/* putvlc.c, generation of variable length codes                            */

/* 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"
#include "vlc.h"

/* private prototypes */
static void putDC _ANSI_ARGS_((sVLCtable * tab, int val));

/* generate variable length code for luminance DC coefficient */
void putDClum(val)
int val;
{
    putDC(DClumtab, val);
}

/* generate variable length code for chrominance DC coefficient */
void putDCchrom(val)
int val;
{
    putDC(DCchromtab, val);
}

/* generate variable length code for DC coefficient (7.2.1) */
static void putDC(tab, val)
sVLCtable *tab;
int val;
{
    int absval, size;

    absval = (val < 0) ? -val : val;	/* abs(val) */

    if (absval > 2047 || (mpeg1 && absval > 255)) {
	/* should never happen */
	sprintf(errortext, "DC value out of range (%d)\n", val);
	error(errortext);
    }

    /* compute dct_dc_size */
    size = 0;

    while (absval) {
	absval >>= 1;
	size++;
    }

    /* generate VLC for dct_dc_size (Table B-12 or B-13) */
    putbits(tab[size].code, tab[size].len);

    /* append fixed length code (dc_dct_differential) */
    if (size != 0) {
	if (val >= 0)
	    absval = val;
	else
	    absval = val + (1 << size) - 1;	/* val + (2 ^ size) - 1 */
	putbits(absval, size);
    }
}

/* generate variable length code for first coefficient
 * of a non-intra block (7.2.2.2) */
void putACfirst(run, val)
int run, val;
{
    if (run == 0 && (val == 1 || val == -1))	/* these are treated differently */
	putbits(2 | (val < 0), 2);	/* generate '1s' (s=sign), (Table B-14, line 2) */
    else
	putAC(run, val, 0);	/* no difference for all others */
}

/* generate variable length code for other DCT coefficients (7.2.2) */
void putAC(run, signed_level, vlcformat)
int run, signed_level, vlcformat;
{
    int level, len;
    VLCtable *ptab = NULL;

    level = (signed_level < 0) ? -signed_level : signed_level;	/* abs(signed_level) */

    /* make sure run and level are valid */
    if (run < 0 || run > 63 || level == 0 || level > 2047
	|| (mpeg1 && level > 255)) {
	sprintf(errortext,
		"AC value out of range (run=%d, signed_level=%d)\n", run,
		signed_level);
	error(errortext);
    }

    len = 0;

    if (run < 2 && level < 41) {
	/* vlcformat selects either of Table B-14 / B-15 */
	if (vlcformat)
	    ptab = &dct_code_tab1a[run][level - 1];
	else
	    ptab = &dct_code_tab1[run][level - 1];

	len = ptab->len;
    } else if (run < 32 && level < 6) {
	/* vlcformat selects either of Table B-14 / B-15 */
	if (vlcformat)
	    ptab = &dct_code_tab2a[run - 2][level - 1];
	else
	    ptab = &dct_code_tab2[run - 2][level - 1];

	len = ptab->len;
    }

    if (len != 0) {		/* a VLC code exists */
	putbits(ptab->code, len);
	putbits(signed_level < 0, 1);	/* sign */
    } else {
	/* no VLC for this (run, level) combination: use escape coding (7.2.2.3) */
	putbits(1l, 6);		/* Escape */
	putbits(run, 6);	/* 6 bit code for run */
	if (mpeg1) {
	    /* ISO/IEC 11172-2 uses a 8 or 16 bit code */
	    if (signed_level > 127)
		putbits(0, 8);
	    if (signed_level < -127)
		putbits(128, 8);
	    putbits(signed_level, 8);
	} else {
	    /* ISO/IEC 13818-2 uses a 12 bit code, Table B-16 */
	    putbits(signed_level, 12);
	}
    }
}

/* generate variable length code for macroblock_address_increment (6.3.16) */
void putaddrinc(addrinc)
int addrinc;
{
    while (addrinc > 33) {
	putbits(0x08, 11);	/* macroblock_escape */
	addrinc -= 33;
    }

    putbits(addrinctab[addrinc - 1].code, addrinctab[addrinc - 1].len);
}

/* generate variable length code for macroblock_type (6.3.16.1) */
void putmbtype(pict_type, mb_type)
int pict_type, mb_type;
{
    putbits(mbtypetab[pict_type - 1][mb_type].code,
	    mbtypetab[pict_type - 1][mb_type].len);
}

/* generate variable length code for motion_code (6.3.16.3) */
void putmotioncode(motion_code)
int motion_code;
{
    int abscode;

    abscode = (motion_code >= 0) ? motion_code : -motion_code;	/* abs(motion_code) */
    putbits(motionvectab[abscode].code, motionvectab[abscode].len);
    if (motion_code != 0)
	putbits(motion_code < 0, 1);	/* sign, 0=positive, 1=negative */
}

/* generate variable length code for dmvector[t] (6.3.16.3), Table B-11 */
void putdmv(dmv)
int dmv;
{
    if (dmv == 0)
	putbits(0, 1);
    else if (dmv > 0)
	putbits(2, 2);
    else
	putbits(3, 2);
}

/* generate variable length code for coded_block_pattern (6.3.16.4)
 *
 * 4:2:2, 4:4:4 not implemented
 */
void putcbp(cbp)
int cbp;
{
    putbits(cbptable[cbp].code, cbptable[cbp].len);
}