From fb317a3cafd7db4b3c60768eee8549dea9b54ce1 Mon Sep 17 00:00:00 2001
From: Tom Smeding <tom.smeding@gmail.com>
Date: Sun, 15 Apr 2018 21:30:07 +0200
Subject: Add bfinter_simple, which is slow but "obviously correct"

---
 .gitignore       |   2 +
 Makefile         |   2 +-
 bfinter_simple.c | 113 +++++++++++++++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 116 insertions(+), 1 deletion(-)
 create mode 100644 bfinter_simple.c

diff --git a/.gitignore b/.gitignore
index 4b8ea84..4af4306 100644
--- a/.gitignore
+++ b/.gitignore
@@ -1,5 +1,7 @@
 bfinter
 bfinter2
+bfinter_simple
 *.o
 *.dSYM
 *.bf
+compile_commands.json
diff --git a/Makefile b/Makefile
index 0081677..4638c48 100644
--- a/Makefile
+++ b/Makefile
@@ -1,7 +1,7 @@
 CC = gcc
 CFLAGS = -Wall -Wextra -O2 -std=c11 -fwrapv -D_POSIX_C_SOURCE
 
-TARGETS = bfinter bfinter2
+TARGETS = bfinter bfinter2 bfinter_simple
 
 .PHONY: all clean remake
 
diff --git a/bfinter_simple.c b/bfinter_simple.c
new file mode 100644
index 0000000..58174fb
--- /dev/null
+++ b/bfinter_simple.c
@@ -0,0 +1,113 @@
+#define _GNU_SOURCE
+#include <stdio.h>
+#include <stdlib.h>
+#include <stdbool.h>
+#include <stdint.h>
+#include <unistd.h>
+#include <fcntl.h>
+#include <sys/stat.h>
+#include <assert.h>
+
+
+static char* readfile(const char *fname, size_t *length){
+	int fd = open(fname, O_RDONLY);
+	if (fd < 0) {
+		perror("open");
+		exit(1);
+	}
+
+	struct stat statbuf;
+	if (fstat(fd, &statbuf) < 0) {
+		perror("stat");
+		exit(1);
+	}
+
+	*length = statbuf.st_size;
+
+	FILE *f = fdopen(fd, "r");
+	if (!f) {
+		fprintf(stderr, "Cannot open file '%s'\n", fname);
+		exit(1);
+	}
+	char *mem = malloc(*length + 1);
+	assert(fread(mem, 1, *length, f) == *length);
+	fclose(f);
+
+	return mem;
+}
+
+static void dump(const uint8_t *mem, size_t memsize, size_t mp) {
+	size_t low = 0, high = memsize - 1;
+	while (low < mp && mem[low] == 0) low++;
+	while (high > mp && mem[high] == 0) high--;
+	for (size_t i = low; i <= high; i++) {
+		if (i == mp) fprintf(stderr, "\x1B[4m");
+		fprintf(stderr, "%3u ", mem[i]);
+		if (i == mp) fprintf(stderr, "\x1B[0m");
+	}
+	fprintf(stderr, "\n");
+}
+
+
+int main(int argc, char **argv) {
+	if (argc != 2) {
+		fprintf(stderr, "Usage: %s <file.bf>\n", argv[0]);
+		return 1;
+	}
+
+	size_t srclen;
+	char *source = readfile(argv[1], &srclen);
+
+	size_t *jm = malloc(srclen * sizeof(size_t));
+	size_t *stk = malloc(srclen * sizeof(size_t));
+	size_t stklen = 0;
+	for (size_t i = 0; i < srclen; i++) {
+		if (source[i] == '[') {
+			stk[stklen++] = i;
+		} else if (source[i] == ']') {
+			if (stklen == 0) {
+				fprintf(stderr, "Too many ']'\n");
+				return 1;
+			}
+			jm[stk[stklen-1]] = i;
+			jm[i] = stk[stklen-1];
+			stklen--;
+		}
+	}
+	if (stklen > 0) {
+		fprintf(stderr, "Too many '['\n");
+		return 1;
+	}
+
+	free(stk);
+
+	const size_t memsize = 60000;
+	uint8_t *mem = calloc(memsize, 1);
+	size_t mp = memsize / 2;
+	bool stop = false;
+	for (size_t i = 0; i < srclen && !stop; i++) {
+		switch (source[i]) {
+			case '+': mem[mp]++; break;
+			case '-': mem[mp]--; break;
+			case '>': mp++; break;
+			case '<': mp--; break;
+			case ',': mem[mp] = getchar(); break;
+			case '.': putchar(mem[mp]); break;
+			case '[': if (!mem[mp]) i = jm[i]; break;
+			case ']': if (mem[mp]) i = jm[i]; break;
+			case '`': stop = true; break;
+			case '$': fprintf(stderr, "CRASH\n"); stop = true; break;
+			// case '*': usleep(5000000); break;
+			case '*': fprintf(stderr, "CHANGE\n"); source[i] = '`'; break;
+			default: continue;
+		}
+
+		// dump(mem, memsize, mp);
+	}
+
+	dump(mem, memsize, mp);
+
+	free(mem);
+	free(source);
+	free(jm);
+}
-- 
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