slice.c

linux下实现视频播放的播放器

	    NEEDBITS (bit_buf, bits, bit_ptr);

	    continue;

	} else if (bit_buf >= 0x04000000) {

	    tab = DCT_B14_8 + (UBITS (bit_buf, 8) - 4);

	    i += tab->run;
	    if (i < 64)
		goto normal_code;

	    /* escape code */

	    i += UBITS (bit_buf << 6, 6) - 64;
	    if (i >= 64)
		break;	/* illegal, check needed to avoid buffer overflow */

	    j = scan[i];

	    DUMPBITS (bit_buf, bits, 12);
	    NEEDBITS (bit_buf, bits, bit_ptr);
	    val = (SBITS (bit_buf, 12) * quant_matrix[j]) / 16;

	    SATURATE (val);
	    dest[j] = val;
	    mismatch ^= val;

	    DUMPBITS (bit_buf, bits, 12);
	    NEEDBITS (bit_buf, bits, bit_ptr);

	    continue;

	} else if (bit_buf >= 0x02000000) {
	    tab = DCT_B14_10 + (UBITS (bit_buf, 10) - 8);
	    i += tab->run;
	    if (i < 64)
		goto normal_code;
	} else if (bit_buf >= 0x00800000) {
	    tab = DCT_13 + (UBITS (bit_buf, 13) - 16);
	    i += tab->run;
	    if (i < 64)
		goto normal_code;
	} else if (bit_buf >= 0x00200000) {
	    tab = DCT_15 + (UBITS (bit_buf, 15) - 16);
	    i += tab->run;
	    if (i < 64)
		goto normal_code;
	} else {
	    tab = DCT_16 + UBITS (bit_buf, 16);
	    bit_buf <<= 16;
	    GETWORD (bit_buf, bits + 16, bit_ptr);
	    i += tab->run;
	    if (i < 64)
		goto normal_code;
	}
	break;	/* illegal, check needed to avoid buffer overflow */
    }
    dest[63] ^= mismatch & 16;
    DUMPBITS (bit_buf, bits, tab->len);	/* dump end of block code */
    decoder->bitstream_buf = bit_buf;
    decoder->bitstream_bits = bits;
    decoder->bitstream_ptr = bit_ptr;
}

static void get_intra_block_B15 (mpeg2_decoder_t * const decoder,
				 const uint16_t * const quant_matrix)
{
    int i;
    int j;
    int val;
    const uint8_t * const scan = decoder->scan;
    int mismatch;
    const DCTtab * tab;
    uint32_t bit_buf;
    int bits;
    const uint8_t * bit_ptr;
    int16_t * const dest = decoder->DCTblock;

    i = 0;
    mismatch = ~dest[0];

    bit_buf = decoder->bitstream_buf;
    bits = decoder->bitstream_bits;
    bit_ptr = decoder->bitstream_ptr;

    NEEDBITS (bit_buf, bits, bit_ptr);

    while (1) {
	if (bit_buf >= 0x04000000) {

	    tab = DCT_B15_8 + (UBITS (bit_buf, 8) - 4);

	    i += tab->run;
	    if (i < 64) {

	    normal_code:
		j = scan[i];
		bit_buf <<= tab->len;
		bits += tab->len + 1;
		val = (tab->level * quant_matrix[j]) >> 4;

		/* if (bitstream_get (1)) val = -val; */
		val = (val ^ SBITS (bit_buf, 1)) - SBITS (bit_buf, 1);

		SATURATE (val);
		dest[j] = val;
		mismatch ^= val;

		bit_buf <<= 1;
		NEEDBITS (bit_buf, bits, bit_ptr);

		continue;

	    } else {

		/* end of block. I commented out this code because if we */
		/* dont exit here we will still exit at the later test :) */

		/* if (i >= 128) break;	*/	/* end of block */

		/* escape code */

		i += UBITS (bit_buf << 6, 6) - 64;
		if (i >= 64)
		    break;	/* illegal, check against buffer overflow */

		j = scan[i];

		DUMPBITS (bit_buf, bits, 12);
		NEEDBITS (bit_buf, bits, bit_ptr);
		val = (SBITS (bit_buf, 12) * quant_matrix[j]) / 16;

		SATURATE (val);
		dest[j] = val;
		mismatch ^= val;

		DUMPBITS (bit_buf, bits, 12);
		NEEDBITS (bit_buf, bits, bit_ptr);

		continue;

	    }
	} else if (bit_buf >= 0x02000000) {
	    tab = DCT_B15_10 + (UBITS (bit_buf, 10) - 8);
	    i += tab->run;
	    if (i < 64)
		goto normal_code;
	} else if (bit_buf >= 0x00800000) {
	    tab = DCT_13 + (UBITS (bit_buf, 13) - 16);
	    i += tab->run;
	    if (i < 64)
		goto normal_code;
	} else if (bit_buf >= 0x00200000) {
	    tab = DCT_15 + (UBITS (bit_buf, 15) - 16);
	    i += tab->run;
	    if (i < 64)
		goto normal_code;
	} else {
	    tab = DCT_16 + UBITS (bit_buf, 16);
	    bit_buf <<= 16;
	    GETWORD (bit_buf, bits + 16, bit_ptr);
	    i += tab->run;
	    if (i < 64)
		goto normal_code;
	}
	break;	/* illegal, check needed to avoid buffer overflow */
    }
    dest[63] ^= mismatch & 16;
    DUMPBITS (bit_buf, bits, tab->len);	/* dump end of block code */
    decoder->bitstream_buf = bit_buf;
    decoder->bitstream_bits = bits;
    decoder->bitstream_ptr = bit_ptr;
}

static int get_non_intra_block (mpeg2_decoder_t * const decoder,
				const uint16_t * const quant_matrix)
{
    int i;
    int j;
    int val;
    const uint8_t * const scan = decoder->scan;
    int mismatch;
    const DCTtab * tab;
    uint32_t bit_buf;
    int bits;
    const uint8_t * bit_ptr;
    int16_t * const dest = decoder->DCTblock;

    i = -1;
    mismatch = -1;

    bit_buf = decoder->bitstream_buf;
    bits = decoder->bitstream_bits;
    bit_ptr = decoder->bitstream_ptr;

    NEEDBITS (bit_buf, bits, bit_ptr);
    if (bit_buf >= 0x28000000) {
	tab = DCT_B14DC_5 + (UBITS (bit_buf, 5) - 5);
	goto entry_1;
    } else
	goto entry_2;

    while (1) {
	if (bit_buf >= 0x28000000) {

	    tab = DCT_B14AC_5 + (UBITS (bit_buf, 5) - 5);

	entry_1:
	    i += tab->run;
	    if (i >= 64)
		break;	/* end of block */

	normal_code:
	    j = scan[i];
	    bit_buf <<= tab->len;
	    bits += tab->len + 1;
	    val = ((2 * tab->level + 1) * quant_matrix[j]) >> 5;

	    /* if (bitstream_get (1)) val = -val; */
	    val = (val ^ SBITS (bit_buf, 1)) - SBITS (bit_buf, 1);

	    SATURATE (val);
	    dest[j] = val;
	    mismatch ^= val;

	    bit_buf <<= 1;
	    NEEDBITS (bit_buf, bits, bit_ptr);

	    continue;

	}

    entry_2:
	if (bit_buf >= 0x04000000) {

	    tab = DCT_B14_8 + (UBITS (bit_buf, 8) - 4);

	    i += tab->run;
	    if (i < 64)
		goto normal_code;

	    /* escape code */

	    i += UBITS (bit_buf << 6, 6) - 64;
	    if (i >= 64)
		break;	/* illegal, check needed to avoid buffer overflow */

	    j = scan[i];

	    DUMPBITS (bit_buf, bits, 12);
	    NEEDBITS (bit_buf, bits, bit_ptr);
	    val = 2 * (SBITS (bit_buf, 12) + SBITS (bit_buf, 1)) + 1;
	    val = (val * quant_matrix[j]) / 32;

	    SATURATE (val);
	    dest[j] = val;
	    mismatch ^= val;

	    DUMPBITS (bit_buf, bits, 12);
	    NEEDBITS (bit_buf, bits, bit_ptr);

	    continue;

	} else if (bit_buf >= 0x02000000) {
	    tab = DCT_B14_10 + (UBITS (bit_buf, 10) - 8);
	    i += tab->run;
	    if (i < 64)
		goto normal_code;
	} else if (bit_buf >= 0x00800000) {
	    tab = DCT_13 + (UBITS (bit_buf, 13) - 16);
	    i += tab->run;
	    if (i < 64)
		goto normal_code;
	} else if (bit_buf >= 0x00200000) {
	    tab = DCT_15 + (UBITS (bit_buf, 15) - 16);
	    i += tab->run;
	    if (i < 64)
		goto normal_code;
	} else {
	    tab = DCT_16 + UBITS (bit_buf, 16);
	    bit_buf <<= 16;
	    GETWORD (bit_buf, bits + 16, bit_ptr);
	    i += tab->run;
	    if (i < 64)
		goto normal_code;
	}
	break;	/* illegal, check needed to avoid buffer overflow */
    }
    dest[63] ^= mismatch & 16;
    DUMPBITS (bit_buf, bits, tab->len);	/* dump end of block code */
    decoder->bitstream_buf = bit_buf;
    decoder->bitstream_bits = bits;
    decoder->bitstream_ptr = bit_ptr;
    return i;
}

static void get_mpeg1_intra_block (mpeg2_decoder_t * const decoder)
{
    int i;
    int j;
    int val;
    const uint8_t * const scan = decoder->scan;
    const uint16_t * const quant_matrix = decoder->quantizer_matrix[0];
    const DCTtab * tab;
    uint32_t bit_buf;
    int bits;
    const uint8_t * bit_ptr;
    int16_t * const dest = decoder->DCTblock;

    i = 0;

    bit_buf = decoder->bitstream_buf;
    bits = decoder->bitstream_bits;
    bit_ptr = decoder->bitstream_ptr;

    NEEDBITS (bit_buf, bits, bit_ptr);

    while (1) {
	if (bit_buf >= 0x28000000) {

	    tab = DCT_B14AC_5 + (UBITS (bit_buf, 5) - 5);

	    i += tab->run;
	    if (i >= 64)
		break;	/* end of block */

	normal_code:
	    j = scan[i];
	    bit_buf <<= tab->len;
	    bits += tab->len + 1;
	    val = (tab->level * quant_matrix[j]) >> 4;

	    /* oddification */
	    val = (val - 1) | 1;

	    /* if (bitstream_get (1)) val = -val; */
	    val = (val ^ SBITS (bit_buf, 1)) - SBITS (bit_buf, 1);

	    SATURATE (val);
	    dest[j] = val;

	    bit_buf <<= 1;
	    NEEDBITS (bit_buf, bits, bit_ptr);

	    continue;

	} else if (bit_buf >= 0x04000000) {

	    tab = DCT_B14_8 + (UBITS (bit_buf, 8) - 4);

	    i += tab->run;
	    if (i < 64)
		goto normal_code;

	    /* escape code */

	    i += UBITS (bit_buf << 6, 6) - 64;
	    if (i >= 64)
		break;	/* illegal, check needed to avoid buffer overflow */

	    j = scan[i];

	    DUMPBITS (bit_buf, bits, 12);
	    NEEDBITS (bit_buf, bits, bit_ptr);
	    val = SBITS (bit_buf, 8);
	    if (! (val & 0x7f)) {
		DUMPBITS (bit_buf, bits, 8);
		val = UBITS (bit_buf, 8) + 2 * val;
	    }
	    val = (val * quant_matrix[j]) / 16;

	    /* oddification */
	    val = (val + ~SBITS (val, 1)) | 1;

	    SATURATE (val);
	    dest[j] = val;

	    DUMPBITS (bit_buf, bits, 8);
	    NEEDBITS (bit_buf, bits, bit_ptr);

	    continue;

	} else if (bit_buf >= 0x02000000) {
	    tab = DCT_B14_10 + (UBITS (bit_buf, 10) - 8);
	    i += tab->run;
	    if (i < 64)
		goto normal_code;