Normalize invalid weekdays only after a $11 command
@@ -192,9 +192,20 @@ static uint8_t read_mbc_ram(GB_gameboy_t *gb, uint16_t addr)
break; // Read RAM
case 5:
switch (addr & 3) {
- case 0: return (((gb->rtc_latched.high & 7) << 8) + gb->rtc_latched.days) / 7; // Week count
- case 1: return gb->rtc_latched.hours |
- (((((gb->rtc_latched.high & 7) << 8) + gb->rtc_latched.days) % 7) << 5); // Hours and weekday
+ case 0: { // Week count
+ unsigned total_days = (((gb->rtc_latched.high & 7) << 8) + gb->rtc_latched.days);
+ if (gb->rtc_latched.high & 0x20) {
+ return total_days / 7 - 1;
+ }
+ return total_days / 7;
+ }
+ case 1: { // Week count
+ unsigned total_days = (((gb->rtc_latched.high & 7) << 8) + gb->rtc_latched.days);
+ if (gb->rtc_latched.high & 0x20) {
+ return gb->rtc_latched.hours | 0xe0; // Hours and weekday
+ }
+ return gb->rtc_latched.hours | ((total_days % 7) << 5); // Hours and weekday
+ }
case 2: return gb->rtc_latched.minutes;
case 3: return gb->rtc_latched.seconds;
}
@@ -616,7 +627,7 @@ static void write_mbc(GB_gameboy_t *gb, uint16_t addr, uint8_t value)
case 0x11: {
uint8_t flags = gb->rtc_real.high & 0xc0;
memcpy(&gb->rtc_real, &gb->rtc_latched, sizeof(gb->rtc_real));
- gb->rtc_real.high &= ~0xc0;
+ gb->rtc_real.high &= ~0xe0;
gb->rtc_real.high |= flags;
break;
}
@@ -762,8 +773,12 @@ static void write_mbc_ram(GB_gameboy_t *gb, uint16_t addr, uint8_t value)
case 0: {
unsigned total_days = (((gb->rtc_latched.high & 7) << 8) + gb->rtc_latched.days);
total_days = total_days % 7 + value * 7;
+ bool had_illegal_weekday = gb->rtc_latched.high & 0x20;
gb->rtc_latched.days = total_days;
gb->rtc_latched.high = total_days >> 8;
+ if (had_illegal_weekday) {
+ gb->rtc_latched.high |= 0x20;
+ }
return;
}
case 1: {
@@ -772,6 +787,9 @@ static void write_mbc_ram(GB_gameboy_t *gb, uint16_t addr, uint8_t value)
gb->rtc_latched.hours = value & 0x1F;
gb->rtc_latched.days = total_days;
gb->rtc_latched.high = total_days >> 8;
+ if ((value & 0xE0) == 0xE0) { // Illegal weekday
+ gb->rtc_latched.high |= 0x20;
+ }
return;
}
case 2: gb->rtc_latched.minutes = value; return;
