Pillow/src/libImaging/HexDecode.c

/*
 * The Python Imaging Library.
 * $Id$
 *
 * decoder for hex encoded image data
 *
 * history:
 * 96-05-16 fl Created
 *
 * Copyright (c) Fredrik Lundh 1996.
 * Copyright (c) Secret Labs AB 1997.
 *
 * See the README file for information on usage and redistribution.
 */

#include "Imaging.h"

#define HEX(v)                               \
    ((v >= '0' && v <= '9')   ? v - '0'      \
     : (v >= 'a' && v <= 'f') ? v - 'a' + 10 \
     : (v >= 'A' && v <= 'F') ? v - 'A' + 10 \
                              : -1)

int
ImagingHexDecode(Imaging im, ImagingCodecState state, UINT8 *buf, Py_ssize_t bytes) {
    UINT8 *ptr;
    int a, b;

    ptr = buf;

    for (;;) {
        if (bytes < 2) {
            return ptr - buf;
        }

        a = HEX(ptr[0]);
        b = HEX(ptr[1]);

        if (a < 0 || b < 0) {
            ptr++;
            bytes--;

        } else {
            ptr += 2;
            bytes -= 2;

            state->buffer[state->x] = (a << 4) + b;

            if (++state->x >= state->bytes) {
                /* Got a full line, unpack it */
                state->shuffle(
                    (UINT8 *)im->image[state->y], state->buffer, state->xsize
                );

                state->x = 0;

                if (++state->y >= state->ysize) {
                    /* End of file (errcode = 0) */
                    return -1;
                }
            }
        }
    }
}