add basic example for compiling upkr to a c library

c_library/upkr.c

@@ -0,0 +1,99 @@
+#include "upkr.h"
+#include <stdio.h>
+#include <string.h>
+#include <stdlib.h>
+
+int main(int argc, char** argv) {
+    if(argc < 2) {
+        fprintf(stdout, "Usage:\n  upkr [compress] [-0 .. -9] <file> [<out-file>]\n  upkr [uncompress] <file> [<out-file>]\n");
+        return 1;
+    }
+
+    int argi = 1;
+    int uncompress = 0;
+    int compression_level = 4;
+    if(strcmp(argv[argi], "compress") == 0) {
+        ++argi;
+    } else if(strcmp(argv[argi], "uncompress") == 0) {
+        uncompress = 1;
+        ++argi;
+    }
+
+    if(argi < argc && argv[argi][0] == '-') {
+        compression_level = atoi(argv[argi] + 1);
+        ++argi;
+    }
+
+    if(argi == argc) {
+        fprintf(stdout, "intput filename missing\n");
+        return 1;
+    }
+
+    const char* input_name = argv[argi++];
+    char* output_name;
+    if(argi < argc) {
+        output_name = argv[argi];
+    } else {
+        output_name = malloc(strlen(input_name) + 5);
+        strcpy(output_name, input_name);
+        strcat(output_name, uncompress ? ".unp" : ".upk");
+    }
+
+    FILE* file = fopen(input_name, "rb");
+    if(file == 0) {
+        fprintf(stdout, "failed to open input file '%s'\n", file);
+        return 1;
+    }
+    fseek(file, 0, SEEK_END);
+    long input_size = ftell(file);
+    rewind(file);
+
+    char* input_buffer = (char*)malloc(input_size);
+    long offset = 0;
+    while(offset < input_size) {
+        long read_size = fread(input_buffer + offset, 1, input_size - offset, file);
+        if(read_size <= 0) {
+            fprintf(stdout, "error reading input file\n");
+            return 1;
+        }
+        offset += read_size;
+    }
+    fclose(file);
+
+    long output_buffer_size = input_size * 8;
+    long output_size;
+    char* output_buffer = (char*)malloc(output_buffer_size);
+    for(;;) {
+        if(uncompress) {
+            output_size = upkr_uncompress(output_buffer, output_buffer_size, input_buffer, input_size);
+        } else {
+            output_size = upkr_compress(output_buffer, output_buffer_size, input_buffer, input_size, compression_level);
+        }
+        if(output_size < 0) {
+            return 1;
+        }
+        if(output_size <= output_buffer_size) {
+            break;
+        }
+        output_buffer = (char*)realloc(output_buffer, output_size);
+        output_buffer_size = output_size;
+    }
+
+    file = fopen(output_name, "wb");
+    if(file == 0) {
+        fprintf(stdout, "failed to open output file '%s'\n", output_name);
+        return 1;
+    }
+    offset = 0;
+    while(offset < output_size) {
+        long written_size = fwrite(output_buffer + offset, 1, output_size - offset, file);
+        if(written_size <= 0) {
+            fprintf(stdout, "error writing output file\n");
+            return 1;
+        }
+        offset += written_size;
+    }
+    fclose(file);
+
+    return 0;
+}