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// Copyright (C) 2023 Dzshy <dzshy@outlook.com>. All Rights Reserved.
// Licensed under Non-Profit Open Software License ("Non-Profit OSL") 3.0.
#include <stdint.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <fcntl.h>
#include <sys/mman.h>
#include <sys/stat.h>
#include "crc32.h"
#include "htable.h"
#define LOGGER(s, ...) \
do { \
fprintf(stderr, s "\n", ##__VA_ARGS__); \
} while (0)
uint8_t *pbuf;
uint8_t *nbuf;
long nsz, psz;
static const int INIT_SZ = 128;
typedef struct {
long key;
long val;
} JmpTblEntry;
static bool jmptbl_eq(void *x, void *y)
{
long *a = x, *b = y;
return *a == *b;
}
static uint32_t jmptbl_hash(void *k) { return crc32(0, k, sizeof(long)); }
HTable jmptbl;
struct listnode {
struct listnode *next;
long val;
};
typedef struct {
struct listnode *head;
} Stack;
void stack_push(Stack *s, long val)
{
struct listnode *n = malloc(sizeof(struct listnode));
n->next = s->head;
n->val = val;
s->head = n;
}
long *stack_top(Stack *s)
{
if (s->head == NULL)
return NULL;
return &(s->head->val);
}
void stack_pop(Stack *s)
{
if (s->head == NULL)
return;
struct listnode *next = s->head->next;
free(s->head);
s->head = next;
}
void buildjmptable(char *buf, long len)
{
Stack s = {0};
htable_init(&jmptbl, sizeof(JmpTblEntry), -1, jmptbl_hash, jmptbl_eq);
for (long i = 0; i < len; i++) {
if (buf[i] == '[') {
stack_push(&s, i);
} else if (buf[i] == ']') {
long j = *stack_top(&s);
stack_pop(&s);
JmpTblEntry e1 = {i, j};
JmpTblEntry e2 = {j, i};
htable_insert(&jmptbl, &e1);
htable_insert(&jmptbl, &e2);
}
}
}
static long tbllookup(long pos)
{
JmpTblEntry *iter = htable_find(&jmptbl, &pos);
return iter->val;
}
void ensurespc_impl(uint8_t **buf, long *cursz, long ptr)
{
if (ptr > *cursz) {
*buf = realloc(*buf, ptr * 2);
memset((*buf) + (*cursz), 0, 2 * ptr - (*cursz));
*cursz = ptr * 2;
}
}
void ensurespc(long ptr)
{
if (ptr >= 0) {
ensurespc_impl(&pbuf, &psz, ptr);
} else {
ensurespc_impl(&nbuf, &nsz, -ptr);
}
}
uint8_t getdata(long ptr)
{
ensurespc(ptr);
if (ptr >= 0)
return pbuf[ptr];
else
return nbuf[-ptr];
}
void setdata(long ptr, uint8_t val)
{
ensurespc(ptr);
if (ptr >= 0)
pbuf[ptr] = val;
else
nbuf[-ptr] = val;
}
void interp(char *prog, long prog_sz)
{
long prog_p = 0;
long data_p = 0;
nbuf = malloc(INIT_SZ);
pbuf = malloc(INIT_SZ);
nsz = INIT_SZ;
psz = INIT_SZ;
memset(nbuf, 0, INIT_SZ);
memset(pbuf, 0, INIT_SZ);
while (prog_p < prog_sz) {
switch (prog[prog_p]) {
case '>':
data_p++;
break;
case '<':
data_p--;
break;
case '+':
setdata(data_p, getdata(data_p) + 1);
break;
case '-':
setdata(data_p, getdata(data_p) - 1);
break;
case '.':
putchar(getdata(data_p));
break;
case ',':
setdata(data_p, getchar());
break;
case '[':
if (getdata(data_p) == 0) {
prog_p = tbllookup(prog_p);
}
break;
case ']':
if (getdata(data_p) != 0) {
prog_p = tbllookup(prog_p);
}
break;
default:
break;
}
prog_p++;
}
}
int main(int argc, char **argv)
{
if (argc < 2) {
LOGGER("invalid args");
return EXIT_FAILURE;
}
int fd = open(argv[1], O_RDONLY);
if (fd < 0) {
return EXIT_FAILURE;
}
struct stat fst;
int ret = fstat(fd, &fst);
if (ret != 0) {
LOGGER("error: failed to get file stat");
return EXIT_FAILURE;
}
long filesz = fst.st_size;
char *prog = malloc(filesz);
FILE *fp = fdopen(fd, "r");
if (fp == NULL) {
LOGGER("error opening file");
exit(-1);
}
size_t read = fread(prog, 1, filesz, fp);
if (read < filesz) {
LOGGER("erro reading");
exit(-1);
}
buildjmptable(prog, filesz);
interp(prog, filesz);
return EXIT_SUCCESS;
}
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