bbmp_parser.c

#include <stdio.h>
#include <math.h>
#include <stdint.h>
#include <stdbool.h>
#include <stdlib.h>

#include "bbmp_parser.h"

/*  
 *  A header-only file composed of a few functions for parsing data and metadata from BMP4.0 files.
 *  Only supports the `BM` BITMAPINFOHEADER DIB structure.
*/

void bbmp_parse_bmp_metadata(unsigned char *raw_bmp_data, struct bbmp_Metadata *metadata) {
    /* 
        Reads BMP file metadata from the memory pointed to by raw_bmp_data. raw_bmp_data must be at least 54 (bound to change?) bytes wide. Saves all metadata in the structure pointed to by metadata.
        Returns true on success, false on failure. If memloc is < 54 bytes wide, behaviour is undefined
    */

    //--------- begin setting each property of the struct one by one
    metadata->header_iden[0] = *(raw_bmp_data + BSP_OFF_DIB_IDEN);
    metadata->header_iden[1] = *(raw_bmp_data + BSP_OFF_DIB_IDEN + 1);
    metadata->header_iden[2] = '\0';

    metadata->filesize = * (uint32_t*) (raw_bmp_data + BSP_OFF_FILESIZE);

    metadata->res1 = * (uint16_t *) (raw_bmp_data + BSP_OFF_RES1);
    metadata->res2 = * (uint16_t *) (raw_bmp_data + BSP_OFF_RES2);

    metadata->pixelarray_off = * (uint32_t *) (raw_bmp_data + BSP_OFF_PIXELARRAY_START);

    metadata->dib_size = * (uint32_t *) (raw_bmp_data + BSP_OFF_DIB_SIZE);

    metadata->pixelarray_width = * (int32_t *) (raw_bmp_data + BSP_OFF_DIB_IMGWIDTH);
    metadata->pixelarray_height = * (int32_t *) (raw_bmp_data + BSP_OFF_DIB_IMGHEIGHT);

    metadata->panes_num = * (uint16_t *) (raw_bmp_data + BSP_OFF_DIB_PLANESNUM);
    
    metadata->bpp = * (uint16_t *) (raw_bmp_data + BSP_OFF_DIB_BPP);

    metadata->compression_method = * (uint32_t *) (raw_bmp_data + BSP_OFF_DIB_COMPRESSION);

    metadata->pixelarray_size = * (uint32_t *) (raw_bmp_data + BSP_OFF_DIB_IMGSIZE);

    metadata->ppm_horiz = * (int32_t *) (raw_bmp_data + BSP_OFF_DIB_PPM_HORIZ);
    metadata->ppm_vert = * (int32_t *) (raw_bmp_data + BSP_OFF_DIB_PPM_VERT);

    metadata->colors_num = * (uint32_t *) (raw_bmp_data + BSP_OFF_DIB_COLORSNUM);
    metadata->colors_important_num = * (uint32_t *) (raw_bmp_data + BSP_OFF_DIB_IMPORTANTCOLORSNUM);
    
    //CUSTOM FIELDS (not in the spec or in the file, provided for ease of use)
    metadata->Bpp = metadata->bpp / 8;
    metadata->Bpr = ceil(( (double) metadata->bpp * metadata->pixelarray_width) / 32) * 4;
    metadata->Bpr_np = (metadata->pixelarray_width * metadata->Bpp);
    metadata->padding = metadata->Bpr - (metadata->pixelarray_width * metadata->Bpp);
    metadata->resolution = metadata->pixelarray_height * metadata->pixelarray_width;
    metadata->pixelarray_size_np = metadata->resolution * metadata->Bpp;
}

void bbmp_debug_bmp_metadata(const bbmp_Metadata *dbgtemp) {
    /* 
     * Prints all fields of the metadata storage struct to stdout. Useful for debugging
     * All printed in base 10.
    */

    //TODO: left justify the fields and prettify the output
    printf("bmpparser: header_iden -> %s\n", dbgtemp->header_iden); //is null terminated so %s works...
    printf("bmpparser: filesize -> %u\n", dbgtemp->filesize);
    printf("bmpparser: res1 -> %hu, res2 -> %hu\n", dbgtemp->res1, dbgtemp->res2);
    printf("bmpparser: pixelarray_off -> %u\n", dbgtemp->pixelarray_off);
    printf("bmpparser: dib_size -> %u\n", dbgtemp->dib_size);
    printf("bmpparser: pixelarray_width -> %d, pixelarray_height -> %d\n", dbgtemp->pixelarray_width, dbgtemp->pixelarray_height);
    printf("bmpparser: panes_num -> %hu\n", dbgtemp->panes_num);
    printf("bmpparser: bpp -> %hu\n", dbgtemp->bpp);
    printf("bmpparser: compression_method -> %u\n", dbgtemp->compression_method);
    printf("bmpparser: pixelarray_size -> %u\n", dbgtemp->pixelarray_size);
    printf("bmpparser: ppm_horiz -> %d, ppm_vert -> %d\n", dbgtemp->ppm_horiz, dbgtemp->ppm_vert);
    printf("bmpparser: colors_num -> %u, colors_important_num -> %u\n", dbgtemp->colors_num, dbgtemp->colors_important_num);
    
    //custom fields
    printf("bmpparser: Bpr -> %u\n", dbgtemp->Bpr);
    printf("bmpparser: Bpr_np -> %u\n", dbgtemp->Bpr_np);
    printf("bmpparser: Bpp -> %hu\n", dbgtemp->Bpp);
    printf("bmpparser: resolution -> %u\n", dbgtemp->resolution);
    printf("bmpparser: padding -> %u\n", dbgtemp->padding);
    printf("bmpparser: pixelarray_size_np -> %u\n", dbgtemp->pixelarray_size_np);
}