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#include "PR/rcp.h"
#include "PR/ultraerror.h"
#include "PRinternal/osint.h"
// TODO: not sure if this should be here
extern s32 osViClock;
// TODO: this comes from a header
#ident "$Revision: 1.17 $"
/**
* Programs the operating frequency of the Audio DAC.
*
* @param frequency Target Playback frequency.
* @return The actual playback frequency, or -1 if the supplied frequency cannot be used.
*/
s32 osAiSetFrequency(u32 frequency) {
register unsigned int dacRate;
register unsigned char bitRate;
register float f;
#ifdef _DEBUG
if (osViClock == VI_PAL_CLOCK) {
if (frequency < AI_PAL_MIN_FREQ || frequency > AI_PAL_MAX_FREQ) {
__osError(ERR_OSAISETFREQUENCY, 3, AI_PAL_MIN_FREQ, AI_PAL_MAX_FREQ, frequency);
return -1;
}
} else if (osViClock == VI_MPAL_CLOCK) {
if (frequency < AI_MPAL_MIN_FREQ || frequency > AI_MPAL_MAX_FREQ) {
__osError(ERR_OSAISETFREQUENCY, 3, AI_MPAL_MIN_FREQ, AI_MPAL_MAX_FREQ, frequency);
return -1;
}
} else {
if (frequency < AI_NTSC_MIN_FREQ || frequency > AI_NTSC_MAX_FREQ) {
__osError(ERR_OSAISETFREQUENCY, 3, AI_NTSC_MIN_FREQ, AI_NTSC_MAX_FREQ, frequency);
return -1;
}
}
#endif
// Calculate the DAC sample period ("dperiod") (dperiod + 1 = vid_clock / frequency)
f = osViClock / (float)frequency + .5f;
dacRate = f;
// Upcoming division by 66. If dacRate is smaller than 2 * 66 = 132, bitrate will be 1 and AI_BITRATE_REG will be
// programmed with 0, which results in no audio output. Return -1 to indicate an unusable frequency.
if (dacRate < AI_MIN_DAC_RATE) {
return -1;
}
// Calculate the largest "bitrate" (ABUS clock half period, "aclockhp") supported for this dacrate. These two
// quantities must satisfy (dperiod + 1) >= 66 * (aclockhp + 1), here this is taken as equality.
bitRate = dacRate / 66;
// Clamp to max value
if (bitRate > AI_MAX_BIT_RATE) {
bitRate = AI_MAX_BIT_RATE;
}
IO_WRITE(AI_DACRATE_REG, dacRate - 1);
IO_WRITE(AI_BITRATE_REG, bitRate - 1);
#if BUILD_VERSION < VERSION_J
IO_WRITE(AI_CONTROL_REG, AI_CONTROL_DMA_ON);
#endif
// Return the true playback frequency (frequency = vid_clock / (dperiod + 1)), which may differ from the target
// frequency.
return osViClock / (s32)dacRate;
}
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