Pillow/src/libImaging/PcdDecode.c

/*
 * The Python Imaging Library.
 * $Id$
 *
 * decoder for uncompressed PCD image data.
 *
 * history:
 * 96-05-10 fl Created
 * 96-05-18 fl New tables
 * 97-01-25 fl Use PhotoYCC unpacker
 *
 * notes:
 * This driver supports uncompressed PCD modes only
 * (resolutions up to 768x512).
 *
 * Copyright (c) Fredrik Lundh 1996-97.
 * Copyright (c) Secret Labs AB 1997.
 *
 * See the README file for information on usage and redistribution.
 */

#include "Imaging.h"

int
ImagingPcdDecode(Imaging im, ImagingCodecState state, UINT8 *buf, Py_ssize_t bytes) {
    int x;
    int chunk;
    UINT8 *out;
    UINT8 *ptr;

    ptr = buf;

    chunk = 3 * state->xsize;

    for (;;) {
        /* We need data for two full lines before we can do anything */
        if (bytes < chunk) {
            return ptr - buf;
        }

        /* Unpack first line */
        out = state->buffer;
        for (x = 0; x < state->xsize; x++) {
            out[0] = ptr[x];
            out[1] = ptr[(x + 4 * state->xsize) / 2];
            out[2] = ptr[(x + 5 * state->xsize) / 2];
            out += 3;
        }

        state->shuffle((UINT8 *)im->image[state->y], state->buffer, state->xsize);

        if (++state->y >= state->ysize) {
            return -1; /* This can hardly happen */
        }

        /* Unpack second line */
        out = state->buffer;
        for (x = 0; x < state->xsize; x++) {
            out[0] = ptr[x + state->xsize];
            out[1] = ptr[(x + 4 * state->xsize) / 2];
            out[2] = ptr[(x + 5 * state->xsize) / 2];
            out += 3;
        }

        state->shuffle((UINT8 *)im->image[state->y], state->buffer, state->xsize);

        if (++state->y >= state->ysize) {
            return -1;
        }

        ptr += chunk;
        bytes -= chunk;
    }
}