From 8b1e490a551b2fe5e184aa9111f837d5b3a69bc7 Mon Sep 17 00:00:00 2001
From: João Silva
Date: Sat, 14 Jan 2017 19:45:43 +0000
Subject: Imported code from the speed-hacks branch.

---
 source/cpuops.c | 211 ++++++++++++++++++++++++++++++++++++++++++++++++++++++--
 1 file changed, 207 insertions(+), 4 deletions(-)

(limited to 'source/cpuops.c')

diff --git a/source/cpuops.c b/source/cpuops.c
index d7f90e6..977f97e 100644
--- a/source/cpuops.c
+++ b/source/cpuops.c
@@ -3424,6 +3424,31 @@ static inline void CPUShutdown()
 #define CPUShutdown()
 #endif
 
+// From the speed-hacks branch of CatSFC
+static inline void ForceShutdown()
+{
+#ifdef CPU_SHUTDOWN
+#ifndef SA1_OPCODES
+   CPU.WaitAddress = NULL;
+   if (Settings.SA1)
+      S9xSA1ExecuteDuringSleep ();
+   CPU.Cycles = CPU.NextEvent;
+   if (IAPU.APUExecuting)
+   {
+      ICPU.CPUExecuting = false;
+      do
+      {
+         APU_EXECUTE1();
+      } while (APU.Cycles < CPU.NextEvent);
+      ICPU.CPUExecuting = true;
+   }
+#else
+   SA1.Executing = false;
+   SA1.CPUExecuting = false;
+#endif
+#endif
+}
+
 /* BCC */
 static void Op90(void)
 {
@@ -5008,16 +5033,194 @@ static void OpCB(void)
 #endif // SA1_OPCODES
 }
 
-// STP
+// Usually an STP opcode
+// SNESAdvance speed hack, not implemented in Snes9xTYL | Snes9x-Euphoria (from the speed-hacks branch of CatSFC)
 static void OpDB(void)
 {
-   CPU.PC--;
-   CPU.Flags |= DEBUG_MODE_FLAG;
+#if !defined NO_SPEEDHACKS && defined CPU_SHUTDOWN
+   uint8_t NextByte = *CPU.PC++;
+
+   ForceShutdown();
+
+   int8_t BranchOffset = (NextByte & 0x7F) | ((NextByte & 0x40) << 1);
+   // ^ -64 .. +63, sign extend bit 6 into 7 for unpacking
+   long TargetAddress = ((int) (CPU.PC - CPU.PCBase) + BranchOffset) & 0xffff;
+
+   switch (NextByte & 0x80)
+   {
+   case 0x00: // BNE
+      BranchCheck1 ();
+      if (!CheckZero ()) {
+         CPU.PC = CPU.PCBase + TargetAddress;
+#ifdef VAR_CYCLES
+         CPU.Cycles += ONE_CYCLE;
+#else
+#ifndef SA1_OPCODES
+         CPU.Cycles++;
+#endif
+#endif
+         CPUShutdown ();
+      }
+      return;
+   case 0x80: // BEQ
+      BranchCheck2 ();
+      if (CheckZero ()) {
+         CPU.PC = CPU.PCBase + TargetAddress;
+#ifdef VAR_CYCLES
+         CPU.Cycles += ONE_CYCLE;
+#else
+#ifndef SA1_OPCODES
+         CPU.Cycles++;
+#endif
+#endif
+         CPUShutdown ();
+      }
+      return;
+   }
+#else
+     CPU.PC--;
+     CPU.Flags |= DEBUG_MODE_FLAG;
+#endif
 }
 
-// Reserved S9xOpcode
+// SNESAdvance speed hack, as implemented in Snes9xTYL / Snes9x-Euphoria (from the speed-hacks branch of CatSFC)
 static void Op42(void)
 {
+#if !defined NO_SPEEDHACKS && defined CPU_SHUTDOWN
+   uint8_t NextByte = *CPU.PC++;
+
+   ForceShutdown();
+
+   int8_t BranchOffset = 0xF0 | (NextByte & 0xF); // always negative
+   long TargetAddress = ((int) (CPU.PC - CPU.PCBase) + BranchOffset) & 0xffff;
+
+   switch (NextByte & 0xF0)
+   {
+   case 0x10: // BPL
+      BranchCheck1 ();
+      if (!CheckNegative ()) {
+         CPU.PC = CPU.PCBase + TargetAddress;
+#ifdef VAR_CYCLES
+         CPU.Cycles += ONE_CYCLE;
+#else
+#ifndef SA1_OPCODES
+         CPU.Cycles++;
+#endif
+#endif
+         CPUShutdown ();
+      }
+      return;
+   case 0x30: // BMI
+      BranchCheck1 ();
+      if (CheckNegative ()) {
+         CPU.PC = CPU.PCBase + TargetAddress;
+#ifdef VAR_CYCLES
+         CPU.Cycles += ONE_CYCLE;
+#else
+#ifndef SA1_OPCODES
+         CPU.Cycles++;
+#endif
+#endif
+         CPUShutdown ();
+      }
+      return;
+   case 0x50: // BVC
+      BranchCheck0 ();
+      if (!CheckOverflow ()) {
+         CPU.PC = CPU.PCBase + TargetAddress;
+#ifdef VAR_CYCLES
+         CPU.Cycles += ONE_CYCLE;
+#else
+#ifndef SA1_OPCODES
+         CPU.Cycles++;
+#endif
+#endif
+         CPUShutdown ();
+      }
+      return;
+   case 0x70: // BVS
+      BranchCheck0 ();
+      if (CheckOverflow ()) {
+         CPU.PC = CPU.PCBase + TargetAddress;
+#ifdef VAR_CYCLES
+         CPU.Cycles += ONE_CYCLE;
+#else
+#ifndef SA1_OPCODES
+         CPU.Cycles++;
+#endif
+#endif
+         CPUShutdown ();
+      }
+      return;
+   case 0x80: // BRA
+      CPU.PC = CPU.PCBase + TargetAddress;
+#ifdef VAR_CYCLES
+      CPU.Cycles += ONE_CYCLE;
+#else
+#ifndef SA1_OPCODES
+      CPU.Cycles++;
+#endif
+#endif
+      CPUShutdown ();
+      return;
+   case 0x90: // BCC
+      BranchCheck0 ();
+      if (!CheckCarry ()) {
+         CPU.PC = CPU.PCBase + TargetAddress;
+#ifdef VAR_CYCLES
+         CPU.Cycles += ONE_CYCLE;
+#else
+#ifndef SA1_OPCODES
+         CPU.Cycles++;
+#endif
+#endif
+         CPUShutdown ();
+      }
+      return;
+   case 0xB0: // BCS
+      BranchCheck0 ();
+      if (CheckCarry ()) {
+         CPU.PC = CPU.PCBase + TargetAddress;
+#ifdef VAR_CYCLES
+         CPU.Cycles += ONE_CYCLE;
+#else
+#ifndef SA1_OPCODES
+         CPU.Cycles++;
+#endif
+#endif
+         CPUShutdown ();
+      }
+      return;
+   case 0xD0: // BNE
+      BranchCheck1 ();
+      if (!CheckZero ()) {
+         CPU.PC = CPU.PCBase + TargetAddress;
+#ifdef VAR_CYCLES
+         CPU.Cycles += ONE_CYCLE;
+#else
+#ifndef SA1_OPCODES
+         CPU.Cycles++;
+#endif
+#endif
+         CPUShutdown ();
+      }
+      return;
+   case 0xF0: // BEQ
+      BranchCheck2 ();
+      if (CheckZero ()) {
+         CPU.PC = CPU.PCBase + TargetAddress;
+#ifdef VAR_CYCLES
+         CPU.Cycles += ONE_CYCLE;
+#else
+#ifndef SA1_OPCODES
+         CPU.Cycles++;
+#endif
+#endif
+         CPUShutdown ();
+      }
+      return;
+   }
+#endif
 }
 
 /*****************************************************************************/
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