hexdump.c

#include <stdio.h>
#include <stdlib.h>
#include <string.h>

#define BLOCKSIZE 1024
#define OUTPUT_BUFFERS 8
#define WRITE_BUFFER_SIZE (2 * 16) + 4 + 8 + 1

/* generated with in python:
for i in range(0, 256):
	if i % 16 == 0:
		ret += ", \"%02x\"\n" %i
	else:
		ret += ", \"%02x\"" % i

*/

const char *lookupTable[256] = {
	  "00"
	, "01", "02", "03", "04", "05", "06", "07", "08", "09", "0a", "0b", "0c", "0d", "0e", "0f", "10"
	, "11", "12", "13", "14", "15", "16", "17", "18", "19", "1a", "1b", "1c", "1d", "1e", "1f", "20"
	, "21", "22", "23", "24", "25", "26", "27", "28", "29", "2a", "2b", "2c", "2d", "2e", "2f", "30"
	, "31", "32", "33", "34", "35", "36", "37", "38", "39", "3a", "3b", "3c", "3d", "3e", "3f", "40"
	, "41", "42", "43", "44", "45", "46", "47", "48", "49", "4a", "4b", "4c", "4d", "4e", "4f", "50"
	, "51", "52", "53", "54", "55", "56", "57", "58", "59", "5a", "5b", "5c", "5d", "5e", "5f", "60"
	, "61", "62", "63", "64", "65", "66", "67", "68", "69", "6a", "6b", "6c", "6d", "6e", "6f", "70"
	, "71", "72", "73", "74", "75", "76", "77", "78", "79", "7a", "7b", "7c", "7d", "7e", "7f", "80"
	, "81", "82", "83", "84", "85", "86", "87", "88", "89", "8a", "8b", "8c", "8d", "8e", "8f", "90"
	, "91", "92", "93", "94", "95", "96", "97", "98", "99", "9a", "9b", "9c", "9d", "9e", "9f", "a0"
	, "a1", "a2", "a3", "a4", "a5", "a6", "a7", "a8", "a9", "aa", "ab", "ac", "ad", "ae", "af", "b0"
	, "b1", "b2", "b3", "b4", "b5", "b6", "b7", "b8", "b9", "ba", "bb", "bc", "bd", "be", "bf", "c0"
	, "c1", "c2", "c3", "c4", "c5", "c6", "c7", "c8", "c9", "ca", "cb", "cc", "cd", "ce", "cf", "d0"
	, "d1", "d2", "d3", "d4", "d5", "d6", "d7", "d8", "d9", "da", "db", "dc", "dd", "de", "df", "e0"
	, "e1", "e2", "e3", "e4", "e5", "e6", "e7", "e8", "e9", "ea", "eb", "ec", "ed", "ee", "ef", "f0"
	, "f1", "f2", "f3", "f4", "f5", "f6", "f7", "f8", "f9", "fa", "fb", "fc", "fd", "fe", "ff"
};

#define SET(i, offset, bufferOffset, buff, writeBufferOffset) writeBuffer[writeBufferOffset + offset + 0] = lookupTable[buff[i + bufferOffset]][0]; writeBuffer[writeBufferOffset + offset + 1] = lookupTable[buff[i + bufferOffset]][1]

int main(int argc, const char *argv[]) {
	unsigned char buffer[BLOCKSIZE];
	unsigned char writeBuffer[WRITE_BUFFER_SIZE];
	unsigned char bufferedWriteBuffer[OUTPUT_BUFFERS][WRITE_BUFFER_SIZE];
	unsigned char fileSizeBuff[sizeof(int)];
	writeBuffer[WRITE_BUFFER_SIZE - 1] = '\n';
	for (int i = 8; i < WRITE_BUFFER_SIZE - 3; i += 9) {
		writeBuffer[i] = ' ';
	}
	FILE *fd = fopen(argv[1], "r");
	int charsRead = 0;
	int fileSize = 0;
	while ((charsRead = fread(buffer, sizeof(unsigned char), BLOCKSIZE, fd)) != 0) {
		for (int i = 0; i < charsRead;) {
			for (int x = 0; x < OUTPUT_BUFFERS; x++) {
				int fileSizeI = fileSize + i;
				memcpy(fileSizeBuff, &fileSizeI, sizeof(int));

				SET(0, 0, 3, fileSizeBuff, 0);
				SET(0, 2, 2, fileSizeBuff, 0);
				SET(0, 4, 1, fileSizeBuff, 0);
				SET(0, 6, 0, fileSizeBuff, 0);

				SET(i, 9, 0, buffer, 0);
				SET(i, 11, 1, buffer, 0);
				SET(i, 13, 2, buffer, 0);
				SET(i, 15, 3, buffer, 0);

				SET(i, 18, 4, buffer, 0);
				SET(i, 20, 5, buffer, 0);
				SET(i, 22, 6, buffer, 0);
				SET(i, 24, 7, buffer, 0);
				
				SET(i, 27, 8, buffer, 0);
				SET(i, 29, 9, buffer, 0);
				SET(i, 31, 10, buffer, 0);
				SET(i, 33, 11, buffer, 0);

				SET(i, 36, 12, buffer, 0);
				SET(i, 38, 13, buffer, 0);
				SET(i, 40, 14, buffer, 0);
				SET(i, 42, 15, buffer, 0);

				memcpy(bufferedWriteBuffer[x], writeBuffer, sizeof(writeBuffer));

				i += 16;
				if (i > charsRead) {
					break;
				}
			}
			fwrite(bufferedWriteBuffer, sizeof(char), sizeof(bufferedWriteBuffer), stdout);
		}
		fileSize += charsRead;
	}
	fclose(fd);
}