project64/Source/Project64-rsp/dma.cpp

#include <stdint.h>
#include <stdio.h>
#include <string.h>

#include "RSP Registers.h"
#include "Rsp.h"
#include "memory.h"

// #define RSP_SAFE_DMA // Unoptimized DMA transfers

void SP_DMA_READ(void)
{
    uint32_t i, j, Length, Skip, Count, End, addr;
    uint8_t *Dest, *Source;

    addr = (*RSPInfo.SP_DRAM_ADDR_REG) & 0x00FFFFFF;

    if (addr > 0x7FFFFF)
    {
        DisplayError("SP DMA READ\nSP_DRAM_ADDR_REG not in RDRAM space");
        return;
    }

    if ((*RSPInfo.SP_RD_LEN_REG & 0xFFF) + 1 + (*RSPInfo.SP_MEM_ADDR_REG & 0xFFF) > 0x1000)
    {
        DisplayError("SP DMA READ\nCould not fit copy in memory segment");
        return;
    }

    Length = ((*RSPInfo.SP_RD_LEN_REG & 0xFFF) | 7) + 1;
    Skip = (*RSPInfo.SP_RD_LEN_REG >> 20) + Length;
    Count = ((*RSPInfo.SP_RD_LEN_REG >> 12) & 0xFF) + 1;
    End = ((*RSPInfo.SP_MEM_ADDR_REG & 0x0FFF) & ~7) + (((Count - 1) * Skip) + Length);
    Dest = ((*RSPInfo.SP_MEM_ADDR_REG & 0x1000) != 0 ? RSPInfo.IMEM : RSPInfo.DMEM) + ((*RSPInfo.SP_MEM_ADDR_REG & 0x0FFF) & ~7);
    Source = RSPInfo.RDRAM + (addr & ~7);

#if defined(RSP_SAFE_DMA)
    for (j = 0; j < Count; j++)
    {
        for (i = 0; i < Length; i++)
        {
            *(uint8_t *)(((size_t)Dest + j * Length + i) ^ 3) = *(uint8_t *)(((size_t)Source + j * Skip + i) ^ 3);
        }
    }
#else
    if ((Skip & 0x3) == 0)
    {
        for (j = 0; j < Count; j++)
        {
            memcpy(Dest, Source, Length);
            Source += Skip;
            Dest += Length;
        }
    }
    else
    {
        for (j = 0; j < Count; j++)
        {
            for (i = 0; i < Length; i++)
            {
                *(uint8_t *)(((size_t)Dest + i) ^ 3) = *(uint8_t *)(((size_t)Source + i) ^ 3);
            }
            Source += Skip;
            Dest += Length;
        }
    }
#endif

    // TODO: Could this be a problem DMEM to IMEM?
    if (CPUCore == RecompilerCPU && (*RSPInfo.SP_MEM_ADDR_REG & 0x1000) != 0)
    {
        SetJumpTable(End);
    }

    *RSPInfo.SP_DMA_BUSY_REG = 0;
    *RSPInfo.SP_STATUS_REG &= ~SP_STATUS_DMA_BUSY;
}

void SP_DMA_WRITE(void)
{
    uint32_t i, j, Length, Skip, Count, addr;
    uint8_t *Dest, *Source;

    addr = (*RSPInfo.SP_DRAM_ADDR_REG) & 0x00FFFFFF;

    if (addr > 0x7FFFFF)
    {
        DisplayError("SP DMA WRITE\nSP_DRAM_ADDR_REG not in RDRAM space");
        return;
    }

    if ((*RSPInfo.SP_WR_LEN_REG & 0xFFF) + 1 + (*RSPInfo.SP_MEM_ADDR_REG & 0xFFF) > 0x1000)
    {
        DisplayError("SP DMA WRITE\nCould not fit copy in memory segment");
        return;
    }

    Length = ((*RSPInfo.SP_WR_LEN_REG & 0xFFF) | 7) + 1;
    Skip = (*RSPInfo.SP_WR_LEN_REG >> 20) + Length;
    Count = ((*RSPInfo.SP_WR_LEN_REG >> 12) & 0xFF) + 1;
    Dest = RSPInfo.RDRAM + (addr & ~7);
    Source = ((*RSPInfo.SP_MEM_ADDR_REG & 0x1000) != 0 ? RSPInfo.IMEM : RSPInfo.DMEM) + ((*RSPInfo.SP_MEM_ADDR_REG & 0xFFF) & ~7);

#if defined(RSP_SAFE_DMA)
    for (j = 0; j < Count; j++)
    {
        for (i = 0; i < Length; i++)
        {
            *(uint8_t *)(((size_t)Dest + j * Skip + i) ^ 3) = *(uint8_t *)(((size_t)Source + j * Length + i) ^ 3);
        }
    }
#else
    if ((Skip & 0x3) == 0)
    {
        for (j = 0; j < Count; j++)
        {
            memcpy(Dest, Source, Length);
            Source += Length;
            Dest += Skip;
        }
    }
    else
    {
        for (j = 0; j < Count; j++)
        {
            for (i = 0; i < Length; i++)
            {
                *(uint8_t *)(((size_t)Dest + i) ^ 3) = *(uint8_t *)(((size_t)Source + i) ^ 3);
            }
            Source += Length;
            Dest += Skip;
        }
    }
#endif
    *RSPInfo.SP_DMA_BUSY_REG = 0;
    *RSPInfo.SP_STATUS_REG &= ~SP_STATUS_DMA_BUSY;
}