// SPDX-License-Identifier: LGPL-2.1+
/*
 * Copyright 2016 Tom aan de Wiel
 * Copyright 2018 Cisco Systems, Inc. and/or its affiliates. All rights reserved.
 *
 * 8x8 Fast Walsh Hadamard Transform in sequency order based on the paper:
 *
 * A Recursive Algorithm for Sequency-Ordered Fast Walsh Transforms,
 * R.D. Brown, 1977
 */

#include <linux/string.h>
#include <linux/kernel.h>
#include <linux/videodev2.h>
#include "codec-fwht.h"

#define OVERFLOW_BIT BIT(14)

/*
 * Note: bit 0 of the header must always be 0. Otherwise it cannot
 * be guaranteed that the magic 8 byte sequence (see below) can
 * never occur in the rlc output.
 */
#define PFRAME_BIT BIT(15)
#define DUPS_MASK 0x1ffe

#define PBLOCK 0
#define IBLOCK 1

#define ALL_ZEROS 15

static const uint8_t zigzag[64] = {
        0,
        1,  8,
        2,  9, 16,
        3, 10, 17, 24,
        4, 11, 18, 25, 32,
        5, 12, 19, 26, 33, 40,
        6, 13, 20, 27, 34, 41, 48,
        7, 14, 21, 28, 35, 42, 49, 56,
        15, 22, 29, 36, 43, 50, 57,
        23, 30, 37, 44, 51, 58,
        31, 38, 45, 52, 59,
        39, 46, 53, 60,
        47, 54, 61,
        55, 62,
        63,
};

/*
 * noinline_for_stack to work around
 * https://bugs.llvm.org/show_bug.cgi?id=38809
 */
static int noinline_for_stack
rlc(const s16 *in, __be16 *output, int blocktype)
{
        s16 block[8 * 8];
        s16 *wp = block;
        int i = 0;
        int x, y;
        int ret = 0;

        /* read in block from framebuffer */
        int lastzero_run = 0;
        int to_encode;

        for (y = 0; y < 8; y++) {
                for (x = 0; x < 8; x++) {
                        *wp = in[x + y * 8];
                        wp++;
                }
        }

        /* keep track of amount of trailing zeros */
        for (i = 63; i >= 0 && !block[zigzag[i]]; i--)
                lastzero_run++;

        *output++ = (blocktype == PBLOCK ? htons(PFRAME_BIT) : 0);
        ret++;

        to_encode = 8 * 8 - (lastzero_run > 14 ? lastzero_run : 0);

        i = 0;
        while (i < to_encode) {
                int cnt = 0;
                int tmp;

                /* count leading zeros */
                while ((tmp = block[zigzag[i]]) == 0 && cnt < 14) {
                        cnt++;
                        i++;
                        if (i == to_encode) {
                                cnt--;
                                break;
                        }
                }
                /* 4 bits for run, 12 for coefficient (quantization by 4) */
                *output++ = htons((cnt | tmp << 4));
                i++;
                ret++;
        }
        if (lastzero_run > 14) {
                *output = htons(ALL_ZEROS | 0);
                ret++;
        }

        return ret;
}

/*
 * This function will worst-case increase rlc_in by 65*2 bytes:
 * one s16 value for the header and 8 * 8 coefficients of type s16.
 */
static noinline_for_stack u16
derlc(const __be16 **rlc_in, s16 *dwht_out, const __be16 *end_of_input)
{
        /* header */
        const __be16 *input = *rlc_in;
        u16 stat;
        int dec_count = 0;
        s16 block[8 * 8 + 16];
        s16 *wp = block;
        int i;

        if (input > end_of_input)
                return OVERFLOW_BIT;
        stat = ntohs(*input++);

        /*
         * Now de-compress, it expands one byte to up to 15 bytes
         * (or fills the remainder of the 64 bytes with zeroes if it
         * is the last byte to expand).
         *
         * So block has to be 8 * 8 + 16 bytes, the '+ 16' is to
         * allow for overflow if the incoming data was malformed.
         */
        while (dec_count < 8 * 8) {
                s16 in;
                int length;
                int coeff;

                if (input > end_of_input)
                        return OVERFLOW_BIT;
                in = ntohs(*input++);
                length = in & 0xf;
                coeff = in >> 4;

                /* fill remainder with zeros */
                if (length == 15) {
                        for (i = 0; i < 64 - dec_count; i++)
                                *wp++ = 0;
                        break;
                }

                for (i = 0; i < length; i++)
                        *wp++ = 0;
                *wp++ = coeff;
                dec_count += length + 1;
        }

        wp = block;

        for (i = 0; i < 64; i++) {
                int pos = zigzag[i];
                int y = pos / 8;
                int x = pos % 8;

                dwht_out[x + y * 8] = *wp++;
        }
        *rlc_in = input;
        return stat;
}

static const int quant_table[] = {
        2, 2, 2, 2, 2, 2,  2,  2,
        2, 2, 2, 2, 2, 2,  2,  2,
        2, 2, 2, 2, 2, 2,  2,  3,
        2, 2, 2, 2, 2, 2,  3,  6,
        2, 2, 2, 2, 2, 3,  6,  6,
        2, 2, 2, 2, 3, 6,  6,  6,
        2, 2, 2, 3, 6, 6,  6,  6,
        2, 2, 3, 6, 6, 6,  6,  8,
};

static const int quant_table_p[] = {
        3, 3, 3, 3, 3, 3,  3,  3,
        3, 3, 3, 3, 3, 3,  3,  3,
        3, 3, 3, 3, 3, 3,  3,  3,
        3, 3, 3, 3, 3, 3,  3,  6,
        3, 3, 3, 3, 3, 3,  6,  6,
        3, 3, 3, 3, 3, 6,  6,  9,
        3, 3, 3, 3, 6, 6,  9,  9,
        3, 3, 3, 6, 6, 9,  9,  10,
};

static void quantize_intra(s16 *coeff, s16 *de_coeff, u16 qp)
{
        const int *quant = quant_table;
        int i, j;

        for (j = 0; j < 8; j++) {
                for (i = 0; i < 8; i++, quant++, coeff++, de_coeff++) {
                        *coeff >>= *quant;
                        if (*coeff >= -qp && *coeff <= qp)
                                *coeff = *de_coeff = 0;
                        else
                                *de_coeff = *coeff << *quant;
                }
        }
}

static void dequantize_intra(s16 *coeff)
{
        const int *quant = quant_table;
        int i, j;

        for (j = 0; j < 8; j++)
                for (i = 0; i < 8; i++, quant++, coeff++)
                        *coeff <<= *quant;
}

static void quantize_inter(s16 *coeff, s16 *de_coeff, u16 qp)
{
        const int *quant = quant_table_p;
        int i, j;

        for (j = 0; j < 8; j++) {
                for (i = 0; i < 8; i++, quant++, coeff++, de_coeff++) {
                        *coeff >>= *quant;
                        if (*coeff >= -qp && *coeff <= qp)
                                *coeff = *de_coeff = 0;
                        else
                                *de_coeff = *coeff << *quant;
                }
        }
}

static void dequantize_inter(s16 *coeff)
{
        const int *quant = quant_table_p;
        int i, j;

        for (j = 0; j < 8; j++)
                for (i = 0; i < 8; i++, quant++, coeff++)
                        *coeff <<= *quant;
}

static void noinline_for_stack fwht(const u8 *block, s16 *output_block,
                                    unsigned int stride,
                                    unsigned int input_step, bool intra)
{
        /* we'll need more than 8 bits for the transformed coefficients */
        s32 workspace1[8], workspace2[8];
        const u8 *tmp = block;
        s16 *out = output_block;
        int add = intra ? 256 : 0;
        unsigned int i;

        /* stage 1 */
        for (i = 0; i < 8; i++, tmp += stride, out += 8) {
                switch (input_step) {
                case 1:
                        workspace1[0]  = tmp[0] + tmp[1] - add;
                        workspace1[1]  = tmp[0] - tmp[1];

                        workspace1[2]  = tmp[2] + tmp[3] - add;
                        workspace1[3]  = tmp[2] - tmp[3];

                        workspace1[4]  = tmp[4] + tmp[5] - add;
                        workspace1[5]  = tmp[4] - tmp[5];

                        workspace1[6]  = tmp[6] + tmp[7] - add;
                        workspace1[7]  = tmp[6] - tmp[7];
                        break;
                case 2:
                        workspace1[0]  = tmp[0] + tmp[2] - add;
                        workspace1[1]  = tmp[0] - tmp[2];

                        workspace1[2]  = tmp[4] + tmp[6] - add;
                        workspace1[3]  = tmp[4] - tmp[6];

                        workspace1[4]  = tmp[8] + tmp[10] - add;
                        workspace1[5]  = tmp[8] - tmp[10];

                        workspace1[6]  = tmp[12] + tmp[14] - add;
                        workspace1[7]  = tmp[12] - tmp[14];
                        break;
                case 3:
                        workspace1[0]  = tmp[0] + tmp[3] - add;
                        workspace1[1]  = tmp[0] - tmp[3];

                        workspace1[2]  = tmp[6] + tmp[9] - add;
                        workspace1[3]  = tmp[6] - tmp[9];

                        workspace1[4]  = tmp[12] + tmp[15] - add;
                        workspace1[5]  = tmp[12] - tmp[15];

                        workspace1[6]  = tmp[18] + tmp[21] - add;
                        workspace1[7]  = tmp[18] - tmp[21];
                        break;
                default:
                        workspace1[0]  = tmp[0] + tmp[4] - add;
                        workspace1[1]  = tmp[0] - tmp[4];

                        workspace1[2]  = tmp[8] + tmp[12] - add;
                        workspace1[3]  = tmp[8] - tmp[12];

                        workspace1[4]  = tmp[16] + tmp[20] - add;
                        workspace1[5]  = tmp[16] - tmp[20];

                        workspace1[6]  = tmp[24] + tmp[28] - add;
                        workspace1[7]  = tmp[24] - tmp[28];
                        break;
                }

                /* stage 2 */
                workspace2[0] = workspace1[0] + workspace1[2];
                workspace2[1] = workspace1[0] - workspace1[2];
                workspace2[2] = workspace1[1] - workspace1[3];
                workspace2[3] = workspace1[1] + workspace1[3];

                workspace2[4] = workspace1[4] + workspace1[6];
                workspace2[5] = workspace1[4] - workspace1[6];
                workspace2[6] = workspace1[5] - workspace1[7];
                workspace2[7] = workspace1[5] + workspace1[7];

                /* stage 3 */
                out[0] = workspace2[0] + workspace2[4];
                out[1] = workspace2[0] - workspace2[4];
                out[2] = workspace2[1] - workspace2[5];
                out[3] = workspace2[1] + workspace2[5];
                out[4] = workspace2[2] + workspace2[6];
                out[5] = workspace2[2] - workspace2[6];
                out[6] = workspace2[3] - workspace2[7];
                out[7] = workspace2[3] + workspace2[7];
        }

        out = output_block;

        for (i = 0; i < 8; i++, out++) {
                /* stage 1 */
                workspace1[0]  = out[0] + out[1 * 8];
                workspace1[1]  = out[0] - out[1 * 8];

                workspace1[2]  = out[2 * 8] + out[3 * 8];
                workspace1[3]  = out[2 * 8] - out[3 * 8];

                workspace1[4]  = out[4 * 8] + out[5 * 8];
                workspace1[5]  = out[4 * 8] - out[5 * 8];

                workspace1[6]  = out[6 * 8] + out[7 * 8];
                workspace1[7]  = out[6 * 8] - out[7 * 8];

                /* stage 2 */
                workspace2[0] = workspace1[0] + workspace1[2];
                workspace2[1] = workspace1[0] - workspace1[2];
                workspace2[2] = workspace1[1] - workspace1[3];
                workspace2[3] = workspace1[1] + workspace1[3];

                workspace2[4] = workspace1[4] + workspace1[6];
                workspace2[5] = workspace1[4] - workspace1[6];
                workspace2[6] = workspace1[5] - workspace1[7];
                workspace2[7] = workspace1[5] + workspace1[7];
                /* stage 3 */
                out[0 * 8] = workspace2[0] + workspace2[4];
                out[1 * 8] = workspace2[0] - workspace2[4];
                out[2 * 8] = workspace2[1] - workspace2[5];
                out[3 * 8] = workspace2[1] + workspace2[5];
                out[4 * 8] = workspace2[2] + workspace2[6];
                out[5 * 8] = workspace2[2] - workspace2[6];
                out[6 * 8] = workspace2[3] - workspace2[7];
                out[7 * 8] = workspace2[3] + workspace2[7];
        }
}

/*
 * Not the nicest way of doing it, but P-blocks get twice the range of
 * that of the I-blocks. Therefore we need a type bigger than 8 bits.
 * Furthermore values can be negative... This is just a version that
 * works with 16 signed data
 */
static void noinline_for_stack
fwht16(const s16 *block, s16 *output_block, int stride, int intra)
{
        /* we'll need more than 8 bits for the transformed coefficients */
        s32 workspace1[8], workspace2[8];
        const s16 *tmp = block;
        s16 *out = output_block;
        int i;

        for (i = 0; i < 8; i++, tmp += stride, out += 8) {
                /* stage 1 */
                workspace1[0]  = tmp[0] + tmp[1];
                workspace1[1]  = tmp[0] - tmp[1];

                workspace1[2]  = tmp[2] + tmp[3];
                workspace1[3]  = tmp[2] - tmp[3];

                workspace1[4]  = tmp[4] + tmp[5];
                workspace1[5]  = tmp[4] - tmp[5];

                workspace1[6]  = tmp[6] + tmp[7];
                workspace1[7]  = tmp[6] - tmp[7];

                /* stage 2 */
                workspace2[0] = workspace1[0] + workspace1[2];
                workspace2[1] = workspace1[0] - workspace1[2];
                workspace2[2] = workspace1[1] - workspace1[3];
                workspace2[3] = workspace1[1] + workspace1[3];

                workspace2[4] = workspace1[4] + workspace1[6];
                workspace2[5] = workspace1[4] - workspace1[6];
                workspace2[6] = workspace1[5] - workspace1[7];
                workspace2[7] = workspace1[5] + workspace1[7];

                /* stage 3 */
                out[0] = workspace2[0] + workspace2[4];
                out[1] = workspace2[0] - workspace2[4];
                out[2] = workspace2[1] - workspace2[5];
                out[3] = workspace2[1] + workspace2[5];
                out[4] = workspace2[2] + workspace2[6];
                out[5] = workspace2[2] - workspace2[6];
                out[6] = workspace2[3] - workspace2[7];
                out[7] = workspace2[3] + workspace2[7];
        }

        out = output_block;

        for (i = 0; i < 8; i++, out++) {
                /* stage 1 */
                workspace1[0]  = out[0] + out[1*8];
                workspace1[1]  = out[0] - out[1*8];

                workspace1[2]  = out[2*8] + out[3*8];
                workspace1[3]  = out[2*8] - out[3*8];

                workspace1[4]  = out[4*8] + out[5*8];
                workspace1[5]  = out[4*8] - out[5*8];

                workspace1[6]  = out[6*8] + out[7*8];
                workspace1[7]  = out[6*8] - out[7*8];

                /* stage 2 */
                workspace2[0] = workspace1[0] + workspace1[2];
                workspace2[1] = workspace1[0] - workspace1[2];
                workspace2[2] = workspace1[1] - workspace1[3];
                workspace2[3] = workspace1[1] + workspace1[3];

                workspace2[4] = workspace1[4] + workspace1[6];
                workspace2[5] = workspace1[4] - workspace1[6];
                workspace2[6] = workspace1[5] - workspace1[7];
                workspace2[7] = workspace1[5] + workspace1[7];

                /* stage 3 */
                out[0*8] = workspace2[0] + workspace2[4];
                out[1*8] = workspace2[0] - workspace2[4];
                out[2*8] = workspace2[1] - workspace2[5];
                out[3*8] = workspace2[1] + workspace2[5];
                out[4*8] = workspace2[2] + workspace2[6];
                out[5*8] = workspace2[2] - workspace2[6];
                out[6*8] = workspace2[3] - workspace2[7];
                out[7*8] = workspace2[3] + workspace2[7];
        }
}

static noinline_for_stack void
ifwht(const s16 *block, s16 *output_block, int intra)
{
        /*
         * we'll need more than 8 bits for the transformed coefficients
         * use native unit of cpu
         */
        int workspace1[8], workspace2[8];
        int inter = intra ? 0 : 1;
        const s16 *tmp = block;
        s16 *out = output_block;
        int i;

        for (i = 0; i < 8; i++, tmp += 8, out += 8) {
                /* stage 1 */
                workspace1[0]  = tmp[0] + tmp[1];
                workspace1[1]  = tmp[0] - tmp[1];

                workspace1[2]  = tmp[2] + tmp[3];
                workspace1[3]  = tmp[2] - tmp[3];

                workspace1[4]  = tmp[4] + tmp[5];
                workspace1[5]  = tmp[4] - tmp[5];

                workspace1[6]  = tmp[6] + tmp[7];
                workspace1[7]  = tmp[6] - tmp[7];

                /* stage 2 */
                workspace2[0] = workspace1[0] + workspace1[2];
                workspace2[1] = workspace1[0] - workspace1[2];
                workspace2[2] = workspace1[1] - workspace1[3];
                workspace2[3] = workspace1[1] + workspace1[3];

                workspace2[4] = workspace1[4] + workspace1[6];
                workspace2[5] = workspace1[4] - workspace1[6];
                workspace2[6] = workspace1[5] - workspace1[7];
                workspace2[7] = workspace1[5] + workspace1[7];

                /* stage 3 */
                out[0] = workspace2[0] + workspace2[4];
                out[1] = workspace2[0] - workspace2[4];
                out[2] = workspace2[1] - workspace2[5];
                out[3] = workspace2[1] + workspace2[5];
                out[4] = workspace2[2] + workspace2[6];
                out[5] = workspace2[2] - workspace2[6];
                out[6] = workspace2[3] - workspace2[7];
                out[7] = workspace2[3] + workspace2[7];
        }

        out = output_block;

        for (i = 0; i < 8; i++, out++) {
                /* stage 1 */
                workspace1[0]  = out[0] + out[1 * 8];
                workspace1[1]  = out[0] - out[1 * 8];

                workspace1[2]  = out[2 * 8] + out[3 * 8];
                workspace1[3]  = out[2 * 8] - out[3 * 8];

                workspace1[4]  = out[4 * 8] + out[5 * 8];
                workspace1[5]  = out[4 * 8] - out[5 * 8];

                workspace1[6]  = out[6 * 8] + out[7 * 8];
                workspace1[7]  = out[6 * 8] - out[7 * 8];

                /* stage 2 */
                workspace2[0] = workspace1[0] + workspace1[2];
                workspace2[1] = workspace1[0] - workspace1[2];
                workspace2[2] = workspace1[1] - workspace1[3];
                workspace2[3] = workspace1[1] + workspace1[3];

                workspace2[4] = workspace1[4] + workspace1[6];
                workspace2[5] = workspace1[4] - workspace1[6];
                workspace2[6] = workspace1[5] - workspace1[7];
                workspace2[7] = workspace1[5] + workspace1[7];

                /* stage 3 */
                if (inter) {
                        int d;

                        out[0 * 8] = workspace2[0] + workspace2[4];
                        out[1 * 8] = workspace2[0] - workspace2[4];
                        out[2 * 8] = workspace2[1] - workspace2[5];
                        out[3 * 8] = workspace2[1] + workspace2[5];
                        out[4 * 8] = workspace2[2] + workspace2[6];
                        out[5 * 8] = workspace2[2] - workspace2[6];
                        out[6 * 8] = workspace2[3] - workspace2[7];
                        out[7 * 8] = workspace2[3] + workspace2[7];

                        for (d = 0; d < 8; d++)
                                out[8 * d] >>= 6;
                } else {
                        int d;

                        out[0 * 8] = workspace2[0] + workspace2[4];
                        out[1 * 8] = workspace2[0] - workspace2[4];
                        out[2 * 8] = workspace2[1] - workspace2[5];
                        out[3 * 8] = workspace2[1] + workspace2[5];
                        out[4 * 8] = workspace2[2] + workspace2[6];
                        out[5 * 8] = workspace2[2] - workspace2[6];
                        out[6 * 8] = workspace2[3] - workspace2[7];
                        out[7 * 8] = workspace2[3] + workspace2[7];

                        for (d = 0; d < 8; d++) {
                                out[8 * d] >>= 6;
                                out[8 * d] += 128;
                        }
                }
        }
}

static void fill_encoder_block(const u8 *input, s16 *dst,
                               unsigned int stride, unsigned int input_step)
{
        int i, j;

        for (i = 0; i < 8; i++) {
                for (j = 0; j < 8; j++, input += input_step)
                        *dst++ = *input;
                input += stride - 8 * input_step;
        }
}

static int var_intra(const s16 *input)
{
        int32_t mean = 0;
        int32_t ret = 0;
        const s16 *tmp = input;
        int i;

        for (i = 0; i < 8 * 8; i++, tmp++)
                mean += *tmp;
        mean /= 64;
        tmp = input;
        for (i = 0; i < 8 * 8; i++, tmp++)
                ret += (*tmp - mean) < 0 ? -(*tmp - mean) : (*tmp - mean);
        return ret;
}

static int var_inter(const s16 *old, const s16 *new)
{
        int32_t ret = 0;
        int i;

        for (i = 0; i < 8 * 8; i++, old++, new++)
                ret += (*old - *new) < 0 ? -(*old - *new) : (*old - *new);
        return ret;
}

static noinline_for_stack int
decide_blocktype(const u8 *cur, const u8 *reference, s16 *deltablock,
                 unsigned int stride, unsigned int input_step)
{
        s16 tmp[64];
        s16 old[64];
        s16 *work = tmp;
        unsigned int k, l;
        int vari;
        int vard;

        fill_encoder_block(cur, tmp, stride, input_step);
        fill_encoder_block(reference, old, 8, 1);
        vari = var_intra(tmp);

        for (k = 0; k < 8; k++) {
                for (l = 0; l < 8; l++) {
                        *deltablock = *work - *reference;
                        deltablock++;
                        work++;
                        reference++;
                }
        }
        deltablock -= 64;
        vard = var_inter(old, tmp);
        return vari <= vard ? IBLOCK : PBLOCK;
}

static void fill_decoder_block(u8 *dst, const s16 *input, int stride,
                               unsigned int dst_step)
{
        int i, j;

        for (i = 0; i < 8; i++) {
                for (j = 0; j < 8; j++, input++, dst += dst_step) {
                        if (*input < 0)
                                *dst = 0;
                        else if (*input > 255)
                                *dst = 255;
                        else
                                *dst = *input;
                }
                dst += stride - (8 * dst_step);
        }
}

static void add_deltas(s16 *deltas, const u8 *ref, int stride,
                       unsigned int ref_step)
{
        int k, l;

        for (k = 0; k < 8; k++) {
                for (l = 0; l < 8; l++) {
                        *deltas += *ref;
                        ref += ref_step;
                        /*
                         * Due to quantizing, it might possible that the
                         * decoded coefficients are slightly out of range
                         */
                        if (*deltas < 0)
                                *deltas = 0;
                        else if (*deltas > 255)
                                *deltas = 255;
                        deltas++;
                }
                ref += stride - (8 * ref_step);
        }
}

static u32 encode_plane(u8 *input, u8 *refp, __be16 **rlco, __be16 *rlco_max,
                        struct fwht_cframe *cf, u32 height, u32 width,
                        u32 stride, unsigned int input_step,
                        bool is_intra, bool next_is_intra)
{
        u8 *input_start = input;
        __be16 *rlco_start = *rlco;
        s16 deltablock[64];
        __be16 pframe_bit = htons(PFRAME_BIT);
        u32 encoding = 0;
        unsigned int last_size = 0;
        unsigned int i, j;

        width = round_up(width, 8);
        height = round_up(height, 8);

        for (j = 0; j < height / 8; j++) {
                input = input_start + j * 8 * stride;
                for (i = 0; i < width / 8; i++) {
                        /* intra code, first frame is always intra coded. */
                        int blocktype = IBLOCK;
                        unsigned int size;

                        if (!is_intra)
                                blocktype = decide_blocktype(input, refp,
                                        deltablock, stride, input_step);
                        if (blocktype == IBLOCK) {
                                fwht(input, cf->coeffs, stride, input_step, 1);
                                quantize_intra(cf->coeffs, cf->de_coeffs,
                                               cf->i_frame_qp);
                        } else {
                                /* inter code */
                                encoding |= FWHT_FRAME_PCODED;
                                fwht16(deltablock, cf->coeffs, 8, 0);
                                quantize_inter(cf->coeffs, cf->de_coeffs,
                                               cf->p_frame_qp);
                        }
                        if (!next_is_intra) {
                                ifwht(cf->de_coeffs, cf->de_fwht, blocktype);

                                if (blocktype == PBLOCK)
                                        add_deltas(cf->de_fwht, refp, 8, 1);
                                fill_decoder_block(refp, cf->de_fwht, 8, 1);
                        }

                        input += 8 * input_step;
                        refp += 8 * 8;

                        size = rlc(cf->coeffs, *rlco, blocktype);
                        if (last_size == size &&
                            !memcmp(*rlco + 1, *rlco - size + 1, 2 * size - 2)) {
                                __be16 *last_rlco = *rlco - size;
                                s16 hdr = ntohs(*last_rlco);

                                if (!((*last_rlco ^ **rlco) & pframe_bit) &&
                                    (hdr & DUPS_MASK) < DUPS_MASK)
                                        *last_rlco = htons(hdr + 2);
                                else
                                        *rlco += size;
                        } else {
                                *rlco += size;
                        }
                        if (*rlco >= rlco_max) {
                                encoding |= FWHT_FRAME_UNENCODED;
                                goto exit_loop;
                        }
                        last_size = size;
                }
        }

exit_loop:
        if (encoding & FWHT_FRAME_UNENCODED) {
                u8 *out = (u8 *)rlco_start;
                u8 *p;

                input = input_start;
                /*
                 * The compressed stream should never contain the magic
                 * header, so when we copy the YUV data we replace 0xff
                 * by 0xfe. Since YUV is limited range such values
                 * shouldn't appear anyway.
                 */
                for (j = 0; j < height; j++) {
                        for (i = 0, p = input; i < width; i++, p += input_step)
                                *out++ = (*p == 0xff) ? 0xfe : *p;
                        input += stride;
                }
                *rlco = (__be16 *)out;
                encoding &= ~FWHT_FRAME_PCODED;
        }
        return encoding;
}

u32 fwht_encode_frame(struct fwht_raw_frame *frm,
                      struct fwht_raw_frame *ref_frm,
                      struct fwht_cframe *cf,
                      bool is_intra, bool next_is_intra,
                      unsigned int width, unsigned int height,
                      unsigned int stride, unsigned int chroma_stride)
{
        unsigned int size = height * width;
        __be16 *rlco = cf->rlc_data;
        __be16 *rlco_max;
        u32 encoding;

        rlco_max = rlco + size / 2 - 256;
        encoding = encode_plane(frm->luma, ref_frm->luma, &rlco, rlco_max, cf,
                                height, width, stride,
                                frm->luma_alpha_step, is_intra, next_is_intra);
        if (encoding & FWHT_FRAME_UNENCODED)
                encoding |= FWHT_LUMA_UNENCODED;
        encoding &= ~FWHT_FRAME_UNENCODED;

        if (frm->components_num >= 3) {
                u32 chroma_h = height / frm->height_div;
                u32 chroma_w = width / frm->width_div;
                unsigned int chroma_size = chroma_h * chroma_w;

                rlco_max = rlco + chroma_size / 2 - 256;
                encoding |= encode_plane(frm->cb, ref_frm->cb, &rlco, rlco_max,
                                         cf, chroma_h, chroma_w,
                                         chroma_stride, frm->chroma_step,
                                         is_intra, next_is_intra);
                if (encoding & FWHT_FRAME_UNENCODED)
                        encoding |= FWHT_CB_UNENCODED;
                encoding &= ~FWHT_FRAME_UNENCODED;
                rlco_max = rlco + chroma_size / 2 - 256;
                encoding |= encode_plane(frm->cr, ref_frm->cr, &rlco, rlco_max,
                                         cf, chroma_h, chroma_w,
                                         chroma_stride, frm->chroma_step,
                                         is_intra, next_is_intra);
                if (encoding & FWHT_FRAME_UNENCODED)
                        encoding |= FWHT_CR_UNENCODED;
                encoding &= ~FWHT_FRAME_UNENCODED;
        }

        if (frm->components_num == 4) {
                rlco_max = rlco + size / 2 - 256;
                encoding |= encode_plane(frm->alpha, ref_frm->alpha, &rlco,
                                         rlco_max, cf, height, width,
                                         stride, frm->luma_alpha_step,
                                         is_intra, next_is_intra);
                if (encoding & FWHT_FRAME_UNENCODED)
                        encoding |= FWHT_ALPHA_UNENCODED;
                encoding &= ~FWHT_FRAME_UNENCODED;
        }

        cf->size = (rlco - cf->rlc_data) * sizeof(*rlco);
        return encoding;
}

static bool decode_plane(struct fwht_cframe *cf, const __be16 **rlco,
                         u32 height, u32 width, const u8 *ref, u32 ref_stride,
                         unsigned int ref_step, u8 *dst,
                         unsigned int dst_stride, unsigned int dst_step,
                         bool uncompressed, const __be16 *end_of_rlco_buf)
{
        unsigned int copies = 0;
        s16 copy[8 * 8];
        u16 stat;
        unsigned int i, j;
        bool is_intra = !ref;

        width = round_up(width, 8);
        height = round_up(height, 8);

        if (uncompressed) {
                int i;

                if (end_of_rlco_buf + 1 < *rlco + width * height / 2)
                        return false;
                for (i = 0; i < height; i++) {
                        memcpy(dst, *rlco, width);
                        dst += dst_stride;
                        *rlco += width / 2;
                }
                return true;
        }

        /*
         * When decoding each macroblock the rlco pointer will be increased
         * by 65 * 2 bytes worst-case.
         * To avoid overflow the buffer has to be 65/64th of the actual raw
         * image size, just in case someone feeds it malicious data.
         */
        for (j = 0; j < height / 8; j++) {
                for (i = 0; i < width / 8; i++) {
                        const u8 *refp = ref + j * 8 * ref_stride +
                                i * 8 * ref_step;
                        u8 *dstp = dst + j * 8 * dst_stride + i * 8 * dst_step;

                        if (copies) {
                                memcpy(cf->de_fwht, copy, sizeof(copy));
                                if ((stat & PFRAME_BIT) && !is_intra)
                                        add_deltas(cf->de_fwht, refp,
                                                   ref_stride, ref_step);
                                fill_decoder_block(dstp, cf->de_fwht,
                                                   dst_stride, dst_step);
                                copies--;
                                continue;
                        }

                        stat = derlc(rlco, cf->coeffs, end_of_rlco_buf);
                        if (stat & OVERFLOW_BIT)
                                return false;
                        if ((stat & PFRAME_BIT) && !is_intra)
                                dequantize_inter(cf->coeffs);
                        else
                                dequantize_intra(cf->coeffs);

                        ifwht(cf->coeffs, cf->de_fwht,
                              ((stat & PFRAME_BIT) && !is_intra) ? 0 : 1);

                        copies = (stat & DUPS_MASK) >> 1;
                        if (copies)
                                memcpy(copy, cf->de_fwht, sizeof(copy));
                        if ((stat & PFRAME_BIT) && !is_intra)
                                add_deltas(cf->de_fwht, refp,
                                           ref_stride, ref_step);
                        fill_decoder_block(dstp, cf->de_fwht, dst_stride,
                                           dst_step);
                }
        }
        return true;
}

bool fwht_decode_frame(struct fwht_cframe *cf, u32 hdr_flags,
                       unsigned int components_num, unsigned int width,
                       unsigned int height, const struct fwht_raw_frame *ref,
                       unsigned int ref_stride, unsigned int ref_chroma_stride,
                       struct fwht_raw_frame *dst, unsigned int dst_stride,
                       unsigned int dst_chroma_stride)
{
        const __be16 *rlco = cf->rlc_data;
        const __be16 *end_of_rlco_buf = cf->rlc_data +
                        (cf->size / sizeof(*rlco)) - 1;

        if (!decode_plane(cf, &rlco, height, width, ref->luma, ref_stride,
                          ref->luma_alpha_step, dst->luma, dst_stride,
                          dst->luma_alpha_step,
                          hdr_flags & V4L2_FWHT_FL_LUMA_IS_UNCOMPRESSED,
                          end_of_rlco_buf))
                return false;

        if (components_num >= 3) {
                u32 h = height;
                u32 w = width;

                if (!(hdr_flags & V4L2_FWHT_FL_CHROMA_FULL_HEIGHT))
                        h /= 2;
                if (!(hdr_flags & V4L2_FWHT_FL_CHROMA_FULL_WIDTH))
                        w /= 2;

                if (!decode_plane(cf, &rlco, h, w, ref->cb, ref_chroma_stride,
                                  ref->chroma_step, dst->cb, dst_chroma_stride,
                                  dst->chroma_step,
                                  hdr_flags & V4L2_FWHT_FL_CB_IS_UNCOMPRESSED,
                                  end_of_rlco_buf))
                        return false;
                if (!decode_plane(cf, &rlco, h, w, ref->cr, ref_chroma_stride,
                                  ref->chroma_step, dst->cr, dst_chroma_stride,
                                  dst->chroma_step,
                                  hdr_flags & V4L2_FWHT_FL_CR_IS_UNCOMPRESSED,
                                  end_of_rlco_buf))
                        return false;
        }

        if (components_num == 4)
                if (!decode_plane(cf, &rlco, height, width, ref->alpha, ref_stride,
                                  ref->luma_alpha_step, dst->alpha, dst_stride,
                                  dst->luma_alpha_step,
                                  hdr_flags & V4L2_FWHT_FL_ALPHA_IS_UNCOMPRESSED,
                                  end_of_rlco_buf))
                        return false;
        return true;
}