Add FAST_ALIGNED_LSB_WORD_ACCESS optimization

From https://github.com/m45t3r/snes9x4d/commit/cf6dedb11f1062588d8c747d13c59e7c1d2fa233

2 files changed, 26 insertions, 1 deletions

diff --git a/src/cpuaddr.h b/src/cpuaddr.h
index d68a328..a9fc85a 100644
--- a/src/cpuaddr.h
+++ b/src/cpuaddr.h
@@ -145,6 +145,11 @@ static INLINE void AbsoluteLong()
 {

 #ifdef FAST_LSB_WORD_ACCESS

    OpAddress = (*(uint32*) CPU.PC) & 0xffffff;

+#elsif FAST_ALIGNED_LSB_WORD_ACCESS

+   if (((int32_t) CPU.PC & 1) == 0)

+		OpAddress = (*(uint16_t*) CPU.PC) + (CPU.PC[2] << 16);

+	else

+		OpAddress = *CPU.PC + ((*(uint16_t*) (CPU.PC + 1)) << 8);

 #else

    OpAddress = *CPU.PC + (*(CPU.PC + 1) << 8) + (*(CPU.PC + 2) << 16);

 #endif

@@ -272,6 +277,11 @@ static INLINE void AbsoluteLongIndexedX()
 {

 #ifdef FAST_LSB_WORD_ACCESS

    OpAddress = (*(uint32*) CPU.PC + Registers.X.W) & 0xffffff;

+#elsif FAST_ALIGNED_LSB_WORD_ACCESS

+   if (((int32_t) CPU.PC & 1) == 0)

+		OpAddress = ((*(uint16_t*) CPU.PC) + (CPU.PC[2] << 16) + reg->X.W) & 0xFFFFFF;

+	else

+		OpAddress = (*CPU.PC + ((*(uint16_t*) (CPU.PC + 1)) << 8) + reg->X.W) & 0xFFFFFF;

 #else

    OpAddress = (*CPU.PC + (*(CPU.PC + 1) << 8) + (*(CPU.PC + 2) << 16) + Registers.X.W) & 0xffffff;

 #endif

diff --git a/src/ppu.c b/src/ppu.c
index 31d1388..adc7046 100644
--- a/src/ppu.c
+++ b/src/ppu.c
@@ -257,9 +257,13 @@ void S9xSetCPU(uint8 byte, uint16 Address)
       {
          // Multiplicand
          uint32 res = Memory.FillRAM[0x4202] * byte;
-
+#if defined FAST_LSB_WORD_ACCESS || defined FAST_ALIGNED_LSB_WORD_ACCESS
+			/* assume malloc'd memory is 2-byte aligned */
+			*((uint16 *)&Memory.FillRAM[0x4216]) = res;
+#else
          Memory.FillRAM[0x4216] = (uint8) res;
          Memory.FillRAM[0x4217] = (uint8)(res >> 8);
+#endif
          break;
       }
       case 0x4204 :
@@ -269,15 +273,26 @@ void S9xSetCPU(uint8 byte, uint16 Address)
       case 0x4206 :
       {
          // Divisor
+#if defined FAST_LSB_WORD_ACCESS || defined FAST_ALIGNED_LSB_WORD_ACCESS
+			/* assume malloc'd memory is 2-byte aligned */
+			uint16 a = *((uint16 *)&Memory.FillRAM[0x4204]);
+#else
          uint16 a =
             Memory.FillRAM[0x4204] + (Memory.FillRAM[0x4205] << 8);
+#endif
          uint16 div = byte ? a / byte : 0xffff;
          uint16 rem = byte ? a % byte : a;
 
+#if defined FAST_LSB_WORD_ACCESS || defined FAST_ALIGNED_LSB_WORD_ACCESS
+			/* assume malloc'd memory is 2-byte aligned */
+			*((uint16 *)&Memory.FillRAM[0x4214]) = div;
+			*((uint16 *)&Memory.FillRAM[0x4216]) = rem;
+#else
          Memory.FillRAM[0x4214] = (uint8) div;
          Memory.FillRAM[0x4215] = div >> 8;
          Memory.FillRAM[0x4216] = (uint8) rem;
          Memory.FillRAM[0x4217] = rem >> 8;
+#endif
          break;
       }
       case 0x4207 :