sm64/lib/src/osAiSetNextBuffer.c
2019-10-05 15:08:05 -04:00

41 lines
1.1 KiB
C

#include "libultra_internal.h"
#include "osAi.h"
#include "hardware.h"
u8 D_80334820 = 0;
/**
* 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) {
u8 *sp1c = buff;
if (D_80334820 != 0) {
sp1c -= 0x2000;
}
if ((((uintptr_t) buff + len) & 0x3fff) == 0x2000) {
D_80334820 = 1;
} else {
D_80334820 = 0;
}
if (__osAiDeviceBusy()) {
return -1;
}
HW_REG(AI_DRAM_ADDR_REG, void *) = (void *) osVirtualToPhysical(sp1c);
HW_REG(AI_LEN_REG, u32) = len;
return 0;
}