PCjr: Correctly implement wait states, fixes #3140.

src/86box.c

@@ -224,6 +224,8 @@ int      other_ide_present = 0;                                   /* IDE control
 int      other_scsi_present = 0;                                  /* SCSI controllers from non-SCSI cards are
                                                                      present */
 
+int      is_pcjr = 0;                                             /* The current machine is PCjr. */
+
 // Accelerator key array
 struct accelKey acc_keys[NUM_ACCELS];
 

src/game/gameport.c

@@ -252,7 +252,7 @@ gameport_write(UNUSED(uint16_t addr), UNUSED(uint8_t val), void *priv)
     /* Notify the interface. */
     joystick->intf->write(joystick->dat);
 
-    cycles -= ISA_CYCLES(8);
+    cycles -= ISA_CYCLES((8 << is_pcjr));
 }
 
 static uint8_t
@@ -268,7 +268,7 @@ gameport_read(UNUSED(uint16_t addr), void *priv)
     /* Merge axis state with button state. */
     uint8_t ret = joystick->state | joystick->intf->read(joystick->dat);
 
-    cycles -= ISA_CYCLES(8);
+    cycles -= ISA_CYCLES((8 << is_pcjr));
 
     return ret;
 }

src/include/86box/86box.h

@@ -157,6 +157,7 @@ extern int      enable_discord;             /* (C) enable Discord integration */
 extern int      force_10ms;                 /* (C) force 10ms CPU frame interval */
 extern int      other_ide_present;          /* IDE controllers from non-IDE cards are present */
 extern int      other_scsi_present;         /* SCSI controllers from non-SCSI cards are present */
+extern int      is_pcjr;                    /* The current machine is PCjr. */
 
 extern int    hard_reset_pending;
 extern int    fixed_size_x;

src/include/86box/mem.h

@@ -483,6 +483,8 @@ extern void mem_remap_top_nomid(int kb);
 
 extern void umc_smram_recalc(uint32_t start, int set);
 
+extern void pcjr_waitstates(void *);
+
 extern mem_mapping_t *read_mapping[MEM_MAPPINGS_NO];
 extern mem_mapping_t *write_mapping[MEM_MAPPINGS_NO];
 

src/machine/m_pcjr.c

@@ -829,6 +829,8 @@ machine_pcjr_init(UNUSED(const machine_t *model))
 
     pcjr = calloc(1, sizeof(pcjr_t));
 
+    is_pcjr = 1;
+
     pic_init_pcjr();
     pit_common_init(0, pit_irq0_timer_pcjr, NULL);
 

src/machine/machine.c

@@ -123,6 +123,8 @@ machine_init_ex(int m)
         pci_flags = 0x00000000;
     }
 
+    is_pcjr = 0;
+
     /* All good, boot the machine! */
     if (machines[m].init)
         ret = machines[m].init(&machines[m]);

src/mem/mem.c

@@ -1840,6 +1840,9 @@ mem_read_ram(uint32_t addr, UNUSED(void *priv))
         mem_log("Read  B       %02X from %08X\n", ram[addr], addr);
 #endif
 
+    if (is_pcjr)
+        pcjr_waitstates(NULL);
+
     if (cpu_use_exec)
         addreadlookup(mem_logical_addr, addr);
 
@@ -2100,6 +2103,9 @@ mem_write_ram(uint32_t addr, uint8_t val, UNUSED(void *priv))
     if ((addr >= 0xa0000) && (addr <= 0xbffff))
         mem_log("Write B       %02X to   %08X\n", val, addr);
 #endif
+    if (is_pcjr)
+        pcjr_waitstates(NULL);
+
     if (cpu_use_exec) {
         addwritelookup(mem_logical_addr, addr);
         mem_write_ramb_page(addr, val, &pages[addr >> 12]);

src/video/vid_pcjr.c

@@ -35,6 +35,8 @@
 #include <86box/video.h>
 #include <86box/vid_cga.h>
 #include <86box/vid_cga_comp.h>
+#include <86box/plat_unused.h>
+#include "cpu.h"
 
 #include <86box/m_pcjr.h>
 
@@ -194,6 +196,16 @@ vid_in(uint16_t addr, void *priv)
     return ret;
 }
 
+void
+pcjr_waitstates(UNUSED(void *priv))
+{
+    int ws_array[16] = { 0, 1, 1, 1, 2, 2, 2, 3, 3, 3, 4, 4, 4, 5, 5, 5 };
+    int ws;
+
+    ws = ws_array[cycles & 0xf];
+    cycles -= ws;
+}
+
 static void
 vid_write(uint32_t addr, uint8_t val, void *priv)
 {
@@ -202,6 +214,8 @@ vid_write(uint32_t addr, uint8_t val, void *priv)
     if (pcjr->memctrl == -1)
         return;
 
+    pcjr_waitstates(NULL);
+
     pcjr->b8000[addr & 0x3fff] = val;
 }
 
@@ -213,6 +227,8 @@ vid_read(uint32_t addr, void *priv)
     if (pcjr->memctrl == -1)
         return 0xff;
 
+    pcjr_waitstates(NULL);
+
     return (pcjr->b8000[addr & 0x3fff]);
 }