git.y1.nz

commit 71c6fa45e0ddb386ce6848fb05c5a972d449c9f2
parent a13469c4e2c97873be4725e18074f09ea3ab048f
Author: Lior Halphon <LIJI32@gmail.com>
Date:   Fri, 26 Feb 2021 00:40:18 +0200

Accurate RTC emulation

Diffstat:
M
Core/memory.c
8
+++++++-
M
Core/timing.c
6
++++++

2 files changed, 13 insertions(+), 1 deletion(-)
diff --git a/Core/memory.c b/Core/memory.c
@@ -192,7 +192,10 @@ static uint8_t read_mbc_ram(GB_gameboy_t *gb, uint16_t addr)
     if (gb->cartridge_type->has_rtc && gb->cartridge_type->mbc_type != GB_HUC3 &&
         gb->mbc3_rtc_mapped && gb->mbc_ram_bank <= 4) {
         /* RTC read */
-        gb->rtc_latched.high |= ~0xC1; /* Not all bytes in RTC high are used. */
+        gb->rtc_latched.seconds &= 0x3F;
+        gb->rtc_latched.minutes &= 0x3F;
+        gb->rtc_latched.hours &= 0x1F;
+        gb->rtc_latched.high &= 0xC1;
         return gb->rtc_latched.data[gb->mbc_ram_bank];
     }
 
@@ -693,6 +696,9 @@ static void write_mbc_ram(GB_gameboy_t *gb, uint16_t addr, uint8_t value)
     }
 
     if (gb->cartridge_type->has_rtc && gb->mbc3_rtc_mapped && gb->mbc_ram_bank <= 4) {
+        if (gb->mbc_ram_bank == 0) {
+            gb->rtc_cycles = 0;
+        }
         gb->rtc_latched.data[gb->mbc_ram_bank] = gb->rtc_real.data[gb->mbc_ram_bank] = value;
         return;
     }
diff --git a/Core/timing.c b/Core/timing.c
@@ -254,6 +254,10 @@ static void GB_rtc_run(GB_gameboy_t *gb, uint8_t cycles)
             current_time = time(NULL);
             break;
         case GB_RTC_MODE_ACCURATE:
+            if (gb->cartridge_type->mbc_type != GB_HUC3 && (gb->rtc_real.high & 0x40)) {
+                gb->rtc_cycles -= cycles;
+                return;
+            }
             if (gb->rtc_cycles < GB_get_unmultiplied_clock_rate(gb) * 2) return;
             gb->rtc_cycles -= GB_get_unmultiplied_clock_rate(gb) * 2;
             current_time = gb->last_rtc_second + 1;
@@ -299,6 +303,8 @@ static void GB_rtc_run(GB_gameboy_t *gb, uint8_t cycles)
             if (gb->rtc_real.high & 1) { /* Bit 8 of days*/
                 gb->rtc_real.high |= 0x80; /* Overflow bit */
             }
+            
+            gb->rtc_real.high ^= 1;
         }
     }
 }

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