/* getblk.c, DCT block decoding                                             */

/* Copyright (C) 1996, MPEG Software Simulation Group. All Rights Reserved. */

/*
 * Disclaimer of Warranty
 *
 * These software programs are available to the user without any license fee or
 * royalty on an "as is" basis.  The MPEG Software Simulation Group disclaims
 * any and all warranties, whether express, implied, or statuary, including any
 * implied warranties or merchantability or of fitness for a particular
 * purpose.  In no event shall the copyright-holder be liable for any
 * incidental, punitive, or consequential damages of any kind whatsoever
 * arising from the use of these programs.
 *
 * This disclaimer of warranty extends to the user of these programs and user's
 * customers, employees, agents, transferees, successors, and assigns.
 *
 * The MPEG Software Simulation Group does not represent or warrant that the
 * programs furnished hereunder are free of infringement of any third-party
 * patents.
 *
 * Commercial implementations of MPEG-1 and MPEG-2 video, including shareware,
 * are subject to royalty fees to patent holders.  Many of these patents are
 * general enough such that they are unavoidable regardless of implementation
 * design.
 *
 */

#include <stdio.h>

#include "config.h"
#include "global.h"


/* defined in getvlc.h */
typedef struct {
    char run, level, len;
} DCTtab;

extern DCTtab DCTtabfirst[], DCTtabnext[], DCTtab0[], DCTtab1[];
extern DCTtab DCTtab2[], DCTtab3[], DCTtab4[], DCTtab5[], DCTtab6[];
extern DCTtab DCTtab0a[], DCTtab1a[];


/* decode one intra coded MPEG-1 block */

void Decode_MPEG1_Intra_Block(comp, dc_dct_pred)
int comp;
int dc_dct_pred[];
{
    int val, i, j, sign;
    unsigned int code;
    DCTtab *tab;
    short *bp;

    bp = ld->block[comp];

    /* ISO/IEC 11172-2 section 2.4.3.7: Block layer. */
    /* decode DC coefficients */
    if (comp < 4)
	bp[0] = (dc_dct_pred[0] += Get_Luma_DC_dct_diff()) << 3;
    else if (comp == 4)
	bp[0] = (dc_dct_pred[1] += Get_Chroma_DC_dct_diff()) << 3;
    else
	bp[0] = (dc_dct_pred[2] += Get_Chroma_DC_dct_diff()) << 3;

    if (Fault_Flag)
	return;

    /* D-pictures do not contain AC coefficients */
    if (picture_coding_type == D_TYPE)
	return;

    /* decode AC coefficients */
    for (i = 1;; i++) {
	code = Show_Bits(16);
	if (code >= 16384)
	    tab = &DCTtabnext[(code >> 12) - 4];
	else if (code >= 1024)
	    tab = &DCTtab0[(code >> 8) - 4];
	else if (code >= 512)
	    tab = &DCTtab1[(code >> 6) - 8];
	else if (code >= 256)
	    tab = &DCTtab2[(code >> 4) - 16];
	else if (code >= 128)
	    tab = &DCTtab3[(code >> 3) - 16];
	else if (code >= 64)
	    tab = &DCTtab4[(code >> 2) - 16];
	else if (code >= 32)
	    tab = &DCTtab5[(code >> 1) - 16];
	else if (code >= 16)
	    tab = &DCTtab6[code - 16];
	else {
	    if (!Quiet_Flag)
		printf
		    ("invalid Huffman code in Decode_MPEG1_Intra_Block()\n");
	    Fault_Flag = 1;
	    return;
	}

	Flush_Buffer(tab->len);

	if (tab->run == 64)	/* end_of_block */
	    return;

	if (tab->run == 65) {	/* escape */
	    i += Get_Bits(6);

	    val = Get_Bits(8);
	    if (val == 0)
		val = Get_Bits(8);
	    else if (val == 128)
		val = Get_Bits(8) - 256;
	    else if (val > 128)
		val -= 256;

	    if ((sign = (val < 0)))
		val = -val;
	} else {
	    i += tab->run;
	    val = tab->level;
	    sign = Get_Bits(1);
	}

	if (i >= 64) {
	    if (!Quiet_Flag)
		fprintf(stderr,
			"DCT coeff index (i) out of bounds (intra)\n");
	    Fault_Flag = 1;
	    return;
	}

	j = scan[ZIG_ZAG][i];
	val =
	    (val * ld->quantizer_scale *
	     ld->intra_quantizer_matrix[j]) >> 3;

	/* mismatch control ('oddification') */
	if (val != 0)		/* should always be true, but it's not guaranteed */
	    val = (val - 1) | 1;	/* equivalent to: if ((val&1)==0) val = val - 1; */

	/* saturation */
	if (!sign)
	    bp[j] = (val > 2047) ? 2047 : val;	/* positive */
	else
	    bp[j] = (val > 2048) ? -2048 : -val;	/* negative */
    }
}


/* decode one non-intra coded MPEG-1 block */

void Decode_MPEG1_Non_Intra_Block(comp)
int comp;
{
    int val, i, j, sign;
    unsigned int code;
    DCTtab *tab;
    short *bp;

    bp = ld->block[comp];

    /* decode AC coefficients */
    for (i = 0;; i++) {
	code = Show_Bits(16);
	if (code >= 16384) {
	    if (i == 0)
		tab = &DCTtabfirst[(code >> 12) - 4];
	    else
		tab = &DCTtabnext[(code >> 12) - 4];
	} else if (code >= 1024)
	    tab = &DCTtab0[(code >> 8) - 4];
	else if (code >= 512)
	    tab = &DCTtab1[(code >> 6) - 8];
	else if (code >= 256)
	    tab = &DCTtab2[(code >> 4) - 16];
	else if (code >= 128)
	    tab = &DCTtab3[(code >> 3) - 16];
	else if (code >= 64)
	    tab = &DCTtab4[(code >> 2) - 16];
	else if (code >= 32)
	    tab = &DCTtab5[(code >> 1) - 16];
	else if (code >= 16)
	    tab = &DCTtab6[code - 16];
	else {
	    if (!Quiet_Flag)
		printf
		    ("invalid Huffman code in Decode_MPEG1_Non_Intra_Block()\n");
	    Fault_Flag = 1;
	    return;
	}

	Flush_Buffer(tab->len);

	if (tab->run == 64)	/* end_of_block */
	    return;

	if (tab->run == 65) {	/* escape */
	    i += Get_Bits(6);

	    val = Get_Bits(8);
	    if (val == 0)
		val = Get_Bits(8);
	    else if (val == 128)
		val = Get_Bits(8) - 256;
	    else if (val > 128)
		val -= 256;

	    if ((sign = (val < 0)))
		val = -val;
	} else {
	    i += tab->run;
	    val = tab->level;
	    sign = Get_Bits(1);
	}

	if (i >= 64) {
	    if (!Quiet_Flag)
		fprintf(stderr,
			"DCT coeff index (i) out of bounds (inter)\n");
	    Fault_Flag = 1;
	    return;
	}

	j = scan[ZIG_ZAG][i];
	val =
	    (((val << 1) + 1) * ld->quantizer_scale *
	     ld->non_intra_quantizer_matrix[j]) >> 4;

	/* mismatch control ('oddification') */
	if (val != 0)		/* should always be true, but it's not guaranteed */
	    val = (val - 1) | 1;	/* equivalent to: if ((val&1)==0) val = val - 1; */

	/* saturation */
	if (!sign)
	    bp[j] = (val > 2047) ? 2047 : val;	/* positive */
	else
	    bp[j] = (val > 2048) ? -2048 : -val;	/* negative */
    }
}


/* decode one intra coded MPEG-2 block */

void Decode_MPEG2_Intra_Block(comp, dc_dct_pred)
int comp;
int dc_dct_pred[];
{
    int val, i, j, sign, nc, cc, run;
    unsigned int code;
    DCTtab *tab;
    short *bp;
    int *qmat;
    struct layer_data *ld1;

    /* with data partitioning, data always goes to base layer */
    ld1 = (ld->scalable_mode == SC_DP) ? &base : ld;
    bp = ld1->block[comp];

    if (base.scalable_mode == SC_DP) {
	if (base.priority_breakpoint < 64)
	    ld = &enhan;
	else
	    ld = &base;
    }
    cc = (comp < 4) ? 0 : (comp & 1) + 1;

    qmat = (comp < 4 || chroma_format == CHROMA420)
	? ld1->intra_quantizer_matrix : ld1->chroma_intra_quantizer_matrix;

    /* ISO/IEC 13818-2 section 7.2.1: decode DC coefficients */
    if (cc == 0)
	val = (dc_dct_pred[0] += Get_Luma_DC_dct_diff());
    else if (cc == 1)
	val = (dc_dct_pred[1] += Get_Chroma_DC_dct_diff());
    else
	val = (dc_dct_pred[2] += Get_Chroma_DC_dct_diff());

    if (Fault_Flag)
	return;

    bp[0] = val << (3 - intra_dc_precision);

    nc = 0;

#ifdef TRACE
    if (Trace_Flag)
	printf("DCT(%d)i:", comp);
#endif				/* TRACE */

    /* decode AC coefficients */
    for (i = 1;; i++) {
	code = Show_Bits(16);
	if (code >= 16384 && !intra_vlc_format)
	    tab = &DCTtabnext[(code >> 12) - 4];
	else if (code >= 1024) {
	    if (intra_vlc_format)
		tab = &DCTtab0a[(code >> 8) - 4];
	    else
		tab = &DCTtab0[(code >> 8) - 4];
	} else if (code >= 512) {
	    if (intra_vlc_format)
		tab = &DCTtab1a[(code >> 6) - 8];
	    else
		tab = &DCTtab1[(code >> 6) - 8];
	} else if (code >= 256)
	    tab = &DCTtab2[(code >> 4) - 16];
	else if (code >= 128)
	    tab = &DCTtab3[(code >> 3) - 16];
	else if (code >= 64)
	    tab = &DCTtab4[(code >> 2) - 16];
	else if (code >= 32)
	    tab = &DCTtab5[(code >> 1) - 16];
	else if (code >= 16)
	    tab = &DCTtab6[code - 16];
	else {
	    if (!Quiet_Flag)
		printf
		    ("invalid Huffman code in Decode_MPEG2_Intra_Block()\n");
	    Fault_Flag = 1;
	    return;
	}

	Flush_Buffer(tab->len);

#ifdef TRACE
	if (Trace_Flag) {
	    printf(" (");
	    Print_Bits(code, 16, tab->len);
	}
#endif				/* TRACE */

	if (tab->run == 64) {	/* end_of_block */
#ifdef TRACE
	    if (Trace_Flag)
		printf("): EOB\n");
#endif				/* TRACE */
	    return;
	}

	if (tab->run == 65) {	/* escape */
#ifdef TRACE
	    if (Trace_Flag) {
		putchar(' ');
		Print_Bits(Show_Bits(6), 6, 6);
	    }
#endif				/* TRACE */

	    i += run = Get_Bits(6);

#ifdef TRACE
	    if (Trace_Flag) {
		putchar(' ');
		Print_Bits(Show_Bits(12), 12, 12);
	    }
#endif				/* TRACE */

	    val = Get_Bits(12);
	    if ((val & 2047) == 0) {
		if (!Quiet_Flag)
		    printf
			("invalid escape in Decode_MPEG2_Intra_Block()\n");
		Fault_Flag = 1;
		return;
	    }
	    if ((sign = (val >= 2048)))
		val = 4096 - val;
	} else {
	    i += run = tab->run;
	    val = tab->level;
	    sign = Get_Bits(1);

#ifdef TRACE
	    if (Trace_Flag)
		printf("%d", sign);
#endif				/* TRACE */
	}

	if (i >= 64) {
	    if (!Quiet_Flag)
		fprintf(stderr,
			"DCT coeff index (i) out of bounds (intra2)\n");
	    Fault_Flag = 1;
	    return;
	}
#ifdef TRACE
	if (Trace_Flag)
	    printf("): %d/%d", run, sign ? -val : val);
#endif				/* TRACE */

	j = scan[ld1->alternate_scan][i];
	val = (val * ld1->quantizer_scale * qmat[j]) >> 4;
	bp[j] = sign ? -val : val;
	nc++;

	if (base.scalable_mode == SC_DP
	    && nc == base.priority_breakpoint - 63) ld = &enhan;
    }
}


/* decode one non-intra coded MPEG-2 block */

void Decode_MPEG2_Non_Intra_Block(comp)
int comp;
{
    int val, i, j, sign, nc, run;
    unsigned int code;
    DCTtab *tab;
    short *bp;
    int *qmat;
    struct layer_data *ld1;

    /* with data partitioning, data always goes to base layer */
    ld1 = (ld->scalable_mode == SC_DP) ? &base : ld;
    bp = ld1->block[comp];

    if (base.scalable_mode == SC_DP) {
	if (base.priority_breakpoint < 64)
	    ld = &enhan;
	else
	    ld = &base;
    }
    qmat = (comp < 4 || chroma_format == CHROMA420)
	? ld1->non_intra_quantizer_matrix
	: ld1->chroma_non_intra_quantizer_matrix;

    nc = 0;

#ifdef TRACE
    if (Trace_Flag)
	printf("DCT(%d)n:", comp);
#endif				/* TRACE */

    /* decode AC coefficients */
    for (i = 0;; i++) {
	code = Show_Bits(16);
	if (code >= 16384) {
	    if (i == 0)
		tab = &DCTtabfirst[(code >> 12) - 4];
	    else
		tab = &DCTtabnext[(code >> 12) - 4];
	} else if (code >= 1024)
	    tab = &DCTtab0[(code >> 8) - 4];
	else if (code >= 512)
	    tab = &DCTtab1[(code >> 6) - 8];
	else if (code >= 256)
	    tab = &DCTtab2[(code >> 4) - 16];
	else if (code >= 128)
	    tab = &DCTtab3[(code >> 3) - 16];
	else if (code >= 64)
	    tab = &DCTtab4[(code >> 2) - 16];
	else if (code >= 32)
	    tab = &DCTtab5[(code >> 1) - 16];
	else if (code >= 16)
	    tab = &DCTtab6[code - 16];
	else {
	    if (!Quiet_Flag)
		printf
		    ("invalid Huffman code in Decode_MPEG2_Non_Intra_Block()\n");
	    Fault_Flag = 1;
	    return;
	}

	Flush_Buffer(tab->len);

#ifdef TRACE
	if (Trace_Flag) {
	    printf(" (");
	    Print_Bits(code, 16, tab->len);
	}
#endif				/* TRACE */

	if (tab->run == 64) {	/* end_of_block */
#ifdef TRACE
	    if (Trace_Flag)
		printf("): EOB\n");
#endif				/* TRACE */
	    return;
	}

	if (tab->run == 65) {	/* escape */
#ifdef TRACE
	    if (Trace_Flag) {
		putchar(' ');
		Print_Bits(Show_Bits(6), 6, 6);
	    }
#endif				/* TRACE */

	    i += run = Get_Bits(6);

#ifdef TRACE
	    if (Trace_Flag) {
		putchar(' ');
		Print_Bits(Show_Bits(12), 12, 12);
	    }
#endif				/* TRACE */

	    val = Get_Bits(12);
	    if ((val & 2047) == 0) {
		if (!Quiet_Flag)
		    printf
			("invalid escape in Decode_MPEG2_Intra_Block()\n");
		Fault_Flag = 1;
		return;
	    }
	    if ((sign = (val >= 2048)))
		val = 4096 - val;
	} else {
	    i += run = tab->run;
	    val = tab->level;
	    sign = Get_Bits(1);

#ifdef TRACE
	    if (Trace_Flag)
		printf("%d", sign);
#endif				/* TRACE */
	}

	if (i >= 64) {
	    if (!Quiet_Flag)
		fprintf(stderr,
			"DCT coeff index (i) out of bounds (inter2)\n");
	    Fault_Flag = 1;
	    return;
	}
#ifdef TRACE
	if (Trace_Flag)
	    printf("): %d/%d", run, sign ? -val : val);
#endif				/* TRACE */

	j = scan[ld1->alternate_scan][i];
	val = (((val << 1) + 1) * ld1->quantizer_scale * qmat[j]) >> 5;
	bp[j] = sign ? -val : val;
	nc++;

	if (base.scalable_mode == SC_DP
	    && nc == base.priority_breakpoint - 63) ld = &enhan;
    }
}