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audio: Improve use of the volatile keyword
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@JayFoxRox
JayFoxRox committed Jun 9, 2020
1 parent 94eb218 commit 0606d4e
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Showing 2 changed files with 39 additions and 28 deletions.
51 changes: 31 additions & 20 deletions lib/hal/audio.c
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Original file line number Diff line number Diff line change
Expand Up @@ -46,7 +46,7 @@ static void __stdcall DPC(PKDPC Dpc,
//CAUTION : if you use fpu in DPC you have to save & restore yourself fpu state!!!
//(fpu=floating point unit, i.e the coprocessor executing floating point opcodes)

volatile AC97_DEVICE *pac97device;
AC97_DEVICE *pac97device;

pac97device = &ac97Device;
if (pac97device)
Expand All @@ -61,8 +61,11 @@ static void __stdcall DPC(PKDPC Dpc,
// PCM actions, since S/PDIF is always spooling through the same buffer.
static BOOLEAN __stdcall ISR(PKINTERRUPT Interrupt, PVOID ServiceContext)
{
unsigned char analogInterrupt = *(volatile unsigned char *)0xFEC00116;
unsigned char digitalInterrupt = *(volatile unsigned char *)0xFEC00176;
AC97_DEVICE *pac97device = &ac97Device;
volatile unsigned char *pb = (unsigned char *)pac97device->mmio;

unsigned char analogInterrupt = pb[0x116];
unsigned char digitalInterrupt = pb[0x176];

bool waitCompleted = false;

Expand All @@ -80,7 +83,7 @@ static BOOLEAN __stdcall ISR(PKINTERRUPT Interrupt, PVOID ServiceContext)

analogDrained = analogInterrupt & 4;

*(volatile unsigned char *)0xFEC00116=0xFF; // clear all int sources
pb[0x116]=0xFF; // clear all int sources
}

if (digitalInterrupt) {
Expand All @@ -97,7 +100,7 @@ static BOOLEAN __stdcall ISR(PKINTERRUPT Interrupt, PVOID ServiceContext)

digitalDrained = digitalInterrupt & 4;

*(volatile unsigned char *)0xFEC00176=0xFF; // clear all int sources
pb[0x176]=0xFF; // clear all int sources
}


Expand Down Expand Up @@ -136,7 +139,7 @@ void XDumpAudioStatus()
// are 16 bits, 2 channels (stereo)
void XAudioInit(int sampleSizeInBits, int numChannels, XAudioCallback callback, void *data)
{
volatile AC97_DEVICE * pac97device = &ac97Device;
AC97_DEVICE * pac97device = &ac97Device;
KIRQL irql;
ULONG vector;

Expand All @@ -152,9 +155,17 @@ void XAudioInit(int sampleSizeInBits, int numChannels, XAudioCallback callback,
pac97device->sampleSizeInBits = sampleSizeInBits;
pac97device->numChannels = numChannels;

// initialise descriptors to all 0x00 (no samples)
memset((void *)&pac97device->pcmSpdifDescriptor[0], 0, sizeof(pac97device->pcmSpdifDescriptor));
memset((void *)&pac97device->pcmOutDescriptor[0], 0, sizeof(pac97device->pcmOutDescriptor));
volatile unsigned char *pb = (unsigned char *)pac97device->mmio;

// initialise descriptors to all zero (no samples)
for(unsigned int i = 0; i < 32; i++) {
pac97device->pcmSpdifDescriptor[i].bufferStartAddress = 0;
pac97device->pcmSpdifDescriptor[i].bufferLengthInSamples = 0;
pac97device->pcmSpdifDescriptor[i].bufferControl = 0;
pac97device->pcmOutDescriptor[i].bufferStartAddress = 0;
pac97device->pcmOutDescriptor[i].bufferLengthInSamples = 0;
pac97device->pcmOutDescriptor[i].bufferControl = 0;
}

// perform cold reset
pac97device->mmio[0x12C>>2] &= ~2;
Expand All @@ -168,18 +179,18 @@ void XAudioInit(int sampleSizeInBits, int numChannels, XAudioCallback callback,
;

// reset bus master registers for analog output
*(volatile unsigned char*)0xFEC0011B = (1 << 4) | (1 << 3) | (1 << 2) | (1 << 1);
while((*(volatile unsigned char*)0xFEC0011B) & (1 << 1))
pb[0x11B] = (1 << 4) | (1 << 3) | (1 << 2) | (1 << 1);
while(pb[0x11B] & (1 << 1))
;

// reset bus master registers for digital output
*(volatile unsigned char*)0xFEC0017B = (1 << 4) | (1 << 3) | (1 << 2) | (1 << 1);
while((*(volatile unsigned char*)0xFEC0017B) & (1 << 1))
pb[0x17B] = (1 << 4) | (1 << 3) | (1 << 2) | (1 << 1);
while(pb[0x17B] & (1 << 1))
;

// clear all interrupts
((unsigned char *)pac97device->mmio)[0x116] = 0xFF;
((unsigned char *)pac97device->mmio)[0x176] = 0xFF;
pb[0x116] = 0xFF;
pb[0x176] = 0xFF;

// tell the audio chip where it should look for the descriptors
unsigned int pcmAddress = (unsigned int)&pac97device->pcmOutDescriptor[0];
Expand Down Expand Up @@ -216,7 +227,7 @@ void XAudioInit(int sampleSizeInBits, int numChannels, XAudioCallback callback,
// tell the chip it is OK to play...
void XAudioPlay()
{
volatile AC97_DEVICE *pac97device = &ac97Device;
AC97_DEVICE *pac97device = &ac97Device;
volatile unsigned char *pb = (unsigned char *)pac97device->mmio;
pb[0x11B] = 0x1d; // PCM out - run, allow interrupts
pb[0x17B] = 0x1d; // PCM out - run, allow interrupts
Expand All @@ -225,7 +236,7 @@ void XAudioPlay()
// tell the chip it is paused.
void XAudioPause()
{
volatile AC97_DEVICE *pac97device = &ac97Device;
AC97_DEVICE *pac97device = &ac97Device;
volatile unsigned char *pb = (unsigned char *)pac97device->mmio;
pb[0x11B] = 0x1c; // PCM out - PAUSE, allow interrupts
pb[0x17B] = 0x1c; // PCM out - PAUSE, allow interrupts
Expand All @@ -238,7 +249,7 @@ void XAudioPause()
// chip doesn't run out of data
void XAudioProvideSamples(unsigned char *buffer, unsigned short bufferLength, int isFinal)
{
volatile AC97_DEVICE *pac97device = &ac97Device;
AC97_DEVICE *pac97device = &ac97Device;
volatile unsigned char *pb = (unsigned char *)pac97device->mmio;

unsigned short bufferControl = 0x8000;
Expand All @@ -251,13 +262,13 @@ void XAudioProvideSamples(unsigned char *buffer, unsigned short bufferLength, in
pac97device->pcmOutDescriptor[pac97device->nextDescriptor].bufferStartAddress = address;
pac97device->pcmOutDescriptor[pac97device->nextDescriptor].bufferLengthInSamples = wordCount;
pac97device->pcmOutDescriptor[pac97device->nextDescriptor].bufferControl = bufferControl;
pb[0x115] = (unsigned char)pac97device->nextDescriptor; // set last active descriptor
pb[0x115] = pac97device->nextDescriptor; // set last active descriptor
analogBufferCount++;

pac97device->pcmSpdifDescriptor[pac97device->nextDescriptor].bufferStartAddress = address;
pac97device->pcmSpdifDescriptor[pac97device->nextDescriptor].bufferLengthInSamples = wordCount;
pac97device->pcmSpdifDescriptor[pac97device->nextDescriptor].bufferControl = bufferControl;
pb[0x175] = (unsigned char)pac97device->nextDescriptor; // set last active descriptor
pb[0x175] = pac97device->nextDescriptor; // set last active descriptor
digitalBufferCount++;

// increment to the next buffer descriptor (rolling around to 0 once you get to 31)
Expand Down
16 changes: 8 additions & 8 deletions lib/hal/audio.h
View file
Original file line number Diff line number Diff line change
Expand Up @@ -21,14 +21,14 @@ typedef struct
// represents the current ac97 device
typedef struct
{
AC97_DESCRIPTOR pcmSpdifDescriptor[32];
AC97_DESCRIPTOR pcmOutDescriptor[32];
volatile unsigned int *mmio;
volatile unsigned int nextDescriptor;
XAudioCallback callback;
void *callbackData;
int sampleSizeInBits;
int numChannels;
volatile AC97_DESCRIPTOR pcmSpdifDescriptor[32];
volatile AC97_DESCRIPTOR pcmOutDescriptor[32];
volatile unsigned int *mmio;
unsigned char nextDescriptor;
XAudioCallback callback;
void *callbackData;
int sampleSizeInBits;
int numChannels;
} AC97_DEVICE __attribute__ ((aligned (8)));

// note that I currently ignore sampleSizeInBits and numChannels. They
Expand Down

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