/**
 * @file snd_mix.c
 * @brief Portable code to mix sounds for snd_ref.c.
 */

/*
All original materal Copyright (C) 2002-2007 UFO: Alien Invasion team.

15/06/06, Eddy Cullen (ScreamingWithNoSound):
	Reformatted to agreed style.
	Added doxygen file comment.
	Updated copyright notice.

Original file from Quake 2 v3.21: quake2-2.31/client/snd_mix.c
Copyright (C) 1997-2001 Id Software, Inc.

This program is free software; you can redistribute it and/or
modify it under the terms of the GNU General Public License
as published by the Free Software Foundation; either version 2
of the License, or (at your option) any later version.

This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.

See the GNU General Public License for more details.

You should have received a copy of the GNU General Public License
along with this program; if not, write to the Free Software
Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.

*/

#include "client.h"
#include "snd_loc.h"

#define	PAINTBUFFER_SIZE	2048
static portable_samplepair_t paintbuffer[PAINTBUFFER_SIZE];
static int snd_scaletable[32][256];
static int *snd_p, snd_linear_count, snd_vol;
static short *snd_out;

/**
 * @brief
 */
void S_WriteLinearBlastStereo16(void)
{
	int i;
	int val;

	for (i = 0; i < snd_linear_count; i += 2) {
		val = snd_p[i] >> 8;
		if (val > 0x7fff)
			snd_out[i] = 0x7fff;
		else if (val < (short) 0x8000)
			snd_out[i] = (short) 0x8000;
		else
			snd_out[i] = val;

		val = snd_p[i + 1] >> 8;
		if (val > 0x7fff)
			snd_out[i + 1] = 0x7fff;
		else if (val < (short) 0x8000)
			snd_out[i + 1] = (short) 0x8000;
		else
			snd_out[i + 1] = val;
	}
}

/**
 * @brief
 */
void S_TransferStereo16(unsigned long *pbuf, int endtime)
{
	int lpos;
	int lpaintedtime;

	snd_p = (int *) paintbuffer;
	lpaintedtime = paintedtime;

	while (lpaintedtime < endtime) {
		/* handle recirculating buffer issues */
		lpos = lpaintedtime & ((dma.samples >> 1) - 1);

		snd_out = (short *) pbuf + (lpos << 1);

		snd_linear_count = (dma.samples >> 1) - lpos;
		if (lpaintedtime + snd_linear_count > endtime)
			snd_linear_count = endtime - lpaintedtime;

		snd_linear_count <<= 1;

		/* write a linear blast of samples */
		S_WriteLinearBlastStereo16();

		snd_p += snd_linear_count;
		lpaintedtime += (snd_linear_count >> 1);

		if (CL_VideoRecording()) {
			if (cls.state == ca_active || cl_aviForceDemo->value) {
				CL_WriteAVIAudioFrame((byte *) snd_out, snd_linear_count << 1);
			}
		}
	}
}

/**
 * @brief
 * @sa S_TransferStereo16
 */
void S_TransferPaintBuffer(int endtime)
{
	int out_idx;
	int count;
	int out_mask;
	int *p;
	int step;
	int val;
	unsigned long *pbuf;

	pbuf = (unsigned long *) dma.buffer;

	if (snd_testsound->value) {
		int i;
		int count;

		/* write a fixed sine wave */
		count = (endtime - paintedtime);
		for (i = 0; i < count; i++)
			paintbuffer[i].left = paintbuffer[i].right = sin((paintedtime + i) * 0.1) * 20000 * 256;
	}


	if (dma.samplebits == 16 && dma.channels == 2) {	/* optimized case */
		S_TransferStereo16(pbuf, endtime);
	} else {					/* general case */
		p = (int *) paintbuffer;
		count = (endtime - paintedtime) * dma.channels;
		out_mask = dma.samples - 1;
		out_idx = paintedtime * dma.channels & out_mask;
		step = 3 - dma.channels;

		if (dma.samplebits == 16) {
			short *out = (short *) pbuf;

			while (count--) {
				val = *p >> 8;
				p += step;
				if (val > 0x7fff)
					val = 0x7fff;
				else if (val < (short) 0x8000)
					val = (short) 0x8000;
				out[out_idx] = val;
				out_idx = (out_idx + 1) & out_mask;
			}
		} else if (dma.samplebits == 8) {
			unsigned char *out = (unsigned char *) pbuf;

			while (count--) {
				val = *p >> 8;
				p += step;
				if (val > 0x7fff)
					val = 0x7fff;
				else if (val < (short) 0x8000)
					val = (short) 0x8000;
				out[out_idx] = (val >> 8) + 128;
				out_idx = (out_idx + 1) & out_mask;
			}
		}
	}
}


/*
===============================================================================
CHANNEL MIXING
===============================================================================
*/


/**
 * @brief
 */
void S_PaintChannelFrom8(channel_t * ch, sfxcache_t * sc, int count, int offset)
{
	int data;
	int *lscale, *rscale;
	unsigned char *sfx;
	int i;
	portable_samplepair_t *samp;

	if (ch->leftvol > 255)
		ch->leftvol = 255;
	if (ch->rightvol > 255)
		ch->rightvol = 255;

	/*ZOID-- >>11 has been changed to >>3, >>11 didn't make much sense */
	/*as it would always be zero. */
	lscale = snd_scaletable[ch->leftvol >> 3];
	rscale = snd_scaletable[ch->rightvol >> 3];
	sfx = (unsigned char *) sc->data + ch->pos;

	samp = &paintbuffer[offset];

	for (i = 0; i < count; i++, samp++) {
		data = sfx[i];
		samp->left += lscale[data];
		samp->right += rscale[data];
	}

	ch->pos += count;
}

/**
 * @brief
 */
void S_PaintChannelFrom16(channel_t * ch, sfxcache_t * sc, int count, int offset)
{
	int data;
	int left, right;
	int leftvol, rightvol;
	signed short *sfx;
	int i;
	portable_samplepair_t *samp;

	leftvol = ch->leftvol * snd_vol;
	rightvol = ch->rightvol * snd_vol;
	sfx = (signed short *) sc->data + ch->pos;

	samp = &paintbuffer[offset];
	for (i = 0; i < count; i++, samp++) {
		data = sfx[i];
		left = (data * leftvol) >> 8;
		right = (data * rightvol) >> 8;
		samp->left += left;
		samp->right += right;
	}

	ch->pos += count;
}

/**
 * @brief
 */
void S_PaintChannels(int endtime)
{
	int i = 0;
	int end;
	channel_t *ch;
	sfxcache_t *sc;
	int ltime, count;
	playsound_t *ps;

	snd_vol = snd_volume->value * 256;

/*	Com_Printf("%i to %i\n", paintedtime, endtime); */
	while (paintedtime < endtime) {
		/* if paintbuffer is smaller than DMA buffer */
		end = endtime;
		if (endtime - paintedtime > PAINTBUFFER_SIZE)
			end = paintedtime + PAINTBUFFER_SIZE;

		/* start any playsounds */
		for(;;) {
			ps = s_pendingplays.next;
			if (ps == &s_pendingplays || !ps)
				break;			/* no more pending sounds */
			if (ps->begin <= paintedtime) {
				S_IssuePlaysound(ps);
				continue;
			}

			if (ps->begin < end)
				end = ps->begin;	/* stop here */
			break;
		}

		if (++i >= 2)
			snd_vol *= .75;		/*normalize */

		if (s_rawend < paintedtime) {
/*			Com_Printf("clear\n"); */
			memset(paintbuffer, 0, (end - paintedtime) * sizeof(portable_samplepair_t));
		} else {				/* copy from the streaming sound source */
			int s;
			int stop;

			stop = (end < s_rawend) ? end : s_rawend;

			for (i = paintedtime; i < stop; i++) {
				s = i & (MAX_RAW_SAMPLES - 1);
				paintbuffer[i - paintedtime] = s_rawsamples[s];
			}
/*			if (i != end) */
/*				Com_Printf("partial stream\n"); */
/*			else */
/*				Com_Printf("full stream\n"); */
			for (; i < end; i++) {
				paintbuffer[i - paintedtime].left = paintbuffer[i - paintedtime].right = 0;
			}
		}

		/* paint in the channels. */
		ch = channels;
		for (i = 0; i < MAX_CHANNELS; i++, ch++) {
			ltime = paintedtime;

			while (ltime < end) {
				if (!ch->sfx || (!ch->leftvol && !ch->rightvol))
					break;

				/* max painting is to the end of the buffer */
				count = end - ltime;

				/* might be stopped by running out of data */
				if (ch->end - ltime < count)
					count = ch->end - ltime;

				sc = S_LoadSound(ch->sfx);
				if (!sc)
					break;

				if (count > 0 && ch->sfx) {
					if (sc->width == 1)	/* FIXME; 8 bit asm is wrong now */
						S_PaintChannelFrom8(ch, sc, count, ltime - paintedtime);
					else
						S_PaintChannelFrom16(ch, sc, count, ltime - paintedtime);

					ltime += count;
				}

				/* if at end of loop, restart */
				if (ltime >= ch->end) {
					if (ch->autosound) {	/* autolooping sounds always go back to start */
						ch->pos = 0;
						ch->end = ltime + sc->length;
					} else if (sc->loopstart >= 0) {
						ch->pos = sc->loopstart;
						ch->end = ltime + sc->length - ch->pos;
					} else {	/* channel just stopped */
						ch->sfx = NULL;
					}
				}
			}
		}

		/* transfer out according to DMA format */
		S_TransferPaintBuffer(end);
		paintedtime = end;
	}
}

/**
 * @brief
 */
void S_InitScaletable(void)
{
	int i, j;
	int scale;

	snd_volume->modified = qfalse;
	for (i = 0; i < 32; i++) {
		scale = (int)(i * 8 * 256 * snd_volume->value);
		for (j = 0; j < 256; j++)
			/**
			 * When compiling with gcc-4.1.0 at optimisations O1 and
			 * higher, the tricky signed char type conversion is not
			 * guaranteed. Therefore we explicity calculate the signed
			 * value from the index as required. From Kevin Shanahan.
			 * Also see: http://gcc.gnu.org/bugzilla/show_bug.cgi?id=26719
			 * Note: should already be fixed in gcc
			 */
			snd_scaletable[i][j] = ((signed char) j) * scale;
			/* snd_scaletable[i][j] = ((j < 128) ? j : j - 0xff) * i * 8; */

	}
}