// ITU-T H.222.0(10/2014)
// Information technology – Generic coding of moving pictures and associated audio information: Systems
// 2.5.5 Program stream directory(p84)

#include "mpeg-ps-proto.h"
#include <assert.h>

size_t psd_read(struct psd_t *psd, const uint8_t *data, size_t bytes)
{
    int i, j;
    uint16_t packet_length;
    uint16_t number_of_access_units;

    // Table 2-42 – Program stream directory packet(p81)
    assert(0x00 == data[0] && 0x00 == data[1] && 0x01 == data[2] && 0xFF == data[3]);
    packet_length = (((uint16_t)data[4]) << 8) | data[5];
    assert(bytes >= (size_t)packet_length + 6);

    assert((0x01 & data[7]) == 0x01); // 'xxxxxxx1'
    number_of_access_units = (data[6] << 8) | ((data[7] >> 7) & 0x7F);
    assert(number_of_access_units <= N_ACCESS_UNIT);

    assert((0x01 & data[9]) == 0x01); // 'xxxxxxx1'
    assert((0x01 & data[11]) == 0x01); // 'xxxxxxx1'
    assert((0x01 & data[13]) == 0x01); // 'xxxxxxx1'
    psd->prev_directory_offset = (uint64_t)(((uint64_t)data[8] << 38) | ((((uint64_t)data[9] >> 7) & 0x7F) << 30) | ((uint64_t)data[10] << 22) | ((((uint64_t)data[11] >> 7) & 0x7F) << 15) | ((uint64_t)data[12] << 7) | (((uint64_t)data[13] >> 7) & 0x7F));
    assert((0x01 & data[15]) == 0x01); // 'xxxxxxx1'
    assert((0x01 & data[17]) == 0x01); // 'xxxxxxx1'
    assert((0x01 & data[19]) == 0x01); // 'xxxxxxx1'
    psd->next_directory_offset = (uint64_t)(((uint64_t)data[14] << 38) | ((((uint64_t)data[15] >> 7) & 0x7F) << 30) | ((uint64_t)data[16] << 22) | ((((uint64_t)data[17] >> 7) & 0x7F) << 15) | ((uint64_t)data[18] << 7) | (((uint64_t)data[19] >> 7) & 0x7F));

    // access unit
    j = 20;
    for (i = 0; i < number_of_access_units; i++) {
        psd->units[i].packet_stream_id = data[j];
        psd->units[i].pes_header_position_offset_sign = (data[j + 1] >> 7) & 0x01;
        assert((0x01 & data[j + 2]) == 0x01); // 'xxxxxxx1'
        assert((0x01 & data[j + 4]) == 0x01); // 'xxxxxxx1'
        assert((0x01 & data[j + 6]) == 0x01); // 'xxxxxxx1'
        psd->units[i].pes_header_position_offset = (uint64_t)(((uint64_t)(data[j + 1] & 0x7F) << 38) | ((((uint64_t)data[j + 2] >> 7) & 0x7F) << 30) | ((uint64_t)data[j + 3] << 22) | ((((uint64_t)data[j + 4] >> 7) & 0x7F) << 15) | ((uint64_t)data[j + 5] << 7) | (((uint64_t)data[j + 6] >> 7) & 0x7F));
        psd->units[i].reference_offset = (data[j + 7] << 8) | data[j + 8];

        assert((0x81 & data[j + 9]) == 0x81); // '1xxxxxx1'
        if (psd->units[i].packet_stream_id == 0xFD) {
            psd->units[i].packet_stream_id_extension_msbs = (data[j + 9] >> 4) & 0x07;
        } else {
            assert((0x70 & data[j + 9]) == 0x00); // '1000xxx1'
        }

        assert((0x01 & data[j + 11]) == 0x01); // 'xxxxxxx1'
        assert((0x01 & data[j + 13]) == 0x01); // 'xxxxxxx1'
        psd->units[i].PTS = (uint64_t)(((uint64_t)((data[j + 9] >> 1) & 0x07) << 30) | ((uint64_t)data[j + 10] << 22) | ((((uint64_t)data[j + 11] >> 7) & 0x7F) << 15) | ((uint64_t)data[j + 12] << 7) | (((uint64_t)data[j + 13] >> 7) & 0x7F));

        assert((0x01 & data[j + 15]) == 0x01); // 'xxxxxxx1'
        psd->units[i].bytes_to_read = (uint32_t)(((uint32_t)data[j + 14] << 15) | (((data[j + 15] >> 1) & 0x7F) << 8) | data[j + 16]);

        assert((0x80 & data[j + 17]) == 0x80); // '1xxxxxxx'
        psd->units[i].intra_coded_indicator = (data[j + 17] >> 6) & 0x01;
        psd->units[i].coding_parameters_indicator = (data[j + 17] >> 4) & 0x03;
        if (0xFD == psd->units[i].packet_stream_id) {
            psd->units[i].packet_stream_id_extension_lsbs = data[j + 17] & 0x0F;
        } else {
            assert((0x0F & data[j + 17]) == 0x00); // '1xxx0000'
        }

        j += 18;
    }

    return j + 1;
}