sm64/lib/src/osAiSetNextBuffer.c

54 lines
1.3 KiB
C

#include "libultra_internal.h"
#include "PR/rcp.h"
/**
* It is worth noting that a previous hardware bug has been fixed by a software
* patch in osAiSetNextBuffer. This bug occurred when the address of the end of the
* buffer specified by osAiSetNextBuffer was at a specific value. This value
* occurred when the following was true:
*
* (vaddr + nbytes) & 0x00003FFF == 0x00002000
*
* (when the buffer ends with address of lower 14 bits 0x2000) In this case, the
* DMA transfer does not complete successfully. This can cause clicks and pops in
* the audio output. This bug no longer requires special handling by the application
* because it is now patched by osAiSetNextBuffer.
*/
s32 osAiSetNextBuffer(void *buff, u32 len) {
static u8 hdwrBugFlag = 0;
char *bptr;
#ifdef VERSION_CN
if (__osAiDeviceBusy()) {
return -1;
}
#endif
bptr = buff;
if (hdwrBugFlag != 0) {
bptr -= 0x2000;
}
#ifdef VERSION_CN
if ((((uintptr_t) buff + len) & 0x1fff) == 0) {
#else
if ((((uintptr_t) buff + len) & 0x3fff) == 0x2000) {
#endif
hdwrBugFlag = 1;
} else {
hdwrBugFlag = 0;
}
#ifndef VERSION_CN
if (__osAiDeviceBusy()) {
return -1;
}
#endif
IO_WRITE(AI_DRAM_ADDR_REG, osVirtualToPhysical(bptr));
IO_WRITE(AI_LEN_REG, len);
return 0;
}