mpeg3dec.c

arm9开发板上的例子,可以学习一下有简单的c程序

static const ST_TYPE pow_io0[2][MAX_POS2] = {
	0x4000, 0x35D1, 0x4000, 0x2D41, 0x4000, 0x260D, 0x4000, 0x2000,
	0x4000, 0x1AE8, 0x4000, 0x16A0, 0x4000, 0x1306, 0x4000, 0x1000,
	0x4000, 0x0D74, 0x4000, 0x0B50, 0x4000, 0x0983, 0x4000, 0x0800,
	0x4000, 0x06BA, 0x4000, 0x05A8, 0x4000, 0x04C1, 0x4000, 0x0400,
	0x4000, 0x2D41, 0x4000, 0x2000, 0x4000, 0x16A0, 0x4000, 0x1000,
	0x4000, 0x0B50, 0x4000, 0x0800, 0x4000, 0x05A8, 0x4000, 0x0400,
	0x4000, 0x02D4, 0x4000, 0x0200, 0x4000, 0x016A, 0x4000, 0x0100,
	0x4000, 0x00B5, 0x4000, 0x0080, 0x4000, 0x005A, 0x4000, 0x0040
};

static const ST_TYPE pow_io1[2][MAX_POS2] = {
	0x4000, 0x4000, 0x35D1, 0x4000, 0x2D41, 0x4000, 0x260D, 0x4000,
	0x2000, 0x4000, 0x1AE8, 0x4000, 0x16A0, 0x4000, 0x1306, 0x4000,
	0x1000, 0x4000, 0x0D74, 0x4000, 0x0B50, 0x4000, 0x0983, 0x4000,
	0x0800, 0x4000, 0x06BA, 0x4000, 0x05A8, 0x4000, 0x04C1, 0x4000,
	0x4000, 0x4000, 0x2D41, 0x4000, 0x2000, 0x4000, 0x16A0, 0x4000,
	0x1000, 0x4000, 0x0B50, 0x4000, 0x0800, 0x4000, 0x05A8, 0x4000,
	0x0400, 0x4000, 0x02D4, 0x4000, 0x0200, 0x4000, 0x016A, 0x4000,
	0x0100, 0x4000, 0x00B5, 0x4000, 0x0080, 0x4000, 0x005A, 0x4000
};
#else

extern ST_TYPE *tan_pos0;
extern ST_TYPE *tan_pos1;
extern ST_TYPE (*pow_io0)[MAX_POS2];
extern ST_TYPE (*pow_io1)[MAX_POS2];
#endif //SRAM_OPT_TABLE

#else

#define ST_TYPE		REAL
#define ST_MULT(a, b)	((a) * (b))

static const ST_TYPE tan_pos0[MAX_POS1] = {
	0.0, 0.211324841, 0.366025358, 0.5, 0.633974493, 0.788674951, 1.0
};

static const ST_TYPE tan_pos1[MAX_POS1] = {
	1.0, 0.788674951, 0.633974493, 0.5, 0.366025358, 0.211324841, 0.0
};

static const ST_TYPE pow_io0[2][MAX_POS2] = {
	1.0, 0.840896368, 1.0, 0.707106769,
	1.0, 0.594603539, 1.0, 0.500000000,
	1.0, 0.420448184, 1.0, 0.353553385,
	1.0, 0.297301769, 1.0, 0.250000000,
	1.0, 0.210224092, 1.0, 0.176776692,
	1.0, 0.148650885, 1.0, 0.125000000,
	1.0, 0.105112046, 1.0, 0.088388346,
	1.0, 0.074325442, 1.0, 0.062500000,
	1.0, 0.707106769, 1.0, 0.500000000,
	1.0, 0.353553385, 1.0, 0.250000000,
	1.0, 0.176776692, 1.0, 0.125000000,
	1.0, 0.088388346, 1.0, 0.062500000,
	1.0, 0.044194173, 1.0, 0.031250000,
	1.0, 0.022097087, 1.0, 0.015625000,
	1.0, 0.011048543, 1.0, 0.007812500,
	1.0, 0.005524272, 1.0, 0.003906250,
};

static const ST_TYPE pow_io1[2][MAX_POS2] = {
	1.0, 1.0, 0.840896368, 1.0,
	0.707106769, 1.0, 0.594603539, 1.0,
	0.500000000, 1.0, 0.420448184, 1.0,
	 0.353553385, 1.0, 0.297301769, 1.0,
	0.250000000, 1.0, 0.210224092, 1.0,
	0.176776692, 1.0, 0.148650885, 1.0,
	0.125000000, 1.0, 0.105112046, 1.0,
	0.088388346, 1.0, 0.074325442, 1.0,
	1.0, 1.0, 0.707106769, 1.0,
	0.500000000, 1.0, 0.353553385, 1.0,
	0.250000000, 1.0, 0.176776692, 1.0,
	0.125000000, 1.0, 0.088388346, 1.0,
	0.062500000, 1.0, 0.044194173, 1.0,
	0.031250000, 1.0, 0.022097087, 1.0,
	0.015625000, 1.0, 0.011048543, 1.0,
	 0.007812500, 1.0, 0.005524272, 1.0,
};

#endif

/****************************************************************************/

/*
 *	Decode the stereo data of a granule
 *	Return 0 if Ok
 */
#ifdef MOV_FUNC
int (*MPEG3_stereo_cp)(MPA_STREAM *mps, MPEGAUD_FRACT_TYPE *xr, INT16 gr);
#endif

int MPEG3_stereo(MPA_STREAM *mps, MPEGAUD_FRACT_TYPE *xr, INT16 gr)
{
	static int init = 0;
	static FILE *fquant;

	const INT16 *band_l = sfBandIndex_l[mps->header.ID][mps->header.sampling_frequency];
	const INT16 *band_s = sfBandIndex_s[mps->header.ID][mps->header.sampling_frequency];
	MPA_SCALE_FAC3 *sf = &mps->scale_fac3[1];
	MPA_GRANULE_INFO *gi = &mps->side_info.ch[0].gr[gr];

	BOOL ms_stereo = (mps->header.mode == MPA_MODE_JOINT_STEREO) &&
		(mps->header.mode_extension & 0x2);
	BOOL i_stereo = (mps->header.mode == MPA_MODE_JOINT_STEREO) &&
		(mps->header.mode_extension & 0x1);

	INT16 sfb;
	INT16 i, j, sb, sbmax;
	BOOL lsf = (mps->header.ID == MPA_ID_2);

#define MAX_POS1	7
#define MAX_POS2	32

	const ST_TYPE *pow_iok0;
	const ST_TYPE *pow_iok1;
	MPEGAUD_FRACT_TYPE *xrp0, *xrp1, temp;
#ifdef MPEGAUD_INT
	ST_TYPE sq2 = 0.7071067812 * (1 << ST_BITS);
#else
	REAL sq2 = 0.7071067812;
#endif

	if (lsf) {
		if (gi->scalefac_compress & 1) {
			pow_iok0 = pow_io0[1];
			pow_iok1 = pow_io1[1];
		} else {
			pow_iok0 = pow_io0[0];
			pow_iok1 = pow_io1[0];
		}
	} else {
		pow_iok0 = tan_pos0;
		pow_iok1 = tan_pos1;
	}

	if ((mps->stereo) && i_stereo) {
		ST_TYPE k0, k1;
		INT16 sfb_top;
		INT16 max_sfb = 0;
		INT16 ispos;
		INT16 is_illegal;

		if (gi->window_switching_flag && (gi->block_type == 2)) {
			sbmax = mps->sfb_nul_s_top[0];
			if (sbmax < mps->sfb_nul_s_top[1])
				sbmax = mps->sfb_nul_s_top[1];
			sbmax++;
			if (sbmax > 13)
				sbmax = 13;

			for (j = 0; j < 3; j++) {
				sfb_top = mps->sfb_nul_s[j][1];
				if ((gi->mixed_block_flag) && (sfb_top < 3))
					sfb_top = 3;	// Normaly not !!!
				if (sfb_top > max_sfb)
					max_sfb = sfb_top;

				is_illegal = (lsf) ? mps->is_max_s[j][0] : 7;
				// Implicit: ispos == is_illegal here (not nul bands)
				ispos = is_illegal;
				for (sfb = 0; sfb < sfb_top; sfb++) {
					sb = band_s[sfb + 1] - band_s[sfb];

					i = 3 * band_s[sfb] + j * sb;
					xrp0 = &xr[i];
					xrp1 = &xr[MPA_GRANULE_SIZE + i];

					if (ms_stereo)
						while (sb--) {
							temp = ST_MULT((*xrp0 + *xrp1), sq2);
							*xrp1 = ST_MULT((*xrp0 - *xrp1), sq2);
							*xrp0++ = temp;
							xrp1++;
						}
				}
				while (sfb < sbmax) {
					// #9: sbmax instead of 13
					sb = band_s[sfb + 1] - band_s[sfb];

					i = 3 * band_s[sfb] + j * sb;
					xrp0 = &xr[i];
					xrp1 = &xr[MPA_GRANULE_SIZE + i];

					if (sfb < 12) {
						// keep previous ispos for
						// last sfb
						ispos = sf->s[j][sfb];
						is_illegal = (lsf) ? mps->
							is_max_s[j][sfb] : 7;
					}
					if (ispos == is_illegal) {
						if (ms_stereo)
							while (sb--) {
								temp = ST_MULT((*xrp0 + *xrp1), sq2);
								*xrp1 = ST_MULT((*xrp0 - *xrp1), sq2);
								*xrp0++ =
									temp;
								xrp1++;
							}
					} else {
						// ispos != is_illegal
						k0 = pow_iok0[ispos];
						k1 = pow_iok1[ispos];
						while (sb--) {
							temp = ST_MULT(*xrp0, k0);
							*xrp1 = ST_MULT(*xrp0, k1);
							*xrp0++ = temp;
							xrp1++;
						}
					}
					sfb++;
				}
			}
			if (gi->mixed_block_flag) {
				INT16 sfb_max = (lsf) ? 6 : 8;
				xrp0 = xr;
				xrp1 = &xr[MPA_GRANULE_SIZE];

				if (max_sfb <= 3) {
					// Top of nul bands in long blocks
					sfb = mps->sfb_nul_l[1];
					// Begin of nul bands
				} else {
					sfb = sfb_max;
					// Begin of nul band not in long blocks
				}
				sb = band_l[sfb];
				// Implicit: ispos == is_illegal here (not nul bands)
				if (ms_stereo)
					while (sb--) {
						temp = ST_MULT((*xrp0 + *xrp1), sq2);
						*xrp1 = ST_MULT((*xrp0 - *xrp1), sq2);
						*xrp0++ = temp;
						xrp1++;
				} else {
					xrp0 += sb;
					xrp1 += sb;
				}
				for (; sfb < sfb_max; sfb++) {
					sb = band_l[sfb + 1] - band_l[sfb];
					ispos = sf->l[sfb];
					is_illegal = (lsf) ? mps->
						is_max_l[sfb] : 7;
					if (ispos == is_illegal) {
						if (ms_stereo)
							while (sb--) {
								temp = ST_MULT((*xrp0 + *xrp1), sq2);
								*xrp1 = ST_MULT((*xrp0 - *xrp1), sq2);
								*xrp0++ = temp;
								xrp1++;
						} else {
							xrp0 += sb;
							xrp1 += sb;
						}
					} else {
						// ispos != is_illegal
						k0 = pow_iok0[ispos];
						k1 = pow_iok1[ispos];
						while (sb--) {
							temp = ST_MULT(*xrp0, k0);
							*xrp1 = ST_MULT(*xrp0, k1);
							*xrp0++ = temp;
							xrp1++;
						}
					}
				}
			}
		} else {
			// Long blocks, intensity stereo
			sbmax = mps->sfb_nul_l[0];
			if (sbmax < mps->sfb_nul_l[1])
				sbmax = mps->sfb_nul_l[1];
			sbmax++;
			if (sbmax > 22)
				sbmax = 22;

			xrp0 = xr;
			xrp1 = &xr[MPA_GRANULE_SIZE];

			sfb = mps->sfb_nul_l[1];	// Begin of nul bands
			sb = band_l[sfb];
			is_illegal = (lsf) ? mps->is_max_l[0] : 7;
			// Implicit: ispos == is_illegal here (not nul bands)
			ispos = is_illegal;
			if (ms_stereo)
				while (sb--) {
					temp = ST_MULT((*xrp0 + *xrp1), sq2);
					*xrp1 = ST_MULT((*xrp0 - *xrp1), sq2);
					*xrp0++ = temp;
					xrp1++;
			} else {
				xrp0 += sb;
				xrp1 += sb;
			}
			for (; sfb < sbmax; sfb++) {
				// sbmax instead of 22
				sb = band_l[sfb + 1] - band_l[sfb];
				if (sfb < 21) {
					// keep previous ispos for last sfb
					ispos = sf->l[sfb];
					is_illegal = (lsf) ? mps->
						is_max_l[sfb] : 7;
				}
				if (ispos == is_illegal) {
					if (ms_stereo)
						while (sb--) {
							temp = ST_MULT((*xrp0 + *xrp1), sq2);
							*xrp1 = ST_MULT((*xrp0 - *xrp1), sq2);
							*xrp0++ = temp;
							xrp1++;
					} else {
						xrp0 += sb;
						xrp1 += sb;
					}
				} else {
					// ispos != is_illegal
					k0 = pow_iok0[ispos];
					k1 = pow_iok1[ispos];
					while (sb--) {
						temp = ST_MULT(*xrp0, k0);
						*xrp1 = ST_MULT(*xrp0, k1);
						*xrp0++ = temp;
						xrp1++;
					}
				}
			}
		}
	} else if ((mps->stereo) && ms_stereo) {
		// MS stereo
		xrp0 = xr;
		xrp1 = &xr[MPA_GRANULE_SIZE];

		sb = mps->imdct_max[0];
		if (sb < mps->imdct_max[1])
			sb = mps->imdct_max[1];
		sb = (INT16) (sb + 1) * MPA_SSLIMIT;
		if (sb > MPA_GRANULE_SIZE)
			sb = MPA_GRANULE_SIZE;

		while (sb--) {
			temp = ST_MULT((*xrp0 + *xrp1), sq2);
			*xrp1 = ST_MULT((*xrp0 - *xrp1), sq2);
			*xrp0++ = temp;
			xrp1++;
		}
	} else {
		//Normal stereo or mono -> nothing to do !
	}

	return(MPEGDEC_ERR_NONE);
}

/****************************************************************************/

/*
 *	Decode the stereo data -> mono of a granule
 *	Return 0 if Ok
 */

static int MPEG3_stereo_mono(MPA_STREAM *mps, MPEGAUD_FRACT_TYPE *xr, INT16 gr)
{
	const INT16 *band_l = sfBandIndex_l[mps->header.ID][mps->header.sampling_frequency];
	const INT16 *band_s = sfBandIndex_s[mps->header.ID][mps->header.sampling_frequency];
	MPA_SCALE_FAC3 *sf = &mps->scale_fac3[1];
	MPA_GRANULE_INFO *gi = &mps->side_info.ch[0].gr[gr];

	BOOL ms_stereo = (mps->header.mode == MPA_MODE_JOINT_STEREO) &&
		(mps->header.mode_extension & 0x2);
	BOOL i_stereo = (mps->header.mode == MPA_MODE_JOINT_STEREO) &&
		(mps->header.mode_extension & 0x1);

	INT16 sfb;
	INT16 i, j, sb, sbmax;

	BOOL lsf = (mps->header.ID == MPA_ID_2);

#define MAX_POS1	7
#define MAX_POS2	32

	const ST_TYPE *pow_iok0;
	MPEGAUD_FRACT_TYPE *xrp0, *xrp1;
#ifdef MPEGAUD_INT
	ST_TYPE sq2 = 0.7071067812 * (1 << ST_BITS);
#else
	REAL sq2 = 0.7071067812;
#endif

	if (lsf) {
		if (gi->scalefac_compress & 1)
			pow_iok0 = pow_io0[1];
		else
			pow_iok0 = pow_io0[0];
	} else {
		pow_iok0 = tan_pos0;
	}

	if ((mps->stereo) && i_stereo) {
		ST_TYPE k0;
		INT16 sfb_top;
		INT16 max_sfb = 0;
		INT16 ispos;
		INT16 is_illegal;

		if (gi->window_switching_flag && (gi->block_type == 2)) {
			sbmax = mps->sfb_nul_s_top[0];
			if (sbmax < mps->sfb_nul_s_top[1])
				sbmax = mps->sfb_nul_s_top[1];
			sbmax++;
			if (sbmax > 13)
				sbmax = 13;

			for (j = 0; j < 3; j++) {
				sfb_top = mps->sfb_nul_s[j][1];
				if ((gi->mixed_block_flag) && (sfb_top < 3))
					sfb_top = 3;	// Normaly not !!!
				if (sfb_top > max_sfb)
					max_sfb = sfb_top;

				is_illegal = (lsf) ? mps->is_max_s[j][0] : 7;
				// Implicit: ispos == is_illegal here (not nul bands)
				ispos = is_illegal;
				for (sfb = 0; sfb < sfb_top; sfb++) {
					sb = band_s[sfb + 1] - band_s[sfb];

					i = 3 * band_s[sfb] + j * sb;
					xrp0 = &xr[i];
					xrp1 = &xr[MPA_GRANULE_SIZE + i];

					if (ms_stereo)
						while (sb--) {
							*xrp0 = ST_MULT((*xrp0 + *xrp1), sq2);
							xrp0++;
							xrp1++;
						}
				}
				while (sfb < sbmax) {
					// #9: sbmax instead of 13
					sb = band_s[sfb + 1] - band_s[sfb];

					i = 3 * band_s[sfb] + j * sb;
					xrp0 = &xr[i];
					xrp1 = &xr[MPA_GRANULE_SIZE + i];

					if (sfb < 12) {
						// keep previous ispos for
						// last sfb
						ispos = sf->s[j][sfb];
						is_illegal = (lsf) ? mps->
							is_max_s[j][sfb] : 7;
					}
					if (ispos == is_illegal) {
						if (ms_stereo)
							while (sb--) {
								*xrp0 = ST_MULT((*xrp0 + *xrp1), sq2);
								xrp0++;