oot/src/libultra_boot_O2/__osPiRawStartDma.c

#include <global.h>
#include <ultra64/hardware.h>

s32 __osPiRawStartDma(s32 dir, u32 cart_addr, void* dram_addr, size_t size) {
    register int status;
    status = HW_REG(PI_STATUS_REG, u32);
    while (status & (PI_STATUS_BUSY | PI_STATUS_IOBUSY | PI_STATUS_ERROR)) {
        status = HW_REG(PI_STATUS_REG, u32);
    }

    HW_REG(PI_DRAM_ADDR_REG, void*) = (void*)osVirtualToPhysical(dram_addr);

    HW_REG(PI_CART_ADDR_REG, void*) = (void*)((osRomBase | cart_addr) & 0x1fffffff);

    switch (dir) {
        case OS_READ:
            HW_REG(PI_WR_LEN_REG, u32) = size - 1;
            break;
        case OS_WRITE:
            HW_REG(PI_RD_LEN_REG, u32) = size - 1;
            break;
        default:
            return -1;
            break;
    }
    return 0;
}