}
default:
{
puts("unknown opcode");
exit(1);
}
}
}
}
static void
execute(struct state *s)
{
struct entry *entry = find_entry(s);
if (entry)
{
execute_(s, entry);
}
else
{
// try to interpret as an unsigned decimal number
cell n = 0;
if (tib_to_number(s, &n))
{
push(s, n);
}
else
{
printf("? ");
}
}
}
static void
comment(struct state *s)
{
}
struct state*
colorforth_newstate(void)
{
struct state *state = calloc(1, sizeof(*state));
state->dictionary = calloc(1, 4096);
state->latest = state->dictionary;
state->here = calloc(1, 4096);
return state;
}
int
main(int argc, char *argv[])
{
struct state *state = colorforth_newstate();
static const struct primitive_map
{
const char *name;
const enum opcode opcode;
} primitive_map[] =
{
{".", OP_PRINT_TOS},
{"dup", OP_DUP},
{"over", OP_OVER},
{"swap", OP_SWAP},
{"drop", OP_DROP},
{"+", OP_ADD},
{"-", OP_SUB},
{"*", OP_MUL},
{"=", OP_EQUAL},
{"<", OP_LESS},
{"if", OP_IF},
{"bye", OP_BYE},
{"words", OP_WORDS},
{";", OP_RETURN},
{"'", OP_TICK},
{"emit", OP_EMIT},
{"key", OP_KEY},
{"@", OP_LOAD},
{"!", OP_STORE},
{"c@", OP_CLOAD},
{"c!", OP_CSTORE},
{"cell", OP_CELL},
{"here", OP_HERE},
{"system", OP_SYSTEM},
};
for (unsigned int i = 0; i < sizeof(primitive_map) / sizeof(primitive_map[0]); ++i)
{
define_primitive(state, primitive_map[i].name, primitive_map[i].opcode);
}
func color = execute;
while (1)
{
state->tib.len = 0;
bool reading_word = true;
while (reading_word)
{
int c;
switch (c = getchar())
{
case ':':
{
color = define;
break;
}
case '^':
{
if (color == execute)
{
struct code *code = &state->latest->code[state->latest->code_len];
code->opcode = OP_NUMBER;
code->this = pop(state);
state->latest->code_len += 1;
}
color = compile;
break;
}
case '~':
{
color = execute;
break;
}
case '(':
{
color = comment;
break;
}
case '\n':
case ' ':
case '\t':
{
if (state->tib.len == 0)
{
// Strip leading whitespace.
}
else
{
// Have word.
color(state);
reading_word = false;
}
break;
}
case EOF:
{
//~ exit(0);
break;
}
default:
{
if (state->tib.len < sizeof(state->tib.buf))
{
state->tib.buf[state->tib.len++] = c;
}
break;
}
}
}
}
return 0;
}