[Core/CD] improved accuracy of CDC data transfer to Main-CPU and Sub-CPU when writing to CDC data register (verified on real hardware, cf. Krikzz's mcd-verificator)

2024-12-26 03:01:50 +01:00 · 2024-01-22 01:02:42 +01:00 · 2024-01-22 01:02:42 +01:00 · 64d3e08e7d
commit 64d3e08e7d
parent 2c1a2d0def
5 changed files with 14 additions and 0 deletions
--- a/builds/genesis_plus_gx_libretro.dll
+++ b/builds/genesis_plus_gx_libretro.dll
--- a/builds/genplus_cube.dol
+++ b/builds/genplus_cube.dol
--- a/builds/genplus_wii.dol
+++ b/builds/genplus_wii.dol
--- a/core/cd_hw/scd.c
+++ b/core/cd_hw/scd.c
@ -1405,6 +1405,13 @@ static void scd_write_word(unsigned int address, unsigned int data)
      return;
    }

+    case 0x08: /* CDC host data */
+    {
+      /* CDC data is also read (although unused) on write access (verified on real hardware, cf. Krikzz's mcd-verificator) */
+      cdc_host_r(CDC_SUB_CPU_ACCESS);
+      return;
+    }
+
    case 0x0c: /* Stopwatch (word access only) */
    {
      /* synchronize the counter with SUB-CPU */
--- a/core/mem68k.c
+++ b/core/mem68k.c
@ -1261,6 +1261,13 @@ void ctrl_io_write_word(unsigned int address, unsigned int data)
            return;
          }

+          case 0x08: /* CDC host data */
+          {
+            /* CDC data is also read (although unused) on write access (verified on real hardware, cf. Krikzz's mcd-verificator) */
+            cdc_host_r(CDC_MAIN_CPU_ACCESS);
+            return;
+          }
+
          case 0x0e:  /* CPU communication flags */
          {
            m68k_poll_sync(1<<0x0e);