/*
 * CoreAudio for 9front drawterm
 * kern/devaudio-core.c
 * link with -framework AudioToolbox
 * Copyright Space Aliens
 */
#include	<AudioToolbox/AudioQueue.h>
#undef		nil
#include	"u.h"
#include	"lib.h"
#include	"dat.h"
#include	"fns.h"
#include	"error.h"
#include	"devaudio.h"

enum
{
	Rate		= 44100,
	Channels	= 2,
	Bits		= 16,
	Buffers		= 4,
	BufferSize	= 4096 * 5,
	PacketSize	= 4,
};

static int isopen = 0;
static AudioStreamBasicDescription asbd;
static AudioQueueRef queue;
static AudioQueueBufferRef buffers[Buffers];
static uchar *rbuf = nil;
static ulong rbuflen = 0;
static int speed = Rate;
static int bufsz = BufferSize;

static void
audiodevcallback(void *unused, AudioQueueRef queue, AudioQueueBufferRef buffer)
{
	int n = bufsz;
	if(n > rbuflen)
		n = rbuflen;
	memcpy(buffer->mAudioData, rbuf, n);
	memset(&buffer->mAudioData[n], 0, bufsz - n);
	memmove(rbuf, rbuf + n, rbuflen - n);
	rbuflen -= n;
	buffer->mAudioDataByteSize = bufsz;
	AudioQueueEnqueueBuffer(queue, buffer, 0, nil);
}

static void
audiodevinit()
{
	int i;

	AudioQueueNewOutput(&asbd, audiodevcallback, nil, nil, nil, 0, &queue);
	for(i = 0; i < Buffers; i++){
		AudioQueueAllocateBuffer(queue, bufsz, &buffers[i]);
		buffers[i]->mAudioDataByteSize = bufsz;
		memset(buffers[i]->mAudioData, 0, bufsz);
		AudioQueueEnqueueBuffer(queue, buffers[i], 0, nil);
	}
	AudioQueueStart(queue, nil);
}

void
audiodevopen(void)
{
	if(isopen != 0)
		oserror();
	isopen = 1;
	
	asbd.mBitsPerChannel = Bits;
	asbd.mBytesPerFrame = Channels * (Bits/8);
	asbd.mFramesPerPacket = 1;
	asbd.mBytesPerPacket = PacketSize;
	asbd.mChannelsPerFrame = Channels;
	asbd.mFormatID = kAudioFormatLinearPCM;
	asbd.mFormatFlags = kLinearPCMFormatFlagIsSignedInteger;
	asbd.mSampleRate = speed;

	audiodevinit();
}

void
audiodevclose(void)
{
	while(rbuflen != 0)
		usleep(5);

	AudioQueueFlush(queue);
	AudioQueueStop(queue, 0);
	AudioQueueDispose(queue, 0);

	if(rbuf != nil){
		free(rbuf);
		rbuf = nil;
	}
	rbuflen = 0;

	isopen = 0;
}

int
audiodevread(void *a, int n)
{
	error("no reading");
	return -1;
}

int
audiodevwrite(void *a, int n)
{
	double tot;
    
	rbuf = realloc(rbuf, rbuflen + n);
	memcpy(rbuf + rbuflen, a, n);
	rbuflen += n;
    
	if (rbuflen > (bufsz*(Buffers/2))) {
		tot = (double)n/(speed*(Bits/8)*Channels);
		tot *= 1000;
		osmsleep((int)tot);
	}

	return n;
}

void
audiodevsetvol(int what, int left, int right)
{
	int i;

	if(what == Vspeed){
		speed = left;
		asbd.mSampleRate = speed;
		for(i = 1; ((i+1)*4096)<(speed/2); i++);
		bufsz = i * 4096;
		if(isopen){
			AudioQueueFlush(queue);
			AudioQueueStop(queue, 0);
			AudioQueueDispose(queue, 0);
			audiodevinit();
		}
	}
}

void
audiodevgetvol(int what, int *left, int *right)
{
	if(what == Vspeed){
		*left = *right = speed;
		return;
	}
	*left = *right = 100;
}