1 files changed, 144 insertions, 0 deletions
diff --git a/DMA.cpp b/DMA.cpp
new file mode 100644
index 0000000..1b04c3a
--- /dev/null
+++ b/DMA.cpp
@@ -0,0 +1,144 @@
+/*
+    Copyright 2016-2017 StapleButter
+
+    This file is part of melonDS.
+
+    melonDS is free software: you can redistribute it and/or modify it under
+    the terms of the GNU General Public License as published by the Free
+    Software Foundation, either version 3 of the License, or (at your option)
+    any later version.
+
+    melonDS is distributed in the hope that it will be useful, but WITHOUT ANY
+    WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
+    FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details.
+
+    You should have received a copy of the GNU General Public License along
+    with melonDS. If not, see http://www.gnu.org/licenses/.
+*/
+
+#include <stdio.h>
+#include "NDS.h"
+#include "DMA.h"
+
+
+// NOTES ON DMA SHIT
+//
+// * could use optimized code paths for common types of DMA transfers. for example, VRAM
+// * needs to eventually be made more accurate anyway. DMA isn't instant.
+
+
+DMA::DMA(u32 cpu, u32 num)
+{
+    CPU = cpu;
+    Num = num;
+
+    Reset();
+}
+
+DMA::~DMA()
+{
+}
+
+void DMA::Reset()
+{
+    SrcAddr = 0;
+    DstAddr = 0;
+    Cnt = 0;
+
+    StartMode = 0;
+    CurSrcAddr = 0;
+    CurDstAddr = 0;
+    RemCount = 0;
+    SrcAddrInc = 0;
+    DstAddrInc = 0;
+}
+
+void DMA::WriteCnt(u32 val)
+{
+    u32 oldcnt = Cnt;
+    Cnt = val;
+
+    if ((!(oldcnt & 0x80000000)) && (val & 0x80000000))
+    {
+        CurSrcAddr = SrcAddr;
+        CurDstAddr = DstAddr;
+
+        switch (Cnt & 0x00060000)
+        {
+        case 0x00000000: DstAddrInc = 1; break;
+        case 0x00020000: DstAddrInc = -1; break;
+        case 0x00040000: DstAddrInc = 0; break;
+        case 0x00060000: DstAddrInc = 1; break;
+        }
+
+        switch (Cnt & 0x00180000)
+        {
+        case 0x00000000: SrcAddrInc = 1; break;
+        case 0x00080000: SrcAddrInc = -1; break;
+        case 0x00100000: SrcAddrInc = 0; break;
+        case 0x00180000: SrcAddrInc = 1; printf("BAD DMA SRC INC MODE 3\n"); break;
+        }
+
+        if (CPU == 0)
+            StartMode = (Cnt >> 27) & 0x7;
+        else
+            StartMode = ((Cnt >> 28) & 0x3) | 0x8;
+
+        if ((StartMode & 0x7) == 0)
+            Start();
+    }
+}
+
+void DMA::Start()
+{
+    u32 countmask;
+    if (CPU == 0)
+        countmask = 0x001FFFFF;
+    else
+        countmask = (Num==3 ? 0x0000FFFF : 0x00003FFF);
+
+    RemCount = Cnt & countmask;
+    if (!RemCount)
+        RemCount = countmask+1;
+
+    if ((Cnt & 0x00060000) == 0x00060000)
+        CurDstAddr = DstAddr;
+
+    printf("ARM%d DMA%d %08X->%08X %d units %dbit\n", CPU?7:9, Num, CurSrcAddr, CurDstAddr, RemCount, (Cnt & 0x04000000)?16:32);
+
+    // TODO: NOT MAKE THE DMA INSTANT!!
+    if (Cnt & 0x04000000)
+    {
+        u16 (*readfn)(u32) = CPU ? NDS::ARM7Read16 : NDS::ARM9Read16;
+        void (*writefn)(u32,u16) = CPU ? NDS::ARM7Write16 : NDS::ARM9Write16;
+
+        while (RemCount > 0)
+        {
+            writefn(CurDstAddr, readfn(CurSrcAddr));
+
+            CurSrcAddr += SrcAddrInc<<1;
+            CurDstAddr += DstAddrInc<<1;
+            RemCount--;
+        }
+    }
+    else
+    {
+        u32 (*readfn)(u32) = CPU ? NDS::ARM7Read32 : NDS::ARM9Read32;
+        void (*writefn)(u32,u32) = CPU ? NDS::ARM7Write32 : NDS::ARM9Write32;
+
+        while (RemCount > 0)
+        {
+            writefn(CurDstAddr, readfn(CurSrcAddr));
+
+            CurSrcAddr += SrcAddrInc<<2;
+            CurDstAddr += DstAddrInc<<2;
+            RemCount--;
+        }
+    }
+
+    if (!(Cnt & 0x02000000))
+        Cnt &= ~0x80000000;
+
+    if (Cnt & 0x40000000)
+        NDS::TriggerIRQ(CPU, NDS::IRQ_DMA0 + Num);
+}