md, improve z80/68k synchronization

diff --git a/pico/memory.c b/pico/memory.c
index 7462829..3267a16 100644 (file)
--- a/pico/memory.c
+++ b/pico/memory.c
@@ -1334,12 +1334,22 @@ void PicoWrite16_32x(u32 a, u32 d) {}
 // -----------------------------------------------------------------\r
 //                        z80 memhandlers\r
 \r
+static void access_68k_bus(int delay) // bus delay as Q8\r
+{\r
+  // 68k bus access delay for z80. The fractional part needs to be accumulated\r
+  // until an additional cycle is full. That is then added to the integer part.\r
+  Pico.t.z80_busdelay = (delay&0xff) + (Pico.t.z80_busdelay&0xff); // accumulate\r
+  z80_subCLeft((delay>>8) + (Pico.t.z80_busdelay>>8));\r
+  // don't use SekCyclesBurn(7) here since the Z80 doesn't run in cycle lock to\r
+  // the 68K. Count the stolen cycles to be accounted later in the 68k CPU runs\r
+  Pico.t.z80_buscycles += 7;\r
+}\r
+\r
 static unsigned char z80_md_vdp_read(unsigned short a)\r
 {\r
   if ((a & 0xff00) == 0x7f00) {\r
-    static int f; f = (f&0xff) + 0x8c; // 0.6\r
-    z80_subCLeft(2+(f>>8)); // 3.3 per kabuto, but notaz' test implies 2.6 ?!?\r
-    Pico.t.z80_buscycles += 7;\r
+    // 68k bus access delay=3.3 per kabuto, for notaz picotest 2.4<=delay<2.55?\r
+    access_68k_bus(0x280); // Q8, picotest: 0x266(>=2.4) - 0x28b(<2.55)\r
 \r
     switch (a & 0x0d)\r
     {\r
@@ -1363,12 +1373,8 @@ static unsigned char z80_md_bank_read(unsigned short a)
   unsigned int addr68k;\r
   unsigned char ret;\r
 \r
-  // account for 68K bus access on both CPUs.\r
-  static int f; f = (f&0xff) + 0x4c; // 0.3\r
-  z80_subCLeft(3+(f>>8)); // 3.3 per kabuto\r
-  // don't use SekCyclesBurn(7) here since the Z80 doesn't run in cycle lock to\r
-  // the 68K. Count the stolen cycles to be accounted later in the 68k CPU runs\r
-  Pico.t.z80_buscycles += 7;\r
+  // 68k bus access delay=3.3 per kabuto, but for notaz picotest 3.0<delay<3.3\r
+  access_68k_bus(0x340); // // Q8, picotest: 0x301(>3.0)-0x34c(<3.3)\r
 \r
   addr68k = Pico.m.z80_bank68k << 15;\r
   addr68k |= a & 0x7fff;\r
@@ -1409,12 +1415,8 @@ static void z80_md_bank_write(unsigned int a, unsigned char data)
 {\r
   unsigned int addr68k;\r
 \r
-  // account for 68K bus access on both CPUs.\r
-  static int f; f = (f&0xff) + 0x4c; // 0.3\r
-  z80_subCLeft(3+(f>>8)); // 3.3 per kabuto\r
-  // don't use SekCyclesBurn(7) here since the Z80 doesn't run in cycle lock to\r
-  // the 68K. Count the stolen cycles to be accounted later in the 68K CPU runs\r
-  Pico.t.z80_buscycles += 7;\r
+  // 68k bus access delay=3.3 per kabuto, but for notaz picotest 3.0<delay<3.3\r
+  access_68k_bus(0x340); // // Q8, picotest: 0x301(>3.0)-0x34c(<3.3)\r
 \r
   addr68k = Pico.m.z80_bank68k << 15;\r
   addr68k += a & 0x7fff;\r

diff --git a/pico/pico_int.h b/pico/pico_int.h
index f6618b9..055f5ee 100644 (file)
--- a/pico/pico_int.h
+++ b/pico/pico_int.h
@@ -204,8 +204,8 @@ extern struct DrZ80 drZ80;
 #define z80_cyclesDone() \\r
   (Pico.t.z80c_aim - z80_cyclesLeft)\r
 \r
-// one line has 488 68K cycles and 228 Z80 cycles, 228/488*8192=3827\r
-#define cycles_68k_to_z80(x) ((x) * 3847 >> 13)\r
+// 68k clock = OSC/7, z80 clock = OSC/15, 68k:z80 ratio = 7/15*8192=3822.9\r
+#define cycles_68k_to_z80(x) ((x) * 3823 >> 13)\r
 \r
 // ----------------------- SH2 CPU -----------------------\r
 \r
@@ -449,6 +449,7 @@ struct PicoTiming
   unsigned int z80c_line_start;\r
   int z80_scanline;\r
   int z80_buscycles;\r
+  int z80_busdelay;\r
 \r
   int timer_a_next_oflow, timer_a_step; // in z80 cycles\r
   int timer_b_next_oflow, timer_b_step;\r