(SOLVED) fread() is driving me mad. please help

[georgian]

Hello guys,

something mad is happenning in line 79 of my code.

Code: [Select]

LINE 78: printf("%d\n", pixelX); //Prints 0
LINE 79: fread(romCH1, fileLen, 1, binary);
LINE 80: printf("%d\n", pixelX); //prints 170??? why?
The code is very very messy but that shouldn't be the problem....
 the variable pixelX (used to be pixel0) is initialized as uint8_t and it stays 0 until the fread() function is used. After that it suddenly becoms 170. I have no idea why and it sort of driving me mad. The code is under havy development and tests and also poor, sorry if it makes your eyes bleed

Code: [Select]

/*
    https://stackoverflow.com/questions/12378642/c-pixels-in-console-window
*/

#include <stdint.h>
#include <stdio.h>
#include <windows.h>
#include <math.h>

#define romSize     0x7fff          //27C256

uint8_t ch2 = 0b01101001;   //0x69
uint8_t ch1 = 0b10011111;   //0x9F

uint8_t romCH1[romSize];    //Lower Byte
uint8_t romCH2[romSize];    //Upper Byte
uint16_t buffer[romSize];   //Lower and Upper combined.

uint8_t var, pixelX, pixel1, pixel2, pixel3 = 0;
//uint8_t var;

uint8_t px[4];

#define PI 3.14

uint32_t fileLen;
FILE *binary;

COLORREF palette[16] = {
    RGB(0x00, 0x00, 0x00),  //Black         #0
    RGB(0xDE, 0xEB, 0xB8),  //Cream         #1
    RGB(0xFF, 0xA0, 0x97),  //Pink          #2
    RGB(0xFF, 0xA0, 0x97),  //Pink          #3
    RGB(0xFF, 0x00, 0x00),  //Red           #4
    RGB(0x00, 0x00, 0x00),  //Black         #5
    RGB(0x00, 0xA0, 0x00),  //Dark Green    #6
    RGB(0x00, 0x00, 0xDE),  //Some Blue     #7
    RGB(0x47, 0xEB, 0x47),  //Light Green   #8
    RGB(0x00, 0xEB, 0xFF),  //Sky Blue      #9
    RGB(0xFF, 0xEB, 0xFF),  //Dirty White   #A
    RGB(0xFF, 0x00, 0x00),  //Red           #B
    RGB(0x47, 0x4B, 0x47),  //Gray          #C
    RGB(0x47, 0xEB, 0x97),  //Unseen Green  #D
    RGB(0x00, 0x00, 0x00),  //Black         #E
    RGB(0x00, 0x00, 0x00),  //Black         #F
};

uint8_t getPixelColor(uint32_t adress, uint8_t pixelPos, uint8_t lowByte, uint8_t highByte);

int main()
{


    pixel1 = ((ch2 >> 5) & 1) << 3;
    pixel1 |= ((ch2 >> 1) & 1) << 2;
    pixel1 |= ((ch1 >> 5) & 1) << 1;
    pixel1 |= ((ch1 >> 1) & 1);

    pixel2  = ((ch2 >> 6) & 1) << 3;
    pixel2 |= ((ch2 >> 2) & 1) << 2;
    pixel2 |= ((ch1 >> 6) & 1) << 1;
    pixel2 |= ((ch1 >> 2) & 1);

    pixel3  = ((ch2 >> 7) & 1) << 3;
    pixel3 |= ((ch2 >> 3) & 1) << 2;
    pixel3 |= ((ch1 >> 7) & 1) << 1;
    pixel3 |= ((ch1 >> 3) & 1);



    binary = fopen("jolycard.ch1", "rb");
    //if (!binary) { printf("ERROR!\n");}
    fseek(binary, 0, SEEK_END);
    fileLen = ftell(binary);

    rewind(binary);

    printf("%d\n", pixelX); //Prints 0
    fread(romCH1, fileLen, 1, binary);
    printf("%d\n", pixelX); //prints 170??? why?

    fclose(binary);

    binary = fopen("jolycard.ch2", "rb");
    if (!binary) {
            printf("ERROR!\n");
            system("cls");
    }
    fseek(binary, 0, SEEK_END);
    fileLen = ftell(binary);
    rewind(binary);
    fread(romCH2, fileLen, 1, binary);
    fclose(binary);

    //printf("\n\nBuffer:%X\n", romCH2[romSize]);

//    for (uint32_t p = 0; p <= romSize; p++) {
//        buffer[p] = (romCH2[p] << 8) | romCH1[p];
//        //printf("%X ", romCH1[p]);
//        //if (p%4 == 0)
//          //  printf("\n");
//    }
    //printf("\n\nBuffer:%X\n", buffer[romSize]);

    printf("CH1:0x%X CH2:0x%X\nPixel[0] HEX:0x%X DEC:%d\n\n", ch1, ch2, pixelX, pixelX);
    printf("CH1:0x%X CH2:0x%X\nPixel[1] HEX:0x%X DEC:%d\n\n", ch1, ch2, pixel1, pixel1);
    printf("CH1:0x%X CH2:0x%X\nPixel[2] HEX:0x%X DEC:%d\n\n", ch1, ch2, pixel2, pixel2);
    printf("CH1:0x%X CH2:0x%X\nPixel[3] HEX:0x%X DEC:%d\n\n", ch1, ch2, pixel3, pixel3);

    uint8_t pp = getPixelColor(0, 0, romCH1[0], romCH2[0]);

    printf("Pixel:%X\n", pp);

    //Get a console handle
    HWND myconsole = GetConsoleWindow();
    //Get a handle to device context
    HDC mydc = GetDC(myconsole);

    int pixel =0;

    //Choose any color
    COLORREF COLOR= RGB(0,255,0);

    //Draw pixels
    for(double i = 0; i < PI * 4; i += 0.05)
    {
        SetPixel(mydc,pixel,(int)(50+25*cos(i)),palette[0x9]);
        pixel+=1;
    }

    ReleaseDC(myconsole, mydc);

    return 0;
}

uint8_t getPixelColor(uint32_t adress, uint8_t pixelPos, uint8_t lowByte, uint8_t highByte) {
//    pixel0 = (((ch2 >> 4) & 1) << 3) | ((ch2 & 1) << 2) | (((ch1 >> 4) & 1) << 1) | (((ch1 >> 4) & 1) << 1) | (ch1 & 1);
//
//    pixel1 = (((ch2 >> 5) & 1) << 3) | (((ch2 >> 1) & 1) << 2) | (((ch1 >> 5) & 1) << 1) | ((ch1 >> 1) & 1);
//
//
//    pixel2 = (((ch2 >> 6) & 1) << 3) | (((ch2 >> 2) & 1) << 2) | (((ch1 >> 6) & 1) << 1) | ((ch1 >> 2) & 1);
//    pixel2 |= ((ch2 >> 2) & 1) << 2;
//    pixel2 |= ((ch1 >> 6) & 1) << 1;
//    pixel2 |= ((ch1 >> 2) & 1);
//
//    pixel3  = (((ch2 >> 7) & 1) << 3) | (((ch2 >> 3) & 1) << 2) | (((ch1 >> 7) & 1) << 1) | ((ch1 >> 3) & 1);
//    pixel3 |= ((ch2 >> 3) & 1) << 2;
//    pixel3 |= ((ch1 >> 7) & 1) << 1;
//    pixel3 |= ((ch1 >> 3) & 1);

    switch(pixelPos) {
        case 0:{
            return (((highByte >> 4) & 1) << 3) | ((highByte & 1) << 2) | (((lowByte >> 4) & 1) << 1) | (lowByte & 1);
            break;
        }
        case 1: {
            return (((highByte >> 5) & 1) << 3) | (((highByte >> 1) & 1) << 2) | (((lowByte >> 5) & 1) << 1) | (((lowByte >> 1) & 1));
            break;
        }
        case 2: {
            return (((highByte >> 6) & 1) << 3) | (((highByte >> 2) & 1) << 2) | (((lowByte >> 6) & 1) << 1) | ((lowByte >> 2) & 1);
            break;
        }
        case 3: {
            return (((highByte >> 7) & 1) << 3) | (((highByte >> 3) & 1) << 2) | (((lowByte >> 7) & 1) << 1) | ((lowByte >> 3) & 1);
            break;
        }

        default: {

            return 0xFF;
            break;
        }
    }


    return 0;
}



[langwadt]

how long is the file?

[georgian]

how long is the file?

27C256 eprom dump
fileLen prints as 32768

[georgian]

Thank you @langwadt!
I found the bug, array was to small.  Changed the array size and pixelX stays at 0. I forgot abaout the leading \0 in an array... What a relieve.

Thanks for pointing that out.

Code: [Select]

#define romSize     (0x7fff + 1)          //27C256

[magic]

You may want to add a check for this after reading the file size.

Sooner or later you will run this code on a different (larger) file and again.

[DavidAlfa]

This is PC, so just get the file size and allocate the buffer dynamically.

Code: [Select]

uint8_t * buf = NULL;
fileLen = ftell(binary);
buf = malloc(fileLen );
if(!buf){
  printf("Unable to allocate file buffer!\r\n");
  error();
}

Just remember to free the buffer when you're done with it:

Code: [Select]

free(buf);

Same for the other buffers.

[georgian]

This is PC, so just get the file size and allocate the buffer dynamically.

Code: [Select]

uint8_t * buf = NULL;
fileLen = ftell(binary);
buf = malloc(fileLen );
if(!buf){
  printf("Unable to allocate file buffer!\r\n");
  error();
}

Just remember to free the buffer when you're done with it:

Code: [Select]

free(buf);

Same for the other buffers.

The buffer should be globaly so I can access it from other functions.

[DavidAlfa]

It will be accesibe by anything if you declare a global pointer.
You can do the malloc anywhere, the pointer and the data will be valid until you free it up.
Just always check the buffer is valid (Not NULL) before accessing it.

Code: [Select]

uint8_t buf;

int allocate_buffer(void){
  (...)
  fileLen = ftell(binary);
  buf=malloc(fileLen); 
  return(buf==NULL);           // Always check for valid pointer. If NULL, buffer allocation failed, return 1.
}

int process_buffer(void){
  if(buf==NULL)                 // It won't harm to check again the pointer is valid. As the program grows, new bugs are introduced, this might save your a$$ :)
    return 1;
  ( do whatever with buffer )
  free(buf);  //Done
  buf=NULL;  // Good practice to clear the pointer after freeing it up.
}

int main(void){
  if(allocate_buffer())
    error();
  else
    process_buffer();
}