Add example

.gitignore

@@ -0,0 +1,2 @@
+*.o
+xrle

Makefile

@@ -0,0 +1,5 @@
+CFLAGS := -Wall -Wextra -std=c99 -pedantic -Og -g3
+
+all: xrle
+xrle: xrle.o main.o
+	$(CC) $(CFLAGS) -o $@ $^ $(LDFLAGS) $(LDLIBS)

main.c

@@ -0,0 +1,95 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include "xrle.h"
+
+void *read_file(const char *file, size_t *sz)
+{
+	FILE *f;
+	void *ret = NULL;
+
+	f = fopen(file, "rb");
+	if(f == NULL)
+		goto out;
+
+	fseek(f, 0, SEEK_END);
+	*sz = ftell(f);
+	fseek(f, 0, SEEK_SET);
+
+	ret = malloc(*sz);
+	if(ret != NULL)
+		fread(ret, 1, *sz, f);
+
+	fclose(f);
+
+out:
+	return ret;
+}
+
+
+int main(int argc, char *argv[])
+{
+	const char *file;
+	char *in, *out;
+	size_t insz, outsz;
+
+	if(argc != 3 || argv[1][0] != '-')
+	{
+		fprintf(stderr, "Usage: xrle [-c|-d] file > out\n");
+		return 1;
+	}
+
+	if(argv[1][1] != 'c' && argv[1][1] != 'd')
+	{
+		fprintf(stderr, "Unknown option '%s'\n", argv[1]);
+		return 1;
+	}
+
+	file = argv[2];
+	in = read_file(file, &insz);
+	if(in == NULL)
+	{
+		fprintf(stderr, "An error occured\n");
+		return 1;
+	}
+
+	if(argv[1][1] == 'c')
+	{
+		out = malloc(xrle_max_out(insz));
+		if(out == NULL)
+		{
+			fprintf(stderr, "Unable to allocate memory\n");
+			return 1;
+		}
+
+		outsz = xrle_compress(out, in, insz);
+		for(size_t i = 0; i < outsz; i++)
+			putc(out[i], stdout);
+
+		fflush(stdout);
+		free(out);
+
+	}
+	else
+	{
+		outsz = xrle_getsz(in);
+		out = malloc(outsz + 8);
+		if(out == NULL)
+		{
+			fprintf(stderr, "Unable to allocate %lu bytes of memory\n", outsz);
+			return 1;
+		}
+
+		outsz = xrle_decompress(out, in, insz);
+		for(size_t i = 0; i < outsz; i++)
+			putc(out[i], stdout);
+
+		fflush(stdout);
+		free(out);
+
+	}
+
+	fprintf(stderr, "%lu --> %lu, %f%%\n", insz, outsz, ((float)outsz/(float)insz)*100.0f);
+	free(in);
+
+	return 0;
+}

xrle.c

@@ -25,6 +25,14 @@
  */
 
 /*
+ * 	Files created with this tool are not endian agnostic.
+ *
+ * 	Header:
+ *           32 bits
+ *      +--------------+
+ *      | size of file |
+ *      +--------------+
+ *
  *      Format:
  *           32 bits	      32 bits                    64 bits
  *      +----------------+---------------+----------+----------------+
@@ -36,15 +44,18 @@
 #include <stdint.h>
 #include <string.h>
 
-#define U64 uint64_t
-#define U32 uint32_t
+typedef uint64_t U64;
+typedef uint32_t U32;
 
 size_t xrle_compress(void * out,const void * in,size_t in_size)
 {
 	U64 *in_pos = (U64 *) in,*out_pos = (U64 *) out;
 	U32 tail = in_size & 7,*descr,repeat;
 	U64 *in_limit = (U64 *)((char *)in + in_size - tail),previous,next;
 
+	*out_pos = in_size;
+	out_pos++;
+
 	if(in_size < 16){
 		memcpy(out,in,in_size);
 		return in_size;
@@ -85,13 +96,22 @@ size_t xrle_compress(void * out,const void * in,size_t in_size)
 	return (char *)out_pos - (char *)out + tail;
 }
 
+U32 xrle_getsz(const void * in)
+{
+	U32 expected;
+	memcpy(&expected, in, sizeof(expected));
+	return expected;
+}
+
 size_t xrle_decompress(void * out,const void * in,size_t in_size)
 {
 
 	U64 *in_pos = (U64 *) in,*out_pos = (U64 *) out,word,tmp;
 	U32 tail = in_size & 7,lit_len,repeat,i;
 	U64 *in_limit = (U64 *)((char *)in + in_size - tail);
 
+	in_pos++;
+
 	if(in_size < 16){
 		memcpy(out,in,in_size);
 		return in_size;

xrle.h

@@ -39,6 +39,8 @@
  */
 size_t xrle_compress(void * out,const void * in,size_t in_size);
 
+size_t xrle_getsz(const void * in);
+
 /*
  * in: buffer to decompress
  * out: buffer to store decompressed data
@@ -53,4 +55,4 @@ size_t xrle_compress(void * out,const void * in,size_t in_size);
 size_t xrle_decompress(void * out,const void * in,size_t in_size);
 
 /* This macro returns the maximum size of compressed data in bytes */
-#define xrle_max_out(A) ((A) + 8)
+#define xrle_max_out(A) ((A) + 8 + 4)