From 49c8aa78d9e28562f8c5fd0ce90cc7ecde2b2bba Mon Sep 17 00:00:00 2001
From: notaz <notasas@gmail.com>
Date: Fri, 11 Aug 2017 02:12:57 +0300
Subject: [PATCH] drz80: drop fast_sp for compatibility

no measurable improvement in most cases anyway
---
 cpu/DrZ80/drz80.s |  4 +++-
 pico/z80if.c      | 19 +++++++++++++++++--
 2 files changed, 20 insertions(+), 3 deletions(-)

diff --git a/cpu/DrZ80/drz80.s b/cpu/DrZ80/drz80.s
index b92b2c2d..c2a64df3 100644
--- a/cpu/DrZ80/drz80.s
+++ b/cpu/DrZ80/drz80.s
@@ -12,7 +12,7 @@
       .global DrZ80Ver
 
       .equiv INTERRUPT_MODE,         0	;@0 = Use internal int handler, 1 = Use Mames int handler
-      .equiv FAST_Z80SP,             1	;@0 = Use mem functions for stack pointer, 1 = Use direct mem pointer
+      .equiv FAST_Z80SP,             0	;@0 = Use mem functions for stack pointer, 1 = Use direct mem pointer
       .equiv UPDATE_CONTEXT,         0
       .equiv DRZ80_XMAP,             1
       .equiv DRZ80_XMAP_MORE_INLINE, 1
@@ -212,6 +212,7 @@ z80_bad_jump:
     mov z80pc,r0
     ldmfd sp!,{r3,r12,pc}
 
+.if FAST_Z80SP
 z80_xmap_rebase_sp:
     ldr r1,[cpucontext,#z80_read8]
     sub r2,r0,#1
@@ -228,6 +229,7 @@ z80_xmap_rebase_sp:
     ldr pc,[cpucontext,#z80_rebaseSP]
     mov z80sp,r0
     ldmfd sp!,{r3,r12,pc}
+.endif @ FAST_Z80SP
  
 .endif @ DRZ80_XMAP
 
diff --git a/pico/z80if.c b/pico/z80if.c
index 5efeff89..33a86180 100644
--- a/pico/z80if.c
+++ b/pico/z80if.c
@@ -14,9 +14,11 @@ uptr z80_read_map [0x10000 >> Z80_MEM_SHIFT];
 uptr z80_write_map[0x10000 >> Z80_MEM_SHIFT];
 
 #ifdef _USE_DRZ80
-struct DrZ80 drZ80;
+// this causes trouble in some cases, like doukutsu putting sp in bank area
+// no perf difference for most, upto 1-2% for some others
+//#define FAST_Z80SP
 
-static u32 drz80_sp_base;
+struct DrZ80 drZ80;
 
 static void drz80_load_pcsp(u32 pc, u32 sp)
 {
@@ -28,6 +30,8 @@ static void drz80_load_pcsp(u32 pc, u32 sp)
     drZ80.Z80PC_BASE <<= 1;
     drZ80.Z80PC = drZ80.Z80PC_BASE + pc;
   }
+  drZ80.Z80SP = sp;
+#ifdef FAST_Z80SP
   drZ80.Z80SP_BASE = z80_read_map[sp >> Z80_MEM_SHIFT];
   if (drZ80.Z80SP_BASE & (1<<31)) {
     elprintf(EL_STATUS|EL_ANOMALY, "load_pcsp: bad SP: %04x", sp);
@@ -37,6 +41,7 @@ static void drz80_load_pcsp(u32 pc, u32 sp)
     drZ80.Z80SP_BASE <<= 1;
     drZ80.Z80SP = drZ80.Z80SP_BASE + sp;
   }
+#endif
 }
 
 // called only if internal xmap rebase fails
@@ -47,13 +52,19 @@ static unsigned int dz80_rebase_pc(unsigned short pc)
   return drZ80.Z80PC_BASE;
 }
 
+#ifdef FAST_Z80SP
+static u32 drz80_sp_base;
+
 static unsigned int dz80_rebase_sp(unsigned short sp)
 {
   elprintf(EL_STATUS|EL_ANOMALY, "dz80_rebase_sp: fail on %04x", sp);
   drZ80.Z80SP_BASE = z80_read_map[drz80_sp_base >> Z80_MEM_SHIFT] << 1;
   return drZ80.Z80SP_BASE + (1 << Z80_MEM_SHIFT) - 0x100;
 }
+#else
+#define dz80_rebase_sp NULL
 #endif
+#endif // _USE_DRZ80
 
 
 void z80_init(void)
@@ -91,9 +102,11 @@ void z80_reset(void)
   drZ80.Z80IX = 0xFFFF << 16;
   drZ80.Z80IY = 0xFFFF << 16;
 */
+#ifdef FAST_Z80SP
   // drZ80 is locked in single bank
   drz80_sp_base = (PicoAHW & PAHW_SMS) ? 0xc000 : 0x0000;
   drZ80.Z80SP_BASE = z80_read_map[drz80_sp_base >> Z80_MEM_SHIFT] << 1;
+#endif
   if (PicoAHW & PAHW_SMS)
     drZ80.Z80SP = drZ80.Z80SP_BASE + 0xdff0; // simulate BIOS
   // XXX: since we use direct SP pointer, it might make sense to force it to RAM,
@@ -286,3 +299,5 @@ void z80_debug(char *dstr)
   sprintf(dstr, "Z80 state: PC: %04x SP: %04x\n", (unsigned int)(CZ80.PC - CZ80.BasePC), CZ80.SP.W);
 #endif
 }
+
+// vim:ts=2:sw=2:expandtab
-- 
2.39.5