// SPDX-License-Identifier: GPL-2.0
/*
 * Copyright (C) 2019 Pengutronix, Michael Tretter <kernel@pengutronix.de>
 *
 * Convert NAL units between raw byte sequence payloads (RBSP) and C structs
 *
 * The conversion is defined in "ITU-T Rec. H.264 (04/2017) Advanced video
 * coding for generic audiovisual services". Decoder drivers may use the
 * parser to parse RBSP from encoded streams and configure the hardware, if
 * the hardware is not able to parse RBSP itself.  Encoder drivers may use the
 * generator to generate the RBSP for SPS/PPS nal units and add them to the
 * encoded stream if the hardware does not generate the units.
 */

#include <linux/kernel.h>
#include <linux/types.h>
#include <linux/string.h>
#include <linux/v4l2-controls.h>

#include <linux/device.h>
#include <linux/export.h>
#include <linux/log2.h>

#include "nal-h264.h"
#include "nal-rbsp.h"

/*
 * See Rec. ITU-T H.264 (04/2017) Table 7-1 - NAL unit type codes, syntax
 * element categories, and NAL unit type classes
 */
enum nal_unit_type {
        SEQUENCE_PARAMETER_SET = 7,
        PICTURE_PARAMETER_SET = 8,
        FILLER_DATA = 12,
};

static void nal_h264_write_start_code_prefix(struct rbsp *rbsp)
{
        u8 *p = rbsp->data + DIV_ROUND_UP(rbsp->pos, 8);
        int i = 4;

        if (DIV_ROUND_UP(rbsp->pos, 8) + i > rbsp->size) {
                rbsp->error = -EINVAL;
                return;
        }

        p[0] = 0x00;
        p[1] = 0x00;
        p[2] = 0x00;
        p[3] = 0x01;

        rbsp->pos += i * 8;
}

static void nal_h264_read_start_code_prefix(struct rbsp *rbsp)
{
        u8 *p = rbsp->data + DIV_ROUND_UP(rbsp->pos, 8);
        int i = 4;

        if (DIV_ROUND_UP(rbsp->pos, 8) + i > rbsp->size) {
                rbsp->error = -EINVAL;
                return;
        }

        if (p[0] != 0x00 || p[1] != 0x00 || p[2] != 0x00 || p[3] != 0x01) {
                rbsp->error = -EINVAL;
                return;
        }

        rbsp->pos += i * 8;
}

static void nal_h264_write_filler_data(struct rbsp *rbsp)
{
        u8 *p = rbsp->data + DIV_ROUND_UP(rbsp->pos, 8);
        int i;

        /* Keep 1 byte extra for terminating the NAL unit */
        i = rbsp->size - DIV_ROUND_UP(rbsp->pos, 8) - 1;
        memset(p, 0xff, i);
        rbsp->pos += i * 8;
}

static void nal_h264_read_filler_data(struct rbsp *rbsp)
{
        u8 *p = rbsp->data + DIV_ROUND_UP(rbsp->pos, 8);

        while (*p == 0xff) {
                if (DIV_ROUND_UP(rbsp->pos, 8) > rbsp->size) {
                        rbsp->error = -EINVAL;
                        return;
                }

                p++;
                rbsp->pos += 8;
        }
}

static void nal_h264_rbsp_hrd_parameters(struct rbsp *rbsp,
                                         struct nal_h264_hrd_parameters *hrd)
{
        unsigned int i;

        if (!hrd) {
                rbsp->error = -EINVAL;
                return;
        }

        rbsp_uev(rbsp, &hrd->cpb_cnt_minus1);
        rbsp_bits(rbsp, 4, &hrd->bit_rate_scale);
        rbsp_bits(rbsp, 4, &hrd->cpb_size_scale);

        for (i = 0; i <= hrd->cpb_cnt_minus1; i++) {
                rbsp_uev(rbsp, &hrd->bit_rate_value_minus1[i]);
                rbsp_uev(rbsp, &hrd->cpb_size_value_minus1[i]);
                rbsp_bit(rbsp, &hrd->cbr_flag[i]);
        }

        rbsp_bits(rbsp, 5, &hrd->initial_cpb_removal_delay_length_minus1);
        rbsp_bits(rbsp, 5, &hrd->cpb_removal_delay_length_minus1);
        rbsp_bits(rbsp, 5, &hrd->dpb_output_delay_length_minus1);
        rbsp_bits(rbsp, 5, &hrd->time_offset_length);
}

static void nal_h264_rbsp_vui_parameters(struct rbsp *rbsp,
                                         struct nal_h264_vui_parameters *vui)
{
        if (!vui) {
                rbsp->error = -EINVAL;
                return;
        }

        rbsp_bit(rbsp, &vui->aspect_ratio_info_present_flag);
        if (vui->aspect_ratio_info_present_flag) {
                rbsp_bits(rbsp, 8, &vui->aspect_ratio_idc);
                if (vui->aspect_ratio_idc == 255) {
                        rbsp_bits(rbsp, 16, &vui->sar_width);
                        rbsp_bits(rbsp, 16, &vui->sar_height);
                }
        }

        rbsp_bit(rbsp, &vui->overscan_info_present_flag);
        if (vui->overscan_info_present_flag)
                rbsp_bit(rbsp, &vui->overscan_appropriate_flag);

        rbsp_bit(rbsp, &vui->video_signal_type_present_flag);
        if (vui->video_signal_type_present_flag) {
                rbsp_bits(rbsp, 3, &vui->video_format);
                rbsp_bit(rbsp, &vui->video_full_range_flag);

                rbsp_bit(rbsp, &vui->colour_description_present_flag);
                if (vui->colour_description_present_flag) {
                        rbsp_bits(rbsp, 8, &vui->colour_primaries);
                        rbsp_bits(rbsp, 8, &vui->transfer_characteristics);
                        rbsp_bits(rbsp, 8, &vui->matrix_coefficients);
                }
        }

        rbsp_bit(rbsp, &vui->chroma_loc_info_present_flag);
        if (vui->chroma_loc_info_present_flag) {
                rbsp_uev(rbsp, &vui->chroma_sample_loc_type_top_field);
                rbsp_uev(rbsp, &vui->chroma_sample_loc_type_bottom_field);
        }

        rbsp_bit(rbsp, &vui->timing_info_present_flag);
        if (vui->timing_info_present_flag) {
                rbsp_bits(rbsp, 32, &vui->num_units_in_tick);
                rbsp_bits(rbsp, 32, &vui->time_scale);
                rbsp_bit(rbsp, &vui->fixed_frame_rate_flag);
        }

        rbsp_bit(rbsp, &vui->nal_hrd_parameters_present_flag);
        if (vui->nal_hrd_parameters_present_flag)
                nal_h264_rbsp_hrd_parameters(rbsp, &vui->nal_hrd_parameters);

        rbsp_bit(rbsp, &vui->vcl_hrd_parameters_present_flag);
        if (vui->vcl_hrd_parameters_present_flag)
                nal_h264_rbsp_hrd_parameters(rbsp, &vui->vcl_hrd_parameters);

        if (vui->nal_hrd_parameters_present_flag ||
            vui->vcl_hrd_parameters_present_flag)
                rbsp_bit(rbsp, &vui->low_delay_hrd_flag);

        rbsp_bit(rbsp, &vui->pic_struct_present_flag);

        rbsp_bit(rbsp, &vui->bitstream_restriction_flag);
        if (vui->bitstream_restriction_flag) {
                rbsp_bit(rbsp, &vui->motion_vectors_over_pic_boundaries_flag);
                rbsp_uev(rbsp, &vui->max_bytes_per_pic_denom);
                rbsp_uev(rbsp, &vui->max_bits_per_mb_denom);
                rbsp_uev(rbsp, &vui->log2_max_mv_length_horizontal);
                rbsp_uev(rbsp, &vui->log21_max_mv_length_vertical);
                rbsp_uev(rbsp, &vui->max_num_reorder_frames);
                rbsp_uev(rbsp, &vui->max_dec_frame_buffering);
        }
}

static void nal_h264_rbsp_sps(struct rbsp *rbsp, struct nal_h264_sps *sps)
{
        unsigned int i;

        if (!sps) {
                rbsp->error = -EINVAL;
                return;
        }

        rbsp_bits(rbsp, 8, &sps->profile_idc);
        rbsp_bit(rbsp, &sps->constraint_set0_flag);
        rbsp_bit(rbsp, &sps->constraint_set1_flag);
        rbsp_bit(rbsp, &sps->constraint_set2_flag);
        rbsp_bit(rbsp, &sps->constraint_set3_flag);
        rbsp_bit(rbsp, &sps->constraint_set4_flag);
        rbsp_bit(rbsp, &sps->constraint_set5_flag);
        rbsp_bits(rbsp, 2, &sps->reserved_zero_2bits);
        rbsp_bits(rbsp, 8, &sps->level_idc);

        rbsp_uev(rbsp, &sps->seq_parameter_set_id);

        if (sps->profile_idc == 100 || sps->profile_idc == 110 ||
            sps->profile_idc == 122 || sps->profile_idc == 244 ||
            sps->profile_idc == 44 || sps->profile_idc == 83 ||
            sps->profile_idc == 86 || sps->profile_idc == 118 ||
            sps->profile_idc == 128 || sps->profile_idc == 138 ||
            sps->profile_idc == 139 || sps->profile_idc == 134 ||
            sps->profile_idc == 135) {
                rbsp_uev(rbsp, &sps->chroma_format_idc);

                if (sps->chroma_format_idc == 3)
                        rbsp_bit(rbsp, &sps->separate_colour_plane_flag);
                rbsp_uev(rbsp, &sps->bit_depth_luma_minus8);
                rbsp_uev(rbsp, &sps->bit_depth_chroma_minus8);
                rbsp_bit(rbsp, &sps->qpprime_y_zero_transform_bypass_flag);
                rbsp_bit(rbsp, &sps->seq_scaling_matrix_present_flag);
                if (sps->seq_scaling_matrix_present_flag)
                        rbsp->error = -EINVAL;
        }

        rbsp_uev(rbsp, &sps->log2_max_frame_num_minus4);

        rbsp_uev(rbsp, &sps->pic_order_cnt_type);
        switch (sps->pic_order_cnt_type) {
        case 0:
                rbsp_uev(rbsp, &sps->log2_max_pic_order_cnt_lsb_minus4);
                break;
        case 1:
                rbsp_bit(rbsp, &sps->delta_pic_order_always_zero_flag);
                rbsp_sev(rbsp, &sps->offset_for_non_ref_pic);
                rbsp_sev(rbsp, &sps->offset_for_top_to_bottom_field);

                rbsp_uev(rbsp, &sps->num_ref_frames_in_pic_order_cnt_cycle);
                for (i = 0; i < sps->num_ref_frames_in_pic_order_cnt_cycle; i++)
                        rbsp_sev(rbsp, &sps->offset_for_ref_frame[i]);
                break;
        default:
                rbsp->error = -EINVAL;
                break;
        }

        rbsp_uev(rbsp, &sps->max_num_ref_frames);
        rbsp_bit(rbsp, &sps->gaps_in_frame_num_value_allowed_flag);
        rbsp_uev(rbsp, &sps->pic_width_in_mbs_minus1);
        rbsp_uev(rbsp, &sps->pic_height_in_map_units_minus1);

        rbsp_bit(rbsp, &sps->frame_mbs_only_flag);
        if (!sps->frame_mbs_only_flag)
                rbsp_bit(rbsp, &sps->mb_adaptive_frame_field_flag);

        rbsp_bit(rbsp, &sps->direct_8x8_inference_flag);

        rbsp_bit(rbsp, &sps->frame_cropping_flag);
        if (sps->frame_cropping_flag) {
                rbsp_uev(rbsp, &sps->crop_left);
                rbsp_uev(rbsp, &sps->crop_right);
                rbsp_uev(rbsp, &sps->crop_top);
                rbsp_uev(rbsp, &sps->crop_bottom);
        }

        rbsp_bit(rbsp, &sps->vui_parameters_present_flag);
        if (sps->vui_parameters_present_flag)
                nal_h264_rbsp_vui_parameters(rbsp, &sps->vui);
}

static void nal_h264_rbsp_pps(struct rbsp *rbsp, struct nal_h264_pps *pps)
{
        int i;

        rbsp_uev(rbsp, &pps->pic_parameter_set_id);
        rbsp_uev(rbsp, &pps->seq_parameter_set_id);
        rbsp_bit(rbsp, &pps->entropy_coding_mode_flag);
        rbsp_bit(rbsp, &pps->bottom_field_pic_order_in_frame_present_flag);
        rbsp_uev(rbsp, &pps->num_slice_groups_minus1);
        if (pps->num_slice_groups_minus1 > 0) {
                rbsp_uev(rbsp, &pps->slice_group_map_type);
                switch (pps->slice_group_map_type) {
                case 0:
                        for (i = 0; i < pps->num_slice_groups_minus1; i++)
                                rbsp_uev(rbsp, &pps->run_length_minus1[i]);
                        break;
                case 2:
                        for (i = 0; i < pps->num_slice_groups_minus1; i++) {
                                rbsp_uev(rbsp, &pps->top_left[i]);
                                rbsp_uev(rbsp, &pps->bottom_right[i]);
                        }
                        break;
                case 3: case 4: case 5:
                        rbsp_bit(rbsp, &pps->slice_group_change_direction_flag);
                        rbsp_uev(rbsp, &pps->slice_group_change_rate_minus1);
                        break;
                case 6:
                        rbsp_uev(rbsp, &pps->pic_size_in_map_units_minus1);
                        for (i = 0; i < pps->pic_size_in_map_units_minus1; i++)
                                rbsp_bits(rbsp,
                                          order_base_2(pps->num_slice_groups_minus1 + 1),
                                          &pps->slice_group_id[i]);
                        break;
                default:
                        break;
                }
        }
        rbsp_uev(rbsp, &pps->num_ref_idx_l0_default_active_minus1);
        rbsp_uev(rbsp, &pps->num_ref_idx_l1_default_active_minus1);
        rbsp_bit(rbsp, &pps->weighted_pred_flag);
        rbsp_bits(rbsp, 2, &pps->weighted_bipred_idc);
        rbsp_sev(rbsp, &pps->pic_init_qp_minus26);
        rbsp_sev(rbsp, &pps->pic_init_qs_minus26);
        rbsp_sev(rbsp, &pps->chroma_qp_index_offset);
        rbsp_bit(rbsp, &pps->deblocking_filter_control_present_flag);
        rbsp_bit(rbsp, &pps->constrained_intra_pred_flag);
        rbsp_bit(rbsp, &pps->redundant_pic_cnt_present_flag);
        if (/* more_rbsp_data() */ false) {
                rbsp_bit(rbsp, &pps->transform_8x8_mode_flag);
                rbsp_bit(rbsp, &pps->pic_scaling_matrix_present_flag);
                if (pps->pic_scaling_matrix_present_flag)
                        rbsp->error = -EINVAL;
                rbsp_sev(rbsp, &pps->second_chroma_qp_index_offset);
        }
}

/**
 * nal_h264_write_sps() - Write SPS NAL unit into RBSP format
 * @dev: device pointer
 * @dest: the buffer that is filled with RBSP data
 * @n: maximum size of @dest in bytes
 * @sps: &struct nal_h264_sps to convert to RBSP
 *
 * Convert @sps to RBSP data and write it into @dest.
 *
 * The size of the SPS NAL unit is not known in advance and this function will
 * fail, if @dest does not hold sufficient space for the SPS NAL unit.
 *
 * Return: number of bytes written to @dest or negative error code
 */
ssize_t nal_h264_write_sps(const struct device *dev,
                           void *dest, size_t n, struct nal_h264_sps *sps)
{
        struct rbsp rbsp;
        unsigned int forbidden_zero_bit = 0;
        unsigned int nal_ref_idc = 0;
        unsigned int nal_unit_type = SEQUENCE_PARAMETER_SET;

        if (!dest)
                return -EINVAL;

        rbsp_init(&rbsp, dest, n, &write);

        nal_h264_write_start_code_prefix(&rbsp);

        rbsp_bit(&rbsp, &forbidden_zero_bit);
        rbsp_bits(&rbsp, 2, &nal_ref_idc);
        rbsp_bits(&rbsp, 5, &nal_unit_type);

        nal_h264_rbsp_sps(&rbsp, sps);

        rbsp_trailing_bits(&rbsp);

        if (rbsp.error)
                return rbsp.error;

        return DIV_ROUND_UP(rbsp.pos, 8);
}
EXPORT_SYMBOL_GPL(nal_h264_write_sps);

/**
 * nal_h264_read_sps() - Read SPS NAL unit from RBSP format
 * @dev: device pointer
 * @sps: the &struct nal_h264_sps to fill from the RBSP data
 * @src: the buffer that contains the RBSP data
 * @n: size of @src in bytes
 *
 * Read RBSP data from @src and use it to fill @sps.
 *
 * Return: number of bytes read from @src or negative error code
 */
ssize_t nal_h264_read_sps(const struct device *dev,
                          struct nal_h264_sps *sps, void *src, size_t n)
{
        struct rbsp rbsp;
        unsigned int forbidden_zero_bit;
        unsigned int nal_ref_idc;
        unsigned int nal_unit_type;

        if (!src)
                return -EINVAL;

        rbsp_init(&rbsp, src, n, &read);

        nal_h264_read_start_code_prefix(&rbsp);

        rbsp_bit(&rbsp, &forbidden_zero_bit);
        rbsp_bits(&rbsp, 2, &nal_ref_idc);
        rbsp_bits(&rbsp, 5, &nal_unit_type);

        if (rbsp.error ||
            forbidden_zero_bit != 0 ||
            nal_ref_idc != 0 ||
            nal_unit_type != SEQUENCE_PARAMETER_SET)
                return -EINVAL;

        nal_h264_rbsp_sps(&rbsp, sps);

        rbsp_trailing_bits(&rbsp);

        if (rbsp.error)
                return rbsp.error;

        return DIV_ROUND_UP(rbsp.pos, 8);
}
EXPORT_SYMBOL_GPL(nal_h264_read_sps);

/**
 * nal_h264_write_pps() - Write PPS NAL unit into RBSP format
 * @dev: device pointer
 * @dest: the buffer that is filled with RBSP data
 * @n: maximum size of @dest in bytes
 * @pps: &struct nal_h264_pps to convert to RBSP
 *
 * Convert @pps to RBSP data and write it into @dest.
 *
 * The size of the PPS NAL unit is not known in advance and this function will
 * fail, if @dest does not hold sufficient space for the PPS NAL unit.
 *
 * Return: number of bytes written to @dest or negative error code
 */
ssize_t nal_h264_write_pps(const struct device *dev,
                           void *dest, size_t n, struct nal_h264_pps *pps)
{
        struct rbsp rbsp;
        unsigned int forbidden_zero_bit = 0;
        unsigned int nal_ref_idc = 0;
        unsigned int nal_unit_type = PICTURE_PARAMETER_SET;

        if (!dest)
                return -EINVAL;

        rbsp_init(&rbsp, dest, n, &write);

        nal_h264_write_start_code_prefix(&rbsp);

        /* NAL unit header */
        rbsp_bit(&rbsp, &forbidden_zero_bit);
        rbsp_bits(&rbsp, 2, &nal_ref_idc);
        rbsp_bits(&rbsp, 5, &nal_unit_type);

        nal_h264_rbsp_pps(&rbsp, pps);

        rbsp_trailing_bits(&rbsp);

        if (rbsp.error)
                return rbsp.error;

        return DIV_ROUND_UP(rbsp.pos, 8);
}
EXPORT_SYMBOL_GPL(nal_h264_write_pps);

/**
 * nal_h264_read_pps() - Read PPS NAL unit from RBSP format
 * @dev: device pointer
 * @pps: the &struct nal_h264_pps to fill from the RBSP data
 * @src: the buffer that contains the RBSP data
 * @n: size of @src in bytes
 *
 * Read RBSP data from @src and use it to fill @pps.
 *
 * Return: number of bytes read from @src or negative error code
 */
ssize_t nal_h264_read_pps(const struct device *dev,
                          struct nal_h264_pps *pps, void *src, size_t n)
{
        struct rbsp rbsp;

        if (!src)
                return -EINVAL;

        rbsp_init(&rbsp, src, n, &read);

        nal_h264_read_start_code_prefix(&rbsp);

        /* NAL unit header */
        rbsp.pos += 8;

        nal_h264_rbsp_pps(&rbsp, pps);

        rbsp_trailing_bits(&rbsp);

        if (rbsp.error)
                return rbsp.error;

        return DIV_ROUND_UP(rbsp.pos, 8);
}
EXPORT_SYMBOL_GPL(nal_h264_read_pps);

/**
 * nal_h264_write_filler() - Write filler data RBSP
 * @dev: device pointer
 * @dest: buffer to fill with filler data
 * @n: size of the buffer to fill with filler data
 *
 * Write a filler data RBSP to @dest with a size of @n bytes and return the
 * number of written filler data bytes.
 *
 * Use this function to generate dummy data in an RBSP data stream that can be
 * safely ignored by h264 decoders.
 *
 * The RBSP format of the filler data is specified in Rec. ITU-T H.264
 * (04/2017) 7.3.2.7 Filler data RBSP syntax.
 *
 * Return: number of filler data bytes (including marker) or negative error
 */
ssize_t nal_h264_write_filler(const struct device *dev, void *dest, size_t n)
{
        struct rbsp rbsp;
        unsigned int forbidden_zero_bit = 0;
        unsigned int nal_ref_idc = 0;
        unsigned int nal_unit_type = FILLER_DATA;

        if (!dest)
                return -EINVAL;

        rbsp_init(&rbsp, dest, n, &write);

        nal_h264_write_start_code_prefix(&rbsp);

        rbsp_bit(&rbsp, &forbidden_zero_bit);
        rbsp_bits(&rbsp, 2, &nal_ref_idc);
        rbsp_bits(&rbsp, 5, &nal_unit_type);

        nal_h264_write_filler_data(&rbsp);

        rbsp_trailing_bits(&rbsp);

        return DIV_ROUND_UP(rbsp.pos, 8);
}
EXPORT_SYMBOL_GPL(nal_h264_write_filler);

/**
 * nal_h264_read_filler() - Read filler data RBSP
 * @dev: device pointer
 * @src: buffer with RBSP data that is read
 * @n: maximum size of src that shall be read
 *
 * Read a filler data RBSP from @src up to a maximum size of @n bytes and
 * return the size of the filler data in bytes including the marker.
 *
 * This function is used to parse filler data and skip the respective bytes in
 * the RBSP data.
 *
 * The RBSP format of the filler data is specified in Rec. ITU-T H.264
 * (04/2017) 7.3.2.7 Filler data RBSP syntax.
 *
 * Return: number of filler data bytes (including marker) or negative error
 */
ssize_t nal_h264_read_filler(const struct device *dev, void *src, size_t n)
{
        struct rbsp rbsp;
        unsigned int forbidden_zero_bit;
        unsigned int nal_ref_idc;
        unsigned int nal_unit_type;

        if (!src)
                return -EINVAL;

        rbsp_init(&rbsp, src, n, &read);

        nal_h264_read_start_code_prefix(&rbsp);

        rbsp_bit(&rbsp, &forbidden_zero_bit);
        rbsp_bits(&rbsp, 2, &nal_ref_idc);
        rbsp_bits(&rbsp, 5, &nal_unit_type);

        if (rbsp.error)
                return rbsp.error;
        if (forbidden_zero_bit != 0 ||
            nal_ref_idc != 0 ||
            nal_unit_type != FILLER_DATA)
                return -EINVAL;

        nal_h264_read_filler_data(&rbsp);
        rbsp_trailing_bits(&rbsp);

        if (rbsp.error)
                return rbsp.error;

        return DIV_ROUND_UP(rbsp.pos, 8);
}
EXPORT_SYMBOL_GPL(nal_h264_read_filler);