void mergeImages(unsigned char *inputBuffer1, unsigned char *inputBuffer2, int pbmHeight, int pbmWidth, int fSize) {
// Iteration and bit counters
int i;
int bitRemainder = ((pbmWidth % 8) != 0 ? 8 - (pbmWidth % 8) : 0);
int readBits = pbmHeight * (pbmWidth + bitRemainder) + 8;
unsigned char *outBuffer = malloc(readBits);
memset(outBuffer, 0, readBits);
for (i = 0; i < readBits; i++) {
if (getBitVal(inputBuffer1, i) == 1 && (getBitVal(inputBuffer2, i) == 0)) {
setBitVal(outBuffer, i);
}
else if (getBitVal(inputBuffer1, i) == 1 && (getBitVal(inputBuffer2, i) == 1)) {
setBitVal(outBuffer, i);
}
else if (getBitVal(inputBuffer1, i) == 0 && (getBitVal(inputBuffer2, i) == 1)) {
setBitVal(outBuffer, i);
}
}
fprintf(stdout, "P4\n");
fprintf(stdout, "%d %d", pbmWidth, pbmHeight);
for (i = 0; i < readBits / CHAR_BIT; i++) {
fprintf(stdout, "%c", outBuffer[i]);
}
}
int main(int argc, char* argv[])
{
int a = 0x03;
a= setBitVal(3, 5, a);
printf("%02x\n",a);
a = clearBitVal(0, 3, a);
printf("%02x\n",a);
a = 0x0f;
a = testIfSet(0,7,a);
printf("%02x\n",(unsigned)a);
a= 0x55;
a = toggleBits(0,7,a);
printf("%02x\n",(unsigned)a);
return 0;
}
void decryptPbm(unsigned char *inputBuffer, int pbmHeight, int pbmWidth, int bitRemainder) {
// Calculate new PBM output height / width / bit remainder
int newHeight = (pbmHeight / 2);
int newWidth = (pbmWidth / 2);
int newBitRemainder = ((newWidth % 8) != 0 ? 8 - (newWidth % 8) : 0);
int newTotalBits = newHeight * (newWidth + newBitRemainder); // Calculate number of bits to write in new image
unsigned char *outPbmImage = malloc(newTotalBits / CHAR_BIT);
memset(outPbmImage, 0, newTotalBits / CHAR_BIT);
// i is for inputBuffer
// l is for outPbmImage
// hitCount is for locating the end of the PBM image based on the newWidth, not pbmWidth since the input is double the width and i is used * 2
int i, hitCount = 0;
int l = 0;
int tLeft = 0;
int tRight = 0;
int bLeft = 0;
int bRight = 0;
// Iterate through inputBuffer until end of bits
// Since the new output image should be 1/4 the size, we will multiply by 4 here
for (i = 0, l = 0; i < (newTotalBits * 4); i++, l++) {
// Like the encrypt function, we need to account for the trailing bits at the end of the PBM image width
if (i != 0 && hitCount % newWidth == 0) {
// When we hit the newWidth, we need to go to the next block of bits, a 2x2 block becomes 1 bit in the output image
// Divide by 2 because we are hitting each block with i * 2
i += (pbmWidth + (bitRemainder * 2)) / 2;
// The output iterator needs to skip the trailing bits and go to the next row
l += newBitRemainder;
hitCount = 0;
}
// Assign bit values for eacch pixel block for comparison later
tLeft = getBitVal(inputBuffer, i * 2);
tRight = getBitVal(inputBuffer, (i * 2) + 1);
bLeft = getBitVal(inputBuffer, ((i * 2) + (pbmWidth + bitRemainder)));
bRight = getBitVal(inputBuffer, ((i * 2) + (pbmWidth + bitRemainder) + 1));
if (tLeft == 1 && tRight == 1 && bLeft == 1 && bRight == 1) {
setBitVal(outPbmImage, l);
}
hitCount++;
}
// Finally print outPbmImage to stdout
fprintf(stdout, "P4\n");
fprintf(stdout, "%d %d\n", newWidth, newHeight);
for (i = 0; i < (newTotalBits / CHAR_BIT); i++) {
fprintf(stdout, "%c", outPbmImage[i]);
}
// Clean up
free(outPbmImage);
free(inputBuffer);
}
