audiosub.c

这是一个同样来自贝尔实验室的和UNIX有着渊源的操作系统, 其简洁的设计和实现易于我们学习和理解

#include <u.h>
#include <libc.h>
#include <thread.h>
#include "usb.h"
#include "usbaudio.h"
#include "usbaudioctl.h"

Namelist terminal_types[] = {
	{	0x100, "USB Terminal, undefined type"},
	{	0x101, "USB Streaming"},
	{	0x301, "Speaker"},
	{	0x603, "Line connector"},
	{	0, nil }
};

units[2][8];	/* rec and play units */
nunits[2];		/* number in use */

static int
findunit(int nr)
{
	int rec, i;
	for (rec = 0; rec < 2; rec++)
		for (i = 0; i < nunits[rec]; i++)
			if (units[rec][i] == nr)
				return rec;
	return -1;
}

void
audio_interface(Device *d, int n, ulong csp, void *bb, int nb) {
	byte *b = bb;
	int ctl, ch, u, x;
	byte *p;
	int class, subclass, ifc, dalt;
	Audioalt *aa;

	if ((dalt = (csp >> 24) & 0xff) == 0xff) dalt = -1;
	if ((ifc = (csp >> 16) & 0xff) == 0xff) ifc = -1;
	class = Class(csp);
	subclass = Subclass(csp);

	if (debug & Dbginfo) fprint(2, "%d.%d: ", class, subclass);
	switch (subclass) {
	case 1:	// control
		switch (b[2]) {
		case 0x01:
			if (debug & Dbginfo){
				fprint(2, "Class-Specific AC Interface Header Descriptor\n");
				fprint(2, "\tAudioDeviceClass release (bcd)%c%c%c%c, TotalLength %d, InCollection %d aInterfaceNr %d\n",
					'0'+((b[4]>>4)&0xf), '0'+(b[4]&0xf),
					'0'+((b[3]>>4)&0xf), '0'+(b[3]&0xf),
					b[5]|(b[6]<<8), b[7], b[8]);
			}
			break;
		case 0x02:	// input
			if (debug & Dbginfo){
				fprint(2, "Audio Input Terminal Descriptor\n");
				fprint(2, "\tbTerminalId %d, wTerminalType 0x%x (%s), bAssocTerminal %d bNrChannels %d, wChannelConfig %d, iChannelNames %d iTerminal %d\n",
					b[3], b[4]|(b[5]<<8),
					namefor(terminal_types, b[4]|(b[5]<<8)),
					b[6], b[7], b[8]|(b[9]<<8), b[10], b[11]);
			}
			if ((b[4]|b[5]<<8) == 0x101){
				if (verbose)
					fprint(2, "Audio output unit %d\n", b[3]);
				/* USB streaming input: play interface */
				units[Play][nunits[Play]++] = b[3];
			}else{
				if (verbose)
					fprint(2, "Device can record from %s\n",
						namefor(terminal_types, b[4]|(b[5]<<8)));
				/* Non-USB input: record interface */
				units[Record][nunits[Record]++] = b[3];
			}
			break;
		case 0x03:	// output
			if (debug & Dbginfo){
				fprint(2, "Audio Output Terminal Descriptor\n");
				fprint(2, "\tbTerminalId %d, wTerminalType 0x%x (%s), bAssocTerminal %d bSourceId %d, iTerminal %d\n",
					b[3], b[4]|(b[5]<<8),
					namefor(terminal_types, b[4]|(b[5]<<8)),
					b[6], b[7], b[8]);
			}
			if ((b[4]|b[5]<<8) == 0x101){
				if (verbose)
					fprint(2, "Audio input unit %d\n", b[3]);
				/* USB streaming output: record interface */
				units[Record][nunits[Record]++] = b[3];
				if (verbose)
					fprint(2, "Device can play to %s\n",
						namefor(terminal_types, b[4]|(b[5]<<8)));
				/* Non-USB output: play interface */
				units[Play][nunits[Play]++] = b[3];
			}
			break;
		case 0x04:
			if (verbose)
				fprint(2, "Audio Mixer Unit %d\n", b[3]);
			if (debug & Dbginfo){
				fprint(2, "\t%d bytes:", nb);
				for(ctl = 0; ctl < nb; ctl++)
					fprint(2, " 0x%2.2x", b[ctl]);
				fprint(2, "\n\tbUnitId %d, bNrInPins %d", b[3], b[4]);
			}
			if (b[4]){
				if(debug & Dbginfo) fprint(2, ", baSourceIDs: [%d", b[5]);
				u = findunit(b[5]);
				for (ctl = 1; ctl < b[4]; ctl++){
					if (u < 0)
						u = findunit(b[5+ctl]);
					else if ((x = findunit(b[5+ctl])) >= 0 && u != x && verbose)
						fprint(2, "\tMixer %d for output AND input\n", b[3]);
					if (debug & Dbginfo) fprint(2, ", %d", b[5+ctl]);
				}
				if (debug & Dbginfo) fprint(2, "]\n");
				if (u >= 0){
					units[u][nunits[u]++] = b[3];
					if (mixerid[u] >= 0)
						fprint(2, "Second mixer (%d, %d) on %s\n", mixerid[u], b[3], u?"record":"playback");
					mixerid[u] = b[3];
				}
				if (debug & Dbginfo){
					fprint(2, "Channels %d, config %d, ",
						b[ctl+5], b[ctl+5+1] | b[ctl+5+2] << 8);
					x = b[ctl+5] * b[4];
					fprint(2, "programmable: %d bits, 0x", x);
					x = (x + 7) >> 3;
					while(x--)
						fprint(2, "%2.2x", b[ctl+x+5+4]);
				}
			}
			break;
		case 0x05:
			if (verbose)
				fprint(2, "Audio Selector Unit %d\n", b[3]);
			if (debug & Dbginfo)
				fprint(2, "\tbUnitId %d, bNrInPins %d", b[3], b[4]);
			if (b[4]){
				u = findunit(b[5]);
				if (debug & Dbginfo) fprint(2, ", baSourceIDs: %s [%d",
					u?"record":"playback", b[5]);
				for (ctl = 1; ctl < b[4]; ctl++){
					if (u < 0)
						u = findunit(b[5+ctl]);
					else if ((x = findunit(b[5+ctl])) >= 0 && u != x && verbose)
						fprint(2, "\tSelector %d for output AND input\n", b[3]);
					if (debug & Dbginfo) fprint(2, ", %d", b[5+ctl]);
				}
				if (debug & Dbginfo) fprint(2, "]\n");
				if (u >= 0){
					units[u][nunits[u]++] = b[3];
					if (selectorid[u] >= 0)
						fprint(2, "Second selector (%d, %d) on %s\n", selectorid[u], b[3], u?"record":"playback");
					selectorid[u] = b[3];
				}
			}
			break;
		case 0x06:	// feature
			if (verbose) fprint(2, "Audio Feature Unit %d", b[3]);
			if (debug & Dbginfo)
				fprint(2, "\tbUnitId %d, bSourceId %d, bControlSize %d\n",
					b[3], b[4], b[5]);
			u = findunit(b[4]);
			if (u >= 0){
				if (verbose) fprint(2, " for %s\n", u?"Record":"Playback");
				units[u][nunits[u]++] = b[3];
				if (featureid[u] >= 0)
					if (verbose) fprint(2, "Second feature unit (%d, %d) on %s\n", featureid[u], b[3], u?"record":"playback");
				featureid[u] = b[3];
			}else
				if (verbose) fprint(2, ", not known what for\n");
			p = b + 6;
			for (ctl = 1; ctl < 0x0b; ctl++)
				if ((1<<(ctl-1)) & (b[6] | ((b[5]>1)?(b[7]<<8):0))) {
					if (verbose)
						fprint(2, "\t%s control on master channel\n",
							controls[0][ctl].name);
					if (u >= 0){
						controls[u][ctl].readable = 1;
						controls[u][ctl].settable = 1;
						controls[u][ctl].chans = 0;
					}
				}
			p += (b[5]>1)?2:1;
			for (ch = 0; ch < (nb - 8)/b[5]; ch++) {
				for (ctl = 1; ctl < 0x0b; ctl++)
					if ((1<<(ctl-1)) & (p[0] | ((b[5]>1)?(p[1]<<8):0))) {
						if (verbose)
							fprint(2, "\t%s control on channel %d\n",
								controls[0][ctl].name, ch+1);
						if (u >= 0){
							controls[u][ctl].readable = 1;
							controls[u][ctl].settable = 1;
							controls[u][ctl].chans |= 1 <<(ch+1);
						}
					}
				p += (b[5]>1)?2:1;
			}
			break;
		default:
			pcs_raw("audio control unknown", bb, nb);
		}
		break;
	case 2: // stream
		switch (b[2]) {
		case 0x01:
			if (debug & Dbginfo)
				fprint(2, "Audio stream for TerminalID %d, delay %d, format_tag %#ux\n",
					b[3], b[4], b[5] | (b[6]<<8));
			break;
		case 0x02:
			if (d->config[n]->iface[ifc]->dalt[dalt] == nil)
				d->config[n]->iface[ifc]->dalt[dalt] = mallocz(sizeof(Dalt),1);
			aa = (Audioalt *)d->config[n]->iface[ifc]->dalt[dalt]->devspec;
			if (aa == nil) {
				aa = mallocz(sizeof(Audioalt), 1);
				d->config[n]->iface[ifc]->dalt[dalt]->devspec = aa;
			}
			if (verbose){
				if (b[4] <= 2)
					fprint(2, "Interface %d, alt %d: %s, %d bits, ",
						ifc, dalt, (b[4] == 1)?"mono":"stereo", b[6]);
				else
					fprint(2, "Interface %d, alt %d: %d channels, %d bits, ",
						ifc, dalt, b[4], b[6]);
			}
			if(b[7] == 0){
				if (verbose)
					fprint(2, "frequency variable between %d and %d\n",
						b[8] | b[9]<<8 | b[10]<<16, b[11] | b[12]<<8 | b[13]<<16);
				aa->minfreq = b[8] | b[9]<<8 | b[10]<<16;
				aa->maxfreq = b[11] | b[12]<<8 | b[13]<<16;
				aa->caps |= has_contfreq;
			}else{
				if (verbose)
					fprint(2, "discrete frequencies are:");
				for (ch = 0; ch < b[7] && ch < 8; ch++){
					aa->freqs[ch] = b[8+3*ch] | b[9+3*ch]<<8 | b[10+3*ch]<<16;
					if (verbose)
						fprint(2, " %d", b[8+3*ch] | b[9+3*ch]<<8 | b[10+3*ch]<<16);
				}
				if (ch < 8)
					aa->freqs[ch] = -1;
				if (verbose)
					fprint(2, "\n");
				if (ch > 1)
					aa->caps |= has_discfreq;	/* more than one frequency */
				else
					aa->caps |= onefreq;		/* only one frequency */
			}
			aa->nchan = b[4];
			aa->res = b[6];
			aa->subframesize = b[5];
			break;
		default:
			if (debug & Dbginfo)
				pcs_raw("audio stream unknown", bb, nb);
		}
		break;
	case 3: // midi
	default:
		if (debug & Dbginfo){
			fprint(2, "Unknown audio stream type: ");
			pcs_raw("CS_INTERFACE", bb, nb);
		}
	}
}