Function Decode32

include/bmpread/bmpread.c:658–682

Decodes 32-bit bitmap data by applying bitmasks. The 16- and 32-bit * decoders could be made more efficient by whitelisting supported bit patterns * ahead of time and special-casing their decoding here, but this allows us to * support more bitmask patterns, and shouldn't be *too* inefficient in any * case. * * Takes a pointer to an output buffer scan line (p_out), a pointer to the end * of

 * scan line of file data (p_file), and our context.
 */
static void Decode32(uint8_t * p_out,
                     const uint8_t * p_out_end,
                     const uint8_t * p_file,
                     const read_context * p_ctx)
{
    const bitfield * bf = p_ctx->bitfields;

    while(p_out < p_out_end)
    {
        uint32_t value = LoadLittleUint32(p_file);

        *p_out++ = Make8Bits(ApplyBitfield(value, bf[0]), bf[0].span);
        *p_out++ = Make8Bits(ApplyBitfield(value, bf[1]), bf[1].span);
        *p_out++ = Make8Bits(ApplyBitfield(value, bf[2]), bf[2].span);
        if(p_ctx->out_channels == 4)
        {
            if(bf[3].span)
                *p_out++ = Make8Bits(ApplyBitfield(value, bf[3]), bf[3].span);
            else
                *p_out++ = BMPREAD_DEFAULT_ALPHA;
        }

        p_file += 4;
    }
}

/* Decodes 24-bit bitmap data--basically just swaps the order of color
 * components.