main-c.cpp

算术编码c程序实现

// main-c.cpp - for compress

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include "bitio.h"
#include "errhand.h"
#include "main.h"

void usage_exit(char* prog_name);
void print_ratios(char* input, char* output);
long file_size(char* name);

int main( int argc, char* argv[] )
{
	BIT_FILE* output;
	FILE* input;

	setbuf(stdout, NULL);
	if (argc < 3)
		usage_exit(argv[0]);
	input = fopen(argv[1], "rb");
	if (input == NULL)
		fatal_error("Error opening %s for input\n", argv[1]);
	output = OpenOutputBitFile(argv[2]);
	if (output == NULL)
		fatal_error("Error opening %s for output\n", argv[2]);
	printf("\nCompressing %s to %s\n", argv[1], argv[2]);
	printf("Using %s\n", CompressionName);
	CompressFile(input, output, argc - 3, argv + 3);
	CloseOutputBitFile( output );
	fclose( input );
	print_ratios(argv[1], argv[2]);
	return 0;
}

void usage_exit(char* prog_name)
{
	char* short_name;
	char* extension;

	short_name = strrchr(prog_name, '\\');
	if (short_name == NULL)
		short_name = strrchr(prog_name, '/');
	if (short_name == NULL)
		short_name = strrchr(prog_name, ':');
	if (short_name != NULL)
		short_name++;
	else
		short_name = prog_name;
	extension = strrchr(short_name, '.');
	if (extension != NULL)
		*extension = '\0';
	printf("\nUsage: %s %s\n", short_name, Usage);
	exit(0);
}

#ifndef SEEK_END
#define SEEK_END 2
#endif

long file_size(char* name)
{
	long eof_ftell;
	FILE* file;
	file = fopen(name, "rb");
	if (file == NULL)
		return 0L;
	fseek(file, 0L, SEEK_END);
	eof_ftell = ftell(file);
	fclose(file);
	return eof_ftell;
}

void print_ratios(char* input, char* output)
{
	long input_size;
	long output_size;
	int ratio;

	input_size = file_size(input);
	if (input_size == 0)
		input_size = 1;
	output_size = file_size(output);	
	ratio = 100 - (int)(output_size * 100L / input_size);
	printf("\nInput bytes:       %ld\n", input_size);
	printf("Output bytes:      %ld\n", output_size);	
	printf("Compression ratio:   %d%%\n", ratio);
}