From eef77d7a8b0b0d47e9559e40d8cb6407ea39b0f2 Mon Sep 17 00:00:00 2001
From: notaz <notasas@gmail.com>
Date: Sat, 21 Oct 2017 00:02:38 +0300
Subject: [PATCH] handle 'bad' dma better

---
 pico/pico.c      |  5 ++---
 pico/videoport.c | 14 +++++++++-----
 2 files changed, 11 insertions(+), 8 deletions(-)

diff --git a/pico/pico.c b/pico/pico.c
index 2e561c6..76c5fe9 100644
--- a/pico/pico.c
+++ b/pico/pico.c
@@ -253,10 +253,9 @@ PICO_INTERNAL int CheckDMA(void)
   xfers_can = dma_timings[dma_op];
   if(xfers <= xfers_can)
   {
-    if(dma_op&2) Pico.video.status&=~2; // dma no longer busy
-    else {
+    Pico.video.status &= ~SR_DMA;
+    if (!(dma_op & 2))
       burn = xfers * dma_bsycles[dma_op] >> 8; // have to be approximate because can't afford division..
-    }
     Pico.m.dma_xfers = 0;
   } else {
     if(!(dma_op&2)) burn = 488;
diff --git a/pico/videoport.c b/pico/videoport.c
index 355489e..9def819 100644
--- a/pico/videoport.c
+++ b/pico/videoport.c
@@ -100,7 +100,7 @@ static void DmaSlow(int len, unsigned int source)
     Pico.video.type, source, a, len, inc, (Pico.video.status&8)||!(Pico.video.reg[1]&0x40),
     SekCyclesDone(), SekPc);
 
-  Pico.m.dma_xfers += len;
+  Pico.m.dma_xfers = len;
   if (Pico.m.dma_xfers < len) // lame 16bit var
     Pico.m.dma_xfers = ~0;
   SekCyclesBurnRun(CheckDMA());
@@ -225,10 +225,10 @@ static void DmaCopy(int len)
   int source;
   elprintf(EL_VDPDMA, "DmaCopy len %i [%u]", len, SekCyclesDone());
 
-  Pico.m.dma_xfers += len;
+  Pico.m.dma_xfers = len;
   if (Pico.m.dma_xfers < len)
     Pico.m.dma_xfers = ~0;
-  Pico.video.status |= 2; // dma busy
+  Pico.video.status |= SR_DMA;
 
   source =Pico.video.reg[0x15];
   source|=Pico.video.reg[0x16]<<8;
@@ -256,10 +256,10 @@ static NOINLINE void DmaFill(int data)
   len = GetDmaLength();
   elprintf(EL_VDPDMA, "DmaFill len %i inc %i [%u]", len, inc, SekCyclesDone());
 
-  Pico.m.dma_xfers += len;
+  Pico.m.dma_xfers = len;
   if (Pico.m.dma_xfers < len) // lame 16bit var
     Pico.m.dma_xfers = ~0;
-  Pico.video.status |= 2; // dma busy
+  Pico.video.status |= SR_DMA;
 
   switch (Pico.video.type)
   {
@@ -306,6 +306,10 @@ static NOINLINE void CommandDma(void)
 
   if ((pvid->reg[1]&0x10)==0) return; // DMA not enabled
 
+  if (Pico.m.dma_xfers)
+    elprintf(EL_VDPDMA|EL_ANOMALY, "Dma overlap, left=%d @ %06x",
+             Pico.m.dma_xfers, SekPc);
+
   len = GetDmaLength();
   source =Pico.video.reg[0x15];
   source|=Pico.video.reg[0x16] << 8;
-- 
2.39.2