Reading a PCX file into memory
Hi,
I've been trying to create a PCX "object" with some handy members, using the following code (includes and unnecessary functions cut):-
Code:
typedef struct {
unsigned char manufacturer; /* = 10 */
unsigned char version;
unsigned char encoding;
unsigned char bitsperpixel;
int x;
int y;
int width;
int height;
} t_pcx_header;
typedef struct {
int width;
int height;
unsigned char *picdata;
} t_pic;
t_pic *load_pcx(char *filename)
{
FILE *fp;
t_pcx_header pcx;
t_pic *pic;
int databyte;
int count;
long l;
fp = fopen(filename, "rb");
if (fp == NULL)
{
printf("File error\n");
return NULL;
}
fread(&pcx, sizeof(pcx), 1, fp);
if (pcx.manufacturer != 10)
{
printf("Invalid manufacturer value %d\n", pcx.manufacturer);
return NULL;
}
else if (pcx.encoding != 1)
{
printf("Invalid encoding value %d\n", pcx.encoding);
return NULL;
}
else if (pcx.bitsperpixel != 8)
{
printf("Invalid bits per pixel value %d\n", pcx.bitsperpixel);
return NULL;
}
else if (pcx.x < 0 || pcx.x > 319 || pcx.y < 0 || pcx.y > 199 || pcx.width < 1 || pcx.width > 319 || pcx.height < 1 || pcx.height > 199)
{
printf("Invalid image dimensions x=%d, y=%d, width=%d, height=%d\n", pcx.x, pcx.y, pcx.width, pcx.height);
return NULL;
}
fseek(fp, 128, SEEK_SET);
pic = (t_pic *)malloc(sizeof(t_pic));
if (pic->picdata == NULL)
{
printf("Picture object: Memory allocation error\n");
return NULL;
}
pic->width = pcx.width + 1;
pic->height = pcx.height + 1;
pic->picdata = (unsigned char *)malloc((long)pic->width * pic->height);
if (pic->picdata == NULL)
{
printf("Picture data: Memory allocation error.\n");
return NULL;
}
for (l=0;l<(long)pic->width * pic->height;l++)
{
databyte = getc(fp);
if (databyte == EOF)
{
printf("Image read error\n");
return NULL;
}
if (databyte & 0xC0)
{
unsigned char j;
count = databyte & 0x3F;
databyte = getc(fp);
printf("%d\n", count);
for (j=0;j<count;j++)
pic->picdata[l++] = (unsigned char)databyte;
}
else
pic->picdata[l] = (unsigned char)databyte;
}
fclose(fp);
return pic;
}
I've tried compiling and running this using Borland Turbo C 2.0, but it keeps crashing (none of my amazing error checking being done :(), and I imagine it has something to do with the way I handle pointers. Any ideas?
