From cd20f918cf1f7c7b3f63b61d64891d3b03cbe340 Mon Sep 17 00:00:00 2001
From: neonloop
Date: Fri, 12 Mar 2021 17:23:02 +0000
Subject: Add FAST_ALIGNED_LSB_WORD_ACCESS optimization

From https://github.com/m45t3r/snes9x4d/commit/cf6dedb11f1062588d8c747d13c59e7c1d2fa233
---
 src/cpuaddr.h | 10 ++++++++++
 src/ppu.c     | 17 ++++++++++++++++-
 2 files changed, 26 insertions(+), 1 deletion(-)

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 :
-- 
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