add main source file for decoder

Author: fsasm

decoder.c

@@ -0,0 +1,112 @@
+/*
+ * decoder.c
+ * @date 2016-02-03
+ * @author Fabjan Sukalia <[email protected]>
+ * @brief Tool to decode huffman encoded data in JPEG format
+ */
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <errno.h>
+#include <stdint.h>
+#include "bit_reader.h"
+#include "huff_dec.h"
+
+#define JPG_DHT		(0xC4)
+
+static const char *prog_name = "hufdec";
+
+void usage(void)
+{
+	fprintf(stderr, "USAGE: %s FILE_IN FILE_OUT\n", prog_name);
+	exit(EXIT_FAILURE);
+}
+
+
+void decode(FILE *in, FILE *out)
+{
+	uint8_t header[21];
+	if (fread(header, sizeof(header), 1, in) != 1) {
+		fprintf(stderr, "Couldn't read header\n");
+		exit(EXIT_FAILURE);
+	}
+
+	if (header[0] != 0xFF || header[1] != JPG_DHT) {
+		fprintf(stderr, "Invalid header\n");
+		exit(EXIT_FAILURE);
+	}
+
+	uint16_t header_length = (header[2] << 8) | header[3];
+	if (header_length < 19 || header_length > (19 + 256)) {
+		fprintf(stderr, "Invalid header length\n");
+		exit(EXIT_FAILURE);
+	}
+
+	/* table class and destination index - must be zero */
+	if (header[4] != 0) {
+		fprintf(stderr, "Invalid table class and destination index\n");
+		exit(EXIT_FAILURE);
+	}
+
+	uint16_t sum_symbol = 0;
+	for (int i = 0; i < 16; i++)
+		sum_symbol += header[5 + i];
+
+	if (sum_symbol == 0 || header_length == 19)
+		return; /* nothing to do */
+
+	uint8_t symbols[sum_symbol];
+	if (fread(symbols, sizeof(symbols), 1, in) != 1) {
+		fprintf(stderr, "Couldn't read symbol table\n");
+		exit(EXIT_FAILURE);
+	}
+
+	/* how many bytes for the output or how many symbols to read */
+	uint8_t tmp[sizeof(uint32_t)];
+	if (fread(tmp, sizeof(uint32_t), 1, in) != 1) {
+		fprintf(stderr, "Couldn't read number of data\n");
+		exit(EXIT_FAILURE);
+	}
+
+	uint32_t num_sym = (tmp[0] << 24) | (tmp[1] << 16) | (tmp[2] << 8) | tmp[3];
+
+	struct huff_dec *dec = huff_gen_dec(&header[5], symbols);
+	struct bit_reader *reader = bit_reader_create(in);
+
+	huff_decode_all(dec, reader, out, num_sym);
+
+	bit_reader_destroy(reader);
+	huff_destroy(dec);
+}
+
+int main(int argc, char *argv[])
+{
+	errno = 0;
+
+	if (argc > 1)
+		prog_name = argv[0];
+	
+	if (argc != 3)
+		usage();
+	
+	FILE *in = fopen(argv[1], "rb");
+	if (in == NULL) {
+		perror("Couldn't open input file");
+		return EXIT_FAILURE;
+	}
+
+	FILE *out = fopen(argv[2], "wb");
+	if (out == NULL) {
+		perror("Couldn't open output file");
+		return EXIT_FAILURE;
+	}
+
+	decode(in, out);
+
+
+	fclose(in);
+	fclose(out);
+
+	return 0;
+}
+