zint/backend/large.c

/* large.c - Handles binary manipulation of large numbers */

/*
    libzint - the open source barcode library
    Copyright (C) 2008 Robin Stuart <robin@zint.org.uk>

    This program is free software; you can redistribute it and/or modify
    it under the terms of the GNU General Public License as published by
    the Free Software Foundation; either version 3 of the License, or
    (at your option) any later version.

    This program is distributed in the hope that it will be useful,
    but WITHOUT ANY WARRANTY; without even the implied warranty of
    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
    GNU General Public License for more details.

    You should have received a copy of the GNU General Public License along
    with this program; if not, write to the Free Software Foundation, Inc.,
    51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
*/

#include <stdio.h>
#include <string.h>
#include "common.h"
#include "large.h"

static short int BCD[40] = {
	0, 0, 0, 0,
	1, 0, 0, 0,
	0, 1, 0, 0,
	1, 1, 0, 0,
	0, 0, 1, 0,
	1, 0, 1, 0,
	0, 1, 1, 0,
	1, 1, 1, 0,
	0, 0, 0, 1,
	1, 0, 0, 1 };

void binary_add(short int accumulator[], short int input_buffer[])
{ /* Binary addition */
	int i, carry, done;
	carry = 0;

	for(i = 0; i < 112; i++) {
		done = 0;
		if(((input_buffer[i] == 0) && (accumulator[i] == 0)) && ((carry == 0) && (done == 0))) {
			accumulator[i] = 0;
			carry = 0;
			done = 1;
		}
		if(((input_buffer[i] == 0) && (accumulator[i] == 0)) && ((carry == 1) && (done == 0))) {
			accumulator[i] = 1;
			carry = 0;
			done = 1;
		}
		if(((input_buffer[i] == 0) && (accumulator[i] == 1)) && ((carry == 0) && (done == 0))) {
			accumulator[i] = 1;
			carry = 0;
			done = 1;
		}
		if(((input_buffer[i] == 0) && (accumulator[i] == 1)) && ((carry == 1) && (done == 0))) {
			accumulator[i] = 0;
			carry = 1;
			done = 1;
		}
		if(((input_buffer[i] == 1) && (accumulator[i] == 0)) && ((carry == 0) && (done == 0))) {
			accumulator[i] = 1;
			carry = 0;
			done = 1;
		}
		if(((input_buffer[i] == 1) && (accumulator[i] == 0)) && ((carry == 1) && (done == 0))) {
			accumulator[i] = 0;
			carry = 1;
			done = 1;
		}
		if(((input_buffer[i] == 1) && (accumulator[i] == 1)) && ((carry == 0) && (done == 0))) {
			accumulator[i] = 0;
			carry = 1;
			done = 1;
		}
		if(((input_buffer[i] == 1) && (accumulator[i] == 1)) && ((carry == 1) && (done == 0))) {
			accumulator[i] = 1;
			carry = 1;
			done = 1;
		}
	}
}

void binary_subtract(short int accumulator[], short int input_buffer[])
{ 	/* 2's compliment subtraction */
	/* take input_buffer from accumulator and put answer in accumulator */
	int i;
	short int sub_buffer[112];
	
	for(i = 0; i < 112; i++) {
		if(input_buffer[i] == 0) {
			sub_buffer[i] = 1;
		} else {
			sub_buffer[i] = 0;
		}
	}
	binary_add(accumulator, sub_buffer);
	
	sub_buffer[0] = 1;
	
	for(i = 1; i < 112; i++) {
		sub_buffer[i] = 0;
	}
	binary_add(accumulator, sub_buffer);
}

void shiftdown(short int buffer[])
{
	int i;
	
	buffer[102] = 0;
	buffer[103] = 0;

	for(i = 0; i < 102; i++) {
		buffer[i] = buffer[i + 1];
	}
}

void shiftup(short int buffer[])
{
	int i;
	
	for(i = 102; i > 0; i--) {
		buffer[i] = buffer[i - 1];
	}
	
	buffer[0] = 0;
}

short int islarger(short int accum[], short int reg[])
{
	/* Returns 1 if accum[] is larger than reg[], else 0 */
	int i, latch, larger;
	latch = 0;
	i = 103;
	larger = 0;
	
	
	do {
		if((accum[i] == 1) && (reg[i] == 0)) {
			latch = 1;
			larger = 1;
		}
		if((accum[i] == 0) && (reg[i] == 1)) {
			latch = 1;
		}
		i--;
	} while ((latch == 0) && (i >= -1));
	
	return larger;
}

void binary_load(short int reg[], char data[], const unsigned int src_len)
{
	int read, i;
	short int temp[112] = { 0 };
	
	for(i = 0; i < 112; i++) {
		reg[i] = 0;
	}
	
	for(read = 0; read < src_len; read++) {

		for(i = 0; i < 112; i++) {
			temp[i] = reg[i];
		}
		
		for(i = 0; i < 9; i++) {
			binary_add(reg, temp);
		}
		
		temp[0] = BCD[ctoi(data[read]) * 4];
		temp[1] = BCD[(ctoi(data[read]) * 4) + 1];
		temp[2] = BCD[(ctoi(data[read]) * 4) + 2];
		temp[3] = BCD[(ctoi(data[read]) * 4) + 3];
		for(i = 4; i < 112; i++) {
			temp[i] = 0;
		}
		
		binary_add(reg, temp);
	}
}

void hex_dump(short int input_buffer[]) 
{
	int i, digit, byte_space;

	byte_space = 1;
	for(i = 100; i >= 0; i-=4) {
		digit = 0;
		digit += 1 * input_buffer[i];
		digit += 2 * input_buffer[i + 1];
		digit += 4 * input_buffer[i + 2];
		digit += 8 * input_buffer[i + 3];

		switch(digit) {
			case 0: printf("0"); break;
			case 1: printf("1"); break;
			case 2: printf("2"); break;
			case 3: printf("3"); break;
			case 4: printf("4"); break;
			case 5: printf("5"); break;
			case 6: printf("6"); break;
			case 7: printf("7"); break;
			case 8: printf("8"); break;
			case 9: printf("9"); break;
			case 10: printf("A"); break;
			case 11: printf("B"); break;
			case 12: printf("C"); break;
			case 13: printf("D"); break;
			case 14: printf("E"); break;
			case 15: printf("F"); break;
		}
		if(byte_space == 1) {
			byte_space = 0;
		} else {
			byte_space = 1;
			printf(" ");
		}
	}
	printf("\n");
}