Various fixes for GPU/DSP DIV instruction, fixes for joypad handling.

[virtualjaguar] / src / dsp.cpp

diff --git a/src/dsp.cpp b/src/dsp.cpp
index 748c4ab01750a4f1c4a2bf509fe1a957fc701a1a..2dab23c2e6f90cf5cfd9f9df30555f47a1a578a9 100644 (file)
--- a/src/dsp.cpp
+++ b/src/dsp.cpp
@@ -2403,6 +2403,7 @@ static void dsp_opcode_abs(void)
 
 static void dsp_opcode_div(void)
 {
+#if 0
        uint32_t _Rm=RM;
        uint32_t _Rn=RN;
 
@@ -2425,6 +2426,32 @@ static void dsp_opcode_div(void)
        }
        else
                RN=0xffffffff;
+#else
+       if (RM)
+       {
+               if (dsp_div_control & 0x01)             // 16.16 division
+               {
+                       dsp_remain = ((uint64_t)RN << 16) % RM;
+                       RN = ((uint64_t)RN << 16) / RM;
+               }
+               else
+               {
+                       // We calculate the remainder first because we destroy RN after
+                       // this by assigning it to itself.
+                       dsp_remain = RN % RM;
+                       RN = RN / RM;
+               }
+
+// What we really should do here is figure out why this condition
+// happens in the real divide unit and emulate *that* behavior.
+#if 0
+               if ((gpu_remain - RM) & 0x80000000)     // If the result would have been negative...
+                       gpu_remain -= RM;                       // Then make it negative!
+#endif
+       }
+       else
+               RN = 0xFFFFFFFF;
+#endif
 }
 
 static void dsp_opcode_imultn(void)