/*
 * The Python Imaging Library.
 * $Id$
 *
 * code to unpack raw data from various file formats
 *
 * history:
 * 1996-03-07 fl   Created (from various decoders)
 * 1996-04-19 fl   Added band unpackers
 * 1996-05-12 fl   Published RGB unpackers
 * 1996-05-27 fl   Added nibble unpacker
 * 1996-12-10 fl   Added complete set of PNG unpackers
 * 1996-12-29 fl   Set alpha byte in RGB unpackers
 * 1997-01-05 fl   Added remaining TGA unpackers
 * 1997-01-18 fl   Added inverting band unpackers
 * 1997-01-25 fl   Added FlashPix unpackers
 * 1997-05-31 fl   Added floating point unpackers
 * 1998-02-08 fl   Added I unpacker
 * 1998-07-01 fl   Added YCbCr unpacker
 * 1998-07-02 fl   Added full set of integer unpackers
 * 1998-12-29 fl   Added mode field, I;16 unpackers
 * 1998-12-30 fl   Added RGBX modes
 * 1999-02-04 fl   Fixed I;16 unpackers
 * 2003-05-13 fl   Added L/RGB reversed unpackers
 * 2003-09-26 fl   Added LA/PA and RGBa->RGB unpackers
 *
 * Copyright (c) 1997-2003 by Secret Labs AB.
 * Copyright (c) 1996-1997 by Fredrik Lundh.
 *
 * See the README file for information on usage and redistribution.
 */

#include "Imaging.h"


#define R 0
#define G 1
#define B 2
#define X 3

#define A 3

#define C 0
#define M 1
#define Y 2
#define K 3

#define CLIP(x) ((x) <= 0 ? 0 : (x) < 256 ? (x) : 255)

/* byte-swapping macros */

#define C16N\
        (tmp[0]=in[0], tmp[1]=in[1]);
#define C16S\
        (tmp[1]=in[0], tmp[0]=in[1]);
#define C32N\
        (tmp[0]=in[0], tmp[1]=in[1], tmp[2]=in[2], tmp[3]=in[3]);
#define C32S\
        (tmp[3]=in[0], tmp[2]=in[1], tmp[1]=in[2], tmp[0]=in[3]);
#define C64N\
        (tmp[0]=in[0], tmp[1]=in[1], tmp[2]=in[2], tmp[3]=in[3],\
         tmp[4]=in[4], tmp[5]=in[5], tmp[6]=in[6], tmp[7]=in[7]);
#define C64S\
        (tmp[7]=in[0], tmp[6]=in[1], tmp[5]=in[2], tmp[4]=in[3],\
         tmp[3]=in[4], tmp[2]=in[5], tmp[1]=in[6], tmp[0]=in[7]);

#ifdef WORDS_BIGENDIAN
#define C16B C16N
#define C16L C16S
#define C32B C32N
#define C32L C32S
#define C64B C64N
#define C64L C64S
#else
#define C16B C16S
#define C16L C16N
#define C32B C32S
#define C32L C32N
#define C64B C64S
#define C64L C64N
#endif

/* bit-swapping */

static UINT8 BITFLIP[] = {
    0, 128, 64, 192, 32, 160, 96, 224, 16, 144, 80, 208, 48, 176, 112,
    240, 8, 136, 72, 200, 40, 168, 104, 232, 24, 152, 88, 216, 56, 184,
    120, 248, 4, 132, 68, 196, 36, 164, 100, 228, 20, 148, 84, 212, 52,
    180, 116, 244, 12, 140, 76, 204, 44, 172, 108, 236, 28, 156, 92, 220,
    60, 188, 124, 252, 2, 130, 66, 194, 34, 162, 98, 226, 18, 146, 82,
    210, 50, 178, 114, 242, 10, 138, 74, 202, 42, 170, 106, 234, 26, 154,
    90, 218, 58, 186, 122, 250, 6, 134, 70, 198, 38, 166, 102, 230, 22,
    150, 86, 214, 54, 182, 118, 246, 14, 142, 78, 206, 46, 174, 110, 238,
    30, 158, 94, 222, 62, 190, 126, 254, 1, 129, 65, 193, 33, 161, 97,
    225, 17, 145, 81, 209, 49, 177, 113, 241, 9, 137, 73, 201, 41, 169,
    105, 233, 25, 153, 89, 217, 57, 185, 121, 249, 5, 133, 69, 197, 37,
    165, 101, 229, 21, 149, 85, 213, 53, 181, 117, 245, 13, 141, 77, 205,
    45, 173, 109, 237, 29, 157, 93, 221, 61, 189, 125, 253, 3, 131, 67,
    195, 35, 163, 99, 227, 19, 147, 83, 211, 51, 179, 115, 243, 11, 139,
    75, 203, 43, 171, 107, 235, 27, 155, 91, 219, 59, 187, 123, 251, 7,
    135, 71, 199, 39, 167, 103, 231, 23, 151, 87, 215, 55, 183, 119, 247,
    15, 143, 79, 207, 47, 175, 111, 239, 31, 159, 95, 223, 63, 191, 127,
    255
};

/* Unpack to "1" image */

static void
unpack1(UINT8* out, const UINT8* in, int pixels)
{
    /* bits (msb first, white is non-zero) */
    while (pixels > 0) {
        UINT8 byte = *in++;
        switch (pixels) {
        default:    *out++ = (byte & 128) ? 255 : 0; byte <<= 1;
        case 7:     *out++ = (byte & 128) ? 255 : 0; byte <<= 1;
        case 6:     *out++ = (byte & 128) ? 255 : 0; byte <<= 1;
        case 5:     *out++ = (byte & 128) ? 255 : 0; byte <<= 1;
        case 4:     *out++ = (byte & 128) ? 255 : 0; byte <<= 1;
        case 3:     *out++ = (byte & 128) ? 255 : 0; byte <<= 1;
        case 2:     *out++ = (byte & 128) ? 255 : 0; byte <<= 1;
        case 1:     *out++ = (byte & 128) ? 255 : 0;
        }
        pixels -= 8;
    }
}

static void
unpack1I(UINT8* out, const UINT8* in, int pixels)
{
    /* bits (msb first, white is zero) */
    while (pixels > 0) {
        UINT8 byte = *in++;
        switch (pixels) {
        default:    *out++ = (byte & 128) ? 0 : 255; byte <<= 1;
        case 7:     *out++ = (byte & 128) ? 0 : 255; byte <<= 1;
        case 6:     *out++ = (byte & 128) ? 0 : 255; byte <<= 1;
        case 5:     *out++ = (byte & 128) ? 0 : 255; byte <<= 1;
        case 4:     *out++ = (byte & 128) ? 0 : 255; byte <<= 1;
        case 3:     *out++ = (byte & 128) ? 0 : 255; byte <<= 1;
        case 2:     *out++ = (byte & 128) ? 0 : 255; byte <<= 1;
        case 1:     *out++ = (byte & 128) ? 0 : 255;
        }
        pixels -= 8;
    }
}

static void
unpack1R(UINT8* out, const UINT8* in, int pixels)
{
    /* bits (lsb first, white is non-zero) */
    while (pixels > 0) {
        UINT8 byte = *in++;
        switch (pixels) {
        default:    *out++ = (byte & 1) ? 255 : 0; byte >>= 1;
        case 7:     *out++ = (byte & 1) ? 255 : 0; byte >>= 1;
        case 6:     *out++ = (byte & 1) ? 255 : 0; byte >>= 1;
        case 5:     *out++ = (byte & 1) ? 255 : 0; byte >>= 1;
        case 4:     *out++ = (byte & 1) ? 255 : 0; byte >>= 1;
        case 3:     *out++ = (byte & 1) ? 255 : 0; byte >>= 1;
        case 2:     *out++ = (byte & 1) ? 255 : 0; byte >>= 1;
        case 1:     *out++ = (byte & 1) ? 255 : 0;
        }
        pixels -= 8;
    }
}

static void
unpack1IR(UINT8* out, const UINT8* in, int pixels)
{
    /* bits (lsb first, white is zero) */
    while (pixels > 0) {
        UINT8 byte = *in++;
        switch (pixels) {
        default:    *out++ = (byte & 1) ? 0 : 255; byte >>= 1;
        case 7:     *out++ = (byte & 1) ? 0 : 255; byte >>= 1;
        case 6:     *out++ = (byte & 1) ? 0 : 255; byte >>= 1;
        case 5:     *out++ = (byte & 1) ? 0 : 255; byte >>= 1;
        case 4:     *out++ = (byte & 1) ? 0 : 255; byte >>= 1;
        case 3:     *out++ = (byte & 1) ? 0 : 255; byte >>= 1;
        case 2:     *out++ = (byte & 1) ? 0 : 255; byte >>= 1;
        case 1:     *out++ = (byte & 1) ? 0 : 255;
        }
        pixels -= 8;
    }
}


/* Unpack to "L" image */

static void
unpackL2(UINT8* out, const UINT8* in, int pixels)
{
    /* nibbles */
    while (pixels > 0) {
        UINT8 byte = *in++;
        switch (pixels) {
        default:    *out++ = ((byte >> 6) & 3) * 255 / 3; byte <<= 2;
        case 3:     *out++ = ((byte >> 6) & 3) * 255 / 3; byte <<= 2;
        case 2:     *out++ = ((byte >> 6) & 3) * 255 / 3; byte <<= 2;
        case 1:     *out++ = ((byte >> 6) & 3) * 255 / 3;
        }
        pixels -= 4;
    }
}

static void
unpackL4(UINT8* out, const UINT8* in, int pixels)
{
    /* nibbles */
    while (pixels > 0) {
        UINT8 byte = *in++;
        switch (pixels) {
        default:    *out++ = ((byte >> 4) & 15) * 255 / 15; byte <<= 4;
        case 1:     *out++ = ((byte >> 4) & 15) * 255 / 15;
        }
        pixels -= 2;
    }
}

static void
unpackLA(UINT8* out, const UINT8* in, int pixels)
{
    int i;
    /* LA, pixel interleaved */
    for (i = 0; i < pixels; i++) {
        out[R] = out[G] = out[B] = in[0];
        out[A] = in[1];
        in += 2; out += 4;
    }
}

static void
unpackLAL(UINT8* out, const UINT8* in, int pixels)
{
    int i;
    /* LA, line interleaved */
    for (i = 0; i < pixels; i++) {
        out[R] = out[G] = out[B] = in[i];
        out[A] = in[i+pixels];
        out += 4;
    }
}

static void
unpackLI(UINT8* out, const UINT8* in, int pixels)
{
    /* negative */
    int i;
    for (i = 0; i < pixels; i++)
        out[i] = ~in[i];
}

static void
unpackLR(UINT8* out, const UINT8* in, int pixels)
{
    int i;
    /* RGB, bit reversed */
    for (i = 0; i < pixels; i++) {
        out[i] = BITFLIP[in[i]];
    }
}

static void
unpackL16(UINT8* out, const UINT8* in, int pixels)
{
    /* int16 (upper byte, little endian) */
    int i;
    for (i = 0; i < pixels; i++) {
        out[i] = in[1];
        in += 2;
    }
}

static void
unpackL16B(UINT8* out, const UINT8* in, int pixels)
{
    int i;
    /* int16 (upper byte, big endian) */
    for (i = 0; i < pixels; i++) {
        out[i] = in[0];
        in += 2;
    }
}


/* Unpack to "P" image */

static void
unpackP1(UINT8* out, const UINT8* in, int pixels)
{
    /* bits */
    while (pixels > 0) {
        UINT8 byte = *in++;
        switch (pixels) {
        default:    *out++ = (byte >> 7) & 1; byte <<= 1;
        case 7:     *out++ = (byte >> 7) & 1; byte <<= 1;
        case 6:     *out++ = (byte >> 7) & 1; byte <<= 1;
        case 5:     *out++ = (byte >> 7) & 1; byte <<= 1;
        case 4:     *out++ = (byte >> 7) & 1; byte <<= 1;
        case 3:     *out++ = (byte >> 7) & 1; byte <<= 1;
        case 2:     *out++ = (byte >> 7) & 1; byte <<= 1;
        case 1:     *out++ = (byte >> 7) & 1;
        }
        pixels -= 8;
    }
}

static void
unpackP2(UINT8* out, const UINT8* in, int pixels)
{
    /* bit pairs */
    while (pixels > 0) {
        UINT8 byte = *in++;
        switch (pixels) {
        default:    *out++ = (byte >> 6) & 3; byte <<= 2;
        case 3:     *out++ = (byte >> 6) & 3; byte <<= 2;
        case 2:     *out++ = (byte >> 6) & 3; byte <<= 2;
        case 1:     *out++ = (byte >> 6) & 3;
        }
        pixels -= 4;
    }
}

static void
unpackP4(UINT8* out, const UINT8* in, int pixels)
{
    /* nibbles */
    while (pixels > 0) {
        UINT8 byte = *in++;
        switch (pixels) {
        default:    *out++ = (byte >> 4) & 15; byte <<= 4;
        case 1:     *out++ = (byte >> 4) & 15;
        }
        pixels -= 2;
    }
}

static void
unpackP2L(UINT8* out, const UINT8* in, int pixels)
{
    int i, j, m, s;
    /* bit layers */
    m = 128;
    s = (pixels+7)/8;
    for (i = j = 0; i < pixels; i++) {
        out[i] = ((in[j] & m) ? 1 : 0) + ((in[j + s] & m) ? 2 : 0);
        if ((m >>= 1) == 0) {
            m = 128;
            j++;
        }
    }
}

static void
unpackP4L(UINT8* out, const UINT8* in, int pixels)
{
    int i, j, m, s;
    /* bit layers (trust the optimizer ;-) */
    m = 128;
    s = (pixels+7)/8;
    for (i = j = 0; i < pixels; i++) {
        out[i] = ((in[j] & m) ? 1 : 0) + ((in[j + s] & m) ? 2 : 0) +
                 ((in[j + 2*s] & m) ? 4 : 0) + ((in[j + 3*s] & m) ? 8 : 0);
        if ((m >>= 1) == 0) {
            m = 128;
            j++;
        }
    }
}

/* Unpack to "RGB" image */

void
ImagingUnpackRGB(UINT8* out, const UINT8* in, int pixels)
{
    int i;
    /* RGB triplets */
    for (i = 0; i < pixels; i++) {
        out[R] = in[0];
        out[G] = in[1];
        out[B] = in[2];
        out[A] = 255;
        out += 4; in += 3;
    }
}

void
unpackRGB16B(UINT8* out, const UINT8* in, int pixels)
{
    int i;
    /* 16-bit RGB triplets, big-endian order */
    for (i = 0; i < pixels; i++) {
        out[R] = in[0];
        out[G] = in[2];
        out[B] = in[4];
        out[A] = 255;
        out += 4; in += 6;
    }
}

static void
unpackRGBL(UINT8* out, const UINT8* in, int pixels)
{
    int i;
    /* RGB, line interleaved */
    for (i = 0; i < pixels; i++) {
        out[R] = in[i];
        out[G] = in[i+pixels];
        out[B] = in[i+pixels+pixels];
        out[A] = 255;
        out += 4;
    }
}

static void
unpackRGBR(UINT8* out, const UINT8* in, int pixels)
{
    int i;
    /* RGB, bit reversed */
    for (i = 0; i < pixels; i++) {
        out[R] = BITFLIP[in[0]];
        out[G] = BITFLIP[in[1]];
        out[B] = BITFLIP[in[2]];
        out[A] = 255;
        out += 4; in += 3;
    }
}

void
ImagingUnpackBGR(UINT8* out, const UINT8* in, int pixels)
{
    int i;
    /* RGB, reversed bytes */
    for (i = 0; i < pixels; i++) {
        out[R] = in[2];
        out[G] = in[1];
        out[B] = in[0];
        out[A] = 255;
        out += 4; in += 3;
    }
}

void
ImagingUnpackRGB15(UINT8* out, const UINT8* in, int pixels)
{
    int i, pixel;
    /* RGB, 5 bits per pixel */
    for (i = 0; i < pixels; i++) {
        pixel = in[0] + (in[1] << 8);
        out[R] = (pixel & 31) * 255 / 31;
        out[G] = ((pixel>>5) & 31) * 255 / 31;
        out[B] = ((pixel>>10) & 31) * 255 / 31;
        out[A] = 255;
        out += 4; in += 2;
    }
}

void
ImagingUnpackRGBA15(UINT8* out, const UINT8* in, int pixels)
{
    int i, pixel;
    /* RGB, 5/5/5/1 bits per pixel */
    for (i = 0; i < pixels; i++) {
        pixel = in[0] + (in[1] << 8);
        out[R] = (pixel & 31) * 255 / 31;
        out[G] = ((pixel>>5) & 31) * 255 / 31;
        out[B] = ((pixel>>10) & 31) * 255 / 31;
        out[A] = (pixel>>15) * 255;
        out += 4; in += 2;
    }
}

void
ImagingUnpackBGR15(UINT8* out, const UINT8* in, int pixels)
{
    int i, pixel;
    /* RGB, reversed bytes, 5 bits per pixel */
    for (i = 0; i < pixels; i++) {
        pixel = in[0] + (in[1] << 8);
        out[B] = (pixel & 31) * 255 / 31;
        out[G] = ((pixel>>5) & 31) * 255 / 31;
        out[R] = ((pixel>>10) & 31) * 255 / 31;
        out[A] = 255;
        out += 4; in += 2;
    }
}

void
ImagingUnpackBGRA15(UINT8* out, const UINT8* in, int pixels)
{
    int i, pixel;
    /* RGB, reversed bytes, 5/5/5/1 bits per pixel */
    for (i = 0; i < pixels; i++) {
        pixel = in[0] + (in[1] << 8);
        out[B] = (pixel & 31) * 255 / 31;
        out[G] = ((pixel>>5) & 31) * 255 / 31;
        out[R] = ((pixel>>10) & 31) * 255 / 31;
        out[A] = (pixel>>15) * 255;
        out += 4; in += 2;
    }
}

void
ImagingUnpackRGB16(UINT8* out, const UINT8* in, int pixels)
{
    int i, pixel;
    /* RGB, 5/6/5 bits per pixel */
    for (i = 0; i < pixels; i++) {
        pixel = in[0] + (in[1] << 8);
        out[R] = (pixel & 31) * 255 / 31;
        out[G] = ((pixel>>5) & 63) * 255 / 63;
        out[B] = ((pixel>>11) & 31) * 255 / 31;
        out[A] = 255;
        out += 4; in += 2;
    }
}

void
ImagingUnpackBGR16(UINT8* out, const UINT8* in, int pixels)
{
    int i, pixel;
    /* RGB, reversed bytes, 5/6/5 bits per pixel */
    for (i = 0; i < pixels; i++) {
        pixel = in[0] + (in[1] << 8);
        out[B] = (pixel & 31) * 255 / 31;
        out[G] = ((pixel>>5) & 63) * 255 / 63;
        out[R] = ((pixel>>11) & 31) * 255 / 31;
        out[A] = 255;
        out += 4; in += 2;
    }
}

void
ImagingUnpackRGB4B(UINT8* out, const UINT8* in, int pixels)
{
    int i, pixel;
    /* RGB, 4 bits per pixel */
    for (i = 0; i < pixels; i++) {
        pixel = in[0] + (in[1] << 8);
        out[R] = (pixel & 15) * 17;
        out[G] = ((pixel>>4) & 15) * 17;
        out[B] = ((pixel>>8) & 15) * 17;
        out[A] = 255;
        out += 4; in += 2;
    }
}

void
ImagingUnpackRGBA4B(UINT8* out, const UINT8* in, int pixels)
{
    int i, pixel;
    /* RGBA, 4 bits per pixel */
    for (i = 0; i < pixels; i++) {
        pixel = in[0] + (in[1] << 8);
        out[R] = (pixel & 15) * 17;
        out[G] = ((pixel>>4) & 15) * 17;
        out[B] = ((pixel>>8) & 15) * 17;
        out[A] = ((pixel>>12) & 15) * 17;
        out += 4; in += 2;
    }
}

static void
ImagingUnpackBGRX(UINT8* out, const UINT8* in, int pixels)
{
    int i;
    /* RGB, reversed bytes with padding */
    for (i = 0; i < pixels; i++) {
        out[R] = in[2];
        out[G] = in[1];
        out[B] = in[0];
        out[A] = 255;
        out += 4; in += 4;
    }
}

static void
ImagingUnpackXRGB(UINT8* out, const UINT8* in, int pixels)
{
    int i;
    /* RGB, leading pad */
    for (i = 0; i < pixels; i++) {
        out[R] = in[1];
        out[G] = in[2];
        out[B] = in[3];
        out[A] = 255;
        out += 4; in += 4;
    }
}

static void
ImagingUnpackXBGR(UINT8* out, const UINT8* in, int pixels)
{
    int i;
    /* RGB, reversed bytes, leading pad */
    for (i = 0; i < pixels; i++) {
        out[R] = in[3];
        out[G] = in[2];
        out[B] = in[1];
        out[A] = 255;
        out += 4; in += 4;
    }
}

/* Unpack to "RGBA" image */

static void
unpackRGBALA(UINT8* out, const UINT8* in, int pixels)
{
    int i;
    /* greyscale with alpha */
    for (i = 0; i < pixels; i++) {
        out[R] = out[G] = out[B] = in[0];
        out[A] = in[1];
        out += 4; in += 2;
    }
}

static void
unpackRGBALA16B(UINT8* out, const UINT8* in, int pixels)
{
    int i;
    /* 16-bit greyscale with alpha, big-endian */
    for (i = 0; i < pixels; i++) {
        out[R] = out[G] = out[B] = in[0];
        out[A] = in[2];
        out += 4; in += 4;
    }
}

static void
unpackRGBa(UINT8* out, const UINT8* in, int pixels)
{
    int i;
    /* premultiplied RGBA */
    for (i = 0; i < pixels; i++) {
        int a = in[3];
        if (!a)
            out[R] = out[G] = out[B] = out[A] = 0;
        else {
            out[R] = CLIP(in[0] * 255 / a);
            out[G] = CLIP(in[1] * 255 / a);
            out[B] = CLIP(in[2] * 255 / a);
            out[A] = a;
        }
        out += 4; in += 4;
    }
}

static void
unpackRGBAI(UINT8* out, const UINT8* in, int pixels)
{
    int i;
    /* RGBA, inverted RGB bytes (FlashPix) */
    for (i = 0; i < pixels; i++) {
        out[R] = ~in[0];
        out[G] = ~in[1];
        out[B] = ~in[2];
        out[A] = in[3];
        out += 4; in += 4;
    }
}

static void
unpackRGBAL(UINT8* out, const UINT8* in, int pixels)
{
    int i;

    /* RGBA, line interleaved */
    for (i = 0; i < pixels; i++) {
        out[R] = in[i];
        out[G] = in[i+pixels];
        out[B] = in[i+pixels+pixels];
        out[A] = in[i+pixels+pixels+pixels];
        out += 4;
    }
}

void
unpackRGBA16B(UINT8* out, const UINT8* in, int pixels)
{
    int i;
    /* 16-bit RGBA, big-endian order */
    for (i = 0; i < pixels; i++) {
        out[R] = in[0];
        out[G] = in[2];
        out[B] = in[4];
        out[A] = in[6];
        out += 4; in += 8;
    }
}

static void
unpackARGB(UINT8* out, const UINT8* in, int pixels)
{
    int i;
    /* RGBA, leading pad */
    for (i = 0; i < pixels; i++) {
        out[R] = in[1];
        out[G] = in[2];
        out[B] = in[3];
        out[A] = in[0];
        out += 4; in += 4;
    }
}

static void
unpackABGR(UINT8* out, const UINT8* in, int pixels)
{
    int i;
    /* RGBA, reversed bytes */
    for (i = 0; i < pixels; i++) {
        out[R] = in[3];
        out[G] = in[2];
        out[B] = in[1];
        out[A] = in[0];
        out += 4; in += 4;
    }
}

static void
unpackBGRA(UINT8* out, const UINT8* in, int pixels)
{
    int i;
    /* RGBA, reversed bytes */
    for (i = 0; i < pixels; i++) {
        out[R] = in[2];
        out[G] = in[1];
        out[B] = in[0];
        out[A] = in[3];
        out += 4; in += 4;
    }
}


/* Unpack to "CMYK" image */

static void
unpackCMYKI(UINT8* out, const UINT8* in, int pixels)
{
    int i;
    /* CMYK, inverted bytes (Photoshop 2.5) */
    for (i = 0; i < pixels; i++) {
        out[C] = ~in[0];
        out[M] = ~in[1];
        out[Y] = ~in[2];
        out[K] = ~in[3];
        out += 4; in += 4;
    }
}

/* Unpack to "LAB" image */
/* There are two representations of LAB images for whatever precision:
   L: Uint (in PS, it's 0-100)
   A: Int (in ps, -128 .. 128, or elsewhere 0..255, with 128 as middle. 
           Channels in PS display a 0 value as middle grey, 
           LCMS appears to use 128 as the 0 value for these channels)
   B: Int (as above) 

   Since we don't have any signed ints, we're going with the shifted versions 
   internally, and we'll unshift for saving and whatnot. 
*/
void
ImagingUnpackLAB(UINT8* out, const UINT8* in, int pixels)
{
    int i;
    /* LAB triplets */
    for (i = 0; i < pixels; i++) {
        out[0] = in[0];
        out[1] = in[1] ^ 128; /* signed in outside world */
        out[2] = in[2] ^ 128;
        out[3] = 255;
        out += 4; in += 3;
    }
}

static void
copy1(UINT8* out, const UINT8* in, int pixels)
{
    /* L, P */
    memcpy(out, in, pixels);
}

static void
copy2(UINT8* out, const UINT8* in, int pixels)
{
    /* I;16 */
    memcpy(out, in, pixels*2);
}

static void
copy3(UINT8* out, const UINT8* in, int pixels)
{
    /* LAB triples, 24bit */
    memcpy(out, in, 3 * pixels);
}

static void
copy4(UINT8* out, const UINT8* in, int pixels)
{
    /* RGBA, CMYK quadruples */
    memcpy(out, in, 4 * pixels);
}


/* Unpack to "I" and "F" images */

#define UNPACK_RAW(NAME, GET, INTYPE, OUTTYPE)\
static void NAME(UINT8* out_, const UINT8* in, int pixels)\
{\
    int i;\
    OUTTYPE* out = (OUTTYPE*) out_;\
    for (i = 0; i < pixels; i++, in += sizeof(INTYPE))\
        out[i] = (OUTTYPE) ((INTYPE) GET);\
}

#define UNPACK(NAME, COPY, INTYPE, OUTTYPE)\
static void NAME(UINT8* out_, const UINT8* in, int pixels)\
{\
    int i;\
    OUTTYPE* out = (OUTTYPE*) out_;\
    INTYPE tmp_;\
    UINT8* tmp = (UINT8*) &tmp_;\
    for (i = 0; i < pixels; i++, in += sizeof(INTYPE)) {\
        COPY;\
        out[i] = (OUTTYPE) tmp_;\
    }\
}

UNPACK_RAW(unpackI8, in[0], UINT8, INT32)
UNPACK_RAW(unpackI8S, in[0], INT8, INT32)
UNPACK(unpackI16, C16L, UINT16, INT32)
UNPACK(unpackI16S, C16L, INT16, INT32)
UNPACK(unpackI16B, C16B, UINT16, INT32)
UNPACK(unpackI16BS, C16B, INT16, INT32)
UNPACK(unpackI16N, C16N, UINT16, INT32)
UNPACK(unpackI16NS, C16N, INT16, INT32)
UNPACK(unpackI32, C32L, UINT32, INT32)
UNPACK(unpackI32S, C32L, INT32, INT32)
UNPACK(unpackI32B, C32B, UINT32, INT32)
UNPACK(unpackI32BS, C32B, INT32, INT32)
UNPACK(unpackI32N, C32N, UINT32, INT32)
UNPACK(unpackI32NS, C32N, INT32, INT32)

UNPACK_RAW(unpackF8, in[0], UINT8, FLOAT32)
UNPACK_RAW(unpackF8S, in[0], INT8, FLOAT32)
UNPACK(unpackF16, C16L, UINT16, FLOAT32)
UNPACK(unpackF16S, C16L, INT16, FLOAT32)
UNPACK(unpackF16B, C16B, UINT16, FLOAT32)
UNPACK(unpackF16BS, C16B, INT16, FLOAT32)
UNPACK(unpackF16N, C16N, UINT16, FLOAT32)
UNPACK(unpackF16NS, C16N, INT16, FLOAT32)
UNPACK(unpackF32, C32L, UINT32, FLOAT32)
UNPACK(unpackF32S, C32L, INT32, FLOAT32)
UNPACK(unpackF32B, C32B, UINT32, FLOAT32)
UNPACK(unpackF32BS, C32B, INT32, FLOAT32)
UNPACK(unpackF32N, C32N, UINT32, FLOAT32)
UNPACK(unpackF32NS, C32N, INT32, FLOAT32)
UNPACK(unpackF32F, C32L, FLOAT32, FLOAT32)
UNPACK(unpackF32BF, C32B, FLOAT32, FLOAT32)
UNPACK(unpackF32NF, C32N, FLOAT32, FLOAT32)
#ifdef FLOAT64
UNPACK(unpackF64F, C64L, FLOAT64, FLOAT32)
UNPACK(unpackF64BF, C64B, FLOAT64, FLOAT32)
UNPACK(unpackF64NF, C64N, FLOAT64, FLOAT32)
#endif


/* Misc. unpackers */

static void
band0(UINT8* out, const UINT8* in, int pixels)
{
    int i;
    /* band 0 only */
    for (i = 0; i < pixels; i++) {
        out[0] = in[i];
        out += 4;
    }
}

static void
band1(UINT8* out, const UINT8* in, int pixels)
{
    int i;
    /* band 1 only */
    for (i = 0; i < pixels; i++) {
        out[1] = in[i];
        out += 4;
    }
}

static void
band2(UINT8* out, const UINT8* in, int pixels)
{
    int i;
    /* band 2 only */
    for (i = 0; i < pixels; i++) {
        out[2] = in[i];
        out += 4;
    }
}

static void
band3(UINT8* out, const UINT8* in, int pixels)
{
    /* band 3 only */
    int i;
    for (i = 0; i < pixels; i++) {
        out[3] = in[i];
        out += 4;
    }
}

static void
band0I(UINT8* out, const UINT8* in, int pixels)
{
    int i;
    /* band 0 only */
    for (i = 0; i < pixels; i++) {
        out[0] = ~in[i];
        out += 4;
    }
}

static void
band1I(UINT8* out, const UINT8* in, int pixels)
{
    int i;
    /* band 1 only */
    for (i = 0; i < pixels; i++) {
        out[1] = ~in[i];
        out += 4;
    }
}

static void
band2I(UINT8* out, const UINT8* in, int pixels)
{
    int i;
    /* band 2 only */
    for (i = 0; i < pixels; i++) {
        out[2] = ~in[i];
        out += 4;
    }
}

static void
band3I(UINT8* out, const UINT8* in, int pixels)
{
    /* band 3 only */
    int i;
    for (i = 0; i < pixels; i++) {
        out[3] = ~in[i];
        out += 4;
    }
}

static struct {
    const char* mode;
    const char* rawmode;
    int bits;
    ImagingShuffler unpack;
} unpackers[] = {

    /* raw mode syntax is "<mode>;<bits><flags>" where "bits" defaults
       depending on mode (1 for "1", 8 for "P" and "L", etc), and
       "flags" should be given in alphabetical order.  if both bits
       and flags have their default values, the ; should be left out */

    /* flags: "I" inverted data; "R" reversed bit order; "B" big
       endian byte order (default is little endian); "L" line
       interleave, "S" signed, "F" floating point */

    /* bilevel */
    {"1",       "1",            1,      unpack1},
    {"1",       "1;I",          1,      unpack1I},
    {"1",       "1;R",          1,      unpack1R},
    {"1",       "1;IR",         1,      unpack1IR},

    /* greyscale */
    {"L",       "L;2",          2,      unpackL2},
    {"L",       "L;4",          4,      unpackL4},
    {"L",       "L",            8,      copy1},
    {"L",       "L;I",          8,      unpackLI},
    {"L",       "L;R",          8,      unpackLR},
    {"L",       "L;16",         16,     unpackL16},
    {"L",       "L;16B",        16,     unpackL16B},

    /* greyscale w. alpha */
    {"LA",      "LA",           16,     unpackLA},
    {"LA",      "LA;L",         16,     unpackLAL},

    /* palette */
    {"P",       "P;1",          1,      unpackP1},
    {"P",       "P;2",          2,      unpackP2},
    {"P",       "P;2L",         2,      unpackP2L},
    {"P",       "P;4",          4,      unpackP4},
    {"P",       "P;4L",         4,      unpackP4L},
    {"P",       "P",            8,      copy1},
    {"P",       "P;R",          8,      unpackLR},

    /* palette w. alpha */
    {"PA",      "PA",           16,     unpackLA},
    {"PA",      "PA;L",         16,     unpackLAL},

    /* true colour */
    {"RGB",     "RGB",          24,     ImagingUnpackRGB},
    {"RGB",     "RGB;L",        24,     unpackRGBL},
    {"RGB",     "RGB;R",        24,     unpackRGBR},
    {"RGB",     "RGB;16B",      48,     unpackRGB16B},
    {"RGB",     "BGR",          24,     ImagingUnpackBGR},
    {"RGB",     "RGB;15",       16,     ImagingUnpackRGB15},
    {"RGB",     "BGR;15",       16,     ImagingUnpackBGR15},
    {"RGB",     "RGB;16",       16,     ImagingUnpackRGB16},
    {"RGB",     "BGR;16",       16,     ImagingUnpackBGR16},
    {"RGB",     "RGB;4B",       16,     ImagingUnpackRGB4B},
    {"RGB",     "BGR;5",        16,     ImagingUnpackBGR15}, /* compat */
    {"RGB",     "RGBX",         32,     copy4},
    {"RGB",     "RGBX;L",       32,     unpackRGBAL},
    {"RGB",     "BGRX",         32,     ImagingUnpackBGRX},
    {"RGB",     "XRGB",         24,     ImagingUnpackXRGB},
    {"RGB",     "XBGR",         32,     ImagingUnpackXBGR},
    {"RGB",     "YCC;P",        24,     ImagingUnpackYCC},
    {"RGB",     "R",            8,      band0},
    {"RGB",     "G",            8,      band1},
    {"RGB",     "B",            8,      band2},

    /* true colour w. alpha */
    {"RGBA",    "LA",           16,     unpackRGBALA},
    {"RGBA",    "LA;16B",       32,     unpackRGBALA16B},
    {"RGBA",    "RGBA",         32,     copy4},
    {"RGBA",    "RGBa",         32,     unpackRGBa},
    {"RGBA",    "RGBA;I",       32,     unpackRGBAI},
    {"RGBA",    "RGBA;L",       32,     unpackRGBAL},
    {"RGBA",    "RGBA;15",      16,     ImagingUnpackRGBA15},
    {"RGBA",    "BGRA;15",      16,     ImagingUnpackBGRA15},
    {"RGBA",    "RGBA;4B",      16,     ImagingUnpackRGBA4B},
    {"RGBA",    "RGBA;16B",     64,     unpackRGBA16B},
    {"RGBA",    "BGRA",         32,     unpackBGRA},
    {"RGBA",    "ARGB",         32,     unpackARGB},
    {"RGBA",    "ABGR",         32,     unpackABGR},
    {"RGBA",    "YCCA;P",       32,     ImagingUnpackYCCA},
    {"RGBA",    "R",            8,      band0},
    {"RGBA",    "G",            8,      band1},
    {"RGBA",    "B",            8,      band2},
    {"RGBA",    "A",            8,      band3},

    /* true colour w. padding */
    {"RGBX",    "RGB",          24,     ImagingUnpackRGB},
    {"RGBX",    "RGB;L",        24,     unpackRGBL},
    {"RGBX",    "RGB;16B",      48,     unpackRGB16B},
    {"RGBX",    "BGR",          24,     ImagingUnpackBGR},
    {"RGBX",    "RGB;15",       16,     ImagingUnpackRGB15},
    {"RGBX",    "BGR;15",       16,     ImagingUnpackBGR15},
    {"RGBX",    "RGB;4B",       16,     ImagingUnpackRGB4B},
    {"RGBX",    "BGR;5",        16,     ImagingUnpackBGR15}, /* compat */
    {"RGBX",    "RGBX",         32,     copy4},
    {"RGBX",    "RGBX;L",       32,     unpackRGBAL},
    {"RGBX",    "BGRX",         32,     ImagingUnpackBGRX},
    {"RGBX",    "XRGB",         24,     ImagingUnpackXRGB},
    {"RGBX",    "XBGR",         32,     ImagingUnpackXBGR},
    {"RGBX",    "YCC;P",        24,     ImagingUnpackYCC},
    {"RGBX",    "R",            8,      band0},
    {"RGBX",    "G",            8,      band1},
    {"RGBX",    "B",            8,      band2},
    {"RGBX",    "X",            8,      band3},

    /* colour separation */
    {"CMYK",    "CMYK",         32,     copy4},
    {"CMYK",    "CMYK;I",       32,     unpackCMYKI},
    {"CMYK",    "CMYK;L",       32,     unpackRGBAL},
    {"CMYK",    "C",            8,      band0},
    {"CMYK",    "M",            8,      band1},
    {"CMYK",    "Y",            8,      band2},
    {"CMYK",    "K",            8,      band3},
    {"CMYK",    "C;I",          8,      band0I},
    {"CMYK",    "M;I",          8,      band1I},
    {"CMYK",    "Y;I",          8,      band2I},
    {"CMYK",    "K;I",          8,      band3I},

    /* video (YCbCr) */
    {"YCbCr",   "YCbCr",        24,     ImagingUnpackRGB},
    {"YCbCr",   "YCbCr;L",      24,     unpackRGBL},
    {"YCbCr",   "YCbCrX",       32,     copy4},
    {"YCbCr",   "YCbCrK",       32,     copy4},

    /* LAB Color */
    {"LAB",	    "LAB",	        24,	    ImagingUnpackLAB},
    {"LAB",  	"L",            8,      band0},
    {"LAB",  	"A",            8,      band1},
    {"LAB",  	"B",            8,      band2},

    /* integer variations */
    {"I",       "I",            32,     copy4},
    {"I",       "I;8",          8,      unpackI8},
    {"I",       "I;8S",         8,      unpackI8S},
    {"I",       "I;16",         16,     unpackI16},
    {"I",       "I;16S",        16,     unpackI16S},
    {"I",       "I;16B",        16,     unpackI16B},
    {"I",       "I;16BS",       16,     unpackI16BS},
    {"I",       "I;16N",        16,     unpackI16N},
    {"I",       "I;16NS",       16,     unpackI16NS},
    {"I",       "I;32",         32,     unpackI32},
    {"I",       "I;32S",        32,     unpackI32S},
    {"I",       "I;32B",        32,     unpackI32B},
    {"I",       "I;32BS",       32,     unpackI32BS},
    {"I",       "I;32N",        32,     unpackI32N},
    {"I",       "I;32NS",       32,     unpackI32NS},

    /* floating point variations */
    {"F",       "F",            32,     copy4},
    {"F",       "F;8",          8,      unpackF8},
    {"F",       "F;8S",         8,      unpackF8S},
    {"F",       "F;16",         16,     unpackF16},
    {"F",       "F;16S",        16,     unpackF16S},
    {"F",       "F;16B",        16,     unpackF16B},
    {"F",       "F;16BS",       16,     unpackF16BS},
    {"F",       "F;16N",        16,     unpackF16N},
    {"F",       "F;16NS",       16,     unpackF16NS},
    {"F",       "F;32",         32,     unpackF32},
    {"F",       "F;32S",        32,     unpackF32S},
    {"F",       "F;32B",        32,     unpackF32B},
    {"F",       "F;32BS",       32,     unpackF32BS},
    {"F",       "F;32N",        32,     unpackF32N},
    {"F",       "F;32NS",       32,     unpackF32NS},
    {"F",       "F;32F",        32,     unpackF32F},
    {"F",       "F;32BF",       32,     unpackF32BF},
    {"F",       "F;32NF",       32,     unpackF32NF},
#ifdef FLOAT64
    {"F",       "F;64F",        64,     unpackF64F},
    {"F",       "F;64BF",       64,     unpackF64BF},
    {"F",       "F;64NF",       64,     unpackF64NF},
#endif

    /* storage modes */
    {"I;16",    "I;16",         16,     copy2},
    {"I;16B",   "I;16B",        16,     copy2},
    {"I;16L",   "I;16L",        16,     copy2},

    {NULL} /* sentinel */
};


ImagingShuffler
ImagingFindUnpacker(const char* mode, const char* rawmode, int* bits_out)
{
    int i;

    /* find a suitable pixel unpacker */
    for (i = 0; unpackers[i].rawmode; i++)
        if (strcmp(unpackers[i].mode, mode) == 0 &&
            strcmp(unpackers[i].rawmode, rawmode) == 0) {
            if (bits_out)
                *bits_out = unpackers[i].bits;
            return unpackers[i].unpack;
        }

    /* FIXME: configure a general unpacker based on the type codes... */

    return NULL;
}