From 0a9fa35c45523a0e397d2ecd2dd5cd603908c52d Mon Sep 17 00:00:00 2001
From: Mart Lubbers <mart@martlubbers.net>
Date: Thu, 25 Aug 2016 16:33:10 +0200
Subject: [PATCH] clean up and speed up

---
 bf.c | 68 ++++++++++++++++++++++++++----------------------------------
 1 file changed, 29 insertions(+), 39 deletions(-)

diff --git a/bf.c b/bf.c
index 23aa2da..af9f001 100644
--- a/bf.c
+++ b/bf.c
@@ -1,6 +1,13 @@
 #include <stdlib.h>
 #include <string.h>
 #include <stdio.h>
+#include <errno.h>
+
+#define die(s, as...) {fprintf(stderr, s, ## as); return EXIT_FAILURE;}
+#define check_fail(v, s, f) if((v) == f) die("%s(): %s\n", s, strerror(errno))
+#define check_null(v, s) check_fail(v, s, NULL)
+
+#define INITIALBUFSIZE 2
 
 struct nest {
 	long pos;
@@ -9,51 +16,37 @@ struct nest {
 
 int main(int argc, char *argv[])
 {
-	size_t offset, stacksize;
+	size_t offset, stacksize, depth;
 	char *buf, *ptr;
 	struct nest *temp, *stack;
 	FILE *in;
 
 	if(argc != 2){
-		fprintf(stderr, "Usage: %s PROGRAM\n", argv[0]);
-		return EXIT_FAILURE;
+		die("Usage: %s PROGRAM\n", argv[0]);
 	}
    
-	if((buf = malloc(stacksize = 1)) == NULL){
-		perror("malloc");
-		return EXIT_FAILURE;
-	}
-	buf[0] = 0;
+	check_null(in = fopen(argv[1], "r"), "fopen");
+	check_null(buf = calloc(stacksize = INITIALBUFSIZE, 1), "calloc");
 	ptr = buf;
 
-	if((in = fopen(argv[1], "r")) == NULL){
-		perror("fopen");
-		return EXIT_FAILURE;
-	}
-
 	while(1){
 		switch(fgetc(in)){
 			case EOF:
 				free(buf);
+				check_fail(fclose(in), "fclose", -1);
 				return EXIT_SUCCESS;
 			case '>':
-				++ptr;
-				if(ptr >= buf+stacksize){
+				if(++ptr >= buf+stacksize){
 					offset = ptr-buf;
-					if((buf = realloc(buf, stacksize *= 2)) == NULL){
-						perror("realloc");
-						return EXIT_FAILURE;
-					}
+					check_null(buf = realloc(buf, stacksize *=2), "realloc");
 					ptr = buf+offset;
 					memset(ptr, 0, stacksize/2);
 				}
 				break;
 			case '<':
-				if(ptr == buf){
-					fprintf(stderr, "There is no stack position -1...\n");
-					return EXIT_FAILURE;
+				if(ptr-- == buf){
+					die("There is no stack position -1\n");
 				}
-				--ptr;
 				break;
 			case '+':
 				++*ptr;
@@ -70,30 +63,27 @@ int main(int argc, char *argv[])
 			case '[':
 				if(*ptr){
 					temp = stack;
-					if((stack = malloc(sizeof(struct nest))) == NULL){
-						perror("realloc");
-						return EXIT_FAILURE;
-					}
+					check_null(stack = malloc(sizeof(struct nest)), "malloc");
 					stack->next = temp;
-					if((stack->pos = ftell(in)) == -1){
-						perror("ftell");
-						return EXIT_FAILURE;
-					}
+					check_fail(stack->pos = ftell(in), "ftell", -1);
 				} else {
-					while(fgetc(in) != ']');
+					depth = 1;
+					while(depth > 0){
+						switch(fgetc(in)){
+							case ']':
+								depth--;
+								break;
+							case '[':
+								depth++;
+						}
+					}
 				}
 				break;
 			case ']':
-				if(fseek(in, stack->pos-1, SEEK_SET) == -1){
-					perror("fseek");
-					return EXIT_FAILURE;
-				}
+				check_fail(fseek(in, stack->pos-1, SEEK_SET), "fseek", -1);
 				temp = stack;
 				stack = stack->next;
 				free(temp);
-				break;
-			default:
-				break;
 		}
 	}
 }
-- 
2.20.1