git.y1.nz

commit 9bf7e0b4dffc20941e4dfadffc6899ae19463844
parent 95773b9538b5b85de95bdc06ab568b1a833386f0
Author: Lior Halphon <LIJI32@gmail.com>
Date:   Sun, 14 Aug 2022 17:43:28 +0300

More accurate sample repeat glitch, fixes #483

Diffstat:
M
Core/apu.c
21
++++-----------------

1 file changed, 4 insertions(+), 17 deletions(-)
diff --git a/Core/apu.c b/Core/apu.c
@@ -1111,19 +1111,6 @@ void GB_apu_write(GB_gameboy_t *gb, uint8_t reg, uint8_t value)
         case GB_IO_NR13:
         case GB_IO_NR23: {
             unsigned index = reg == GB_IO_NR23? GB_SQUARE_2: GB_SQUARE_1;
-            if (gb->apu.is_active[index]) {
-                /* On an AGB, as well as on CGB C and earlier (TODO: Tested: 0, B and C), it behaves slightly different on
-                 double speed. */
-                if (gb->model == GB_MODEL_CGB_E || gb->model == GB_MODEL_CGB_D || gb->apu.square_channels[index].sample_countdown & 1) {
-                    if (gb->apu.square_channels[index].did_tick &&
-                        gb->apu.square_channels[index].sample_countdown >> 1 == (gb->apu.square_channels[index].sample_length ^ 0x7FF)) {
-                        gb->apu.square_channels[index].current_sample_index--;
-                        gb->apu.square_channels[index].current_sample_index &= 7;
-                        gb->apu.square_channels[index].sample_surpressed = false;
-                    }
-                }
-            }
-            
             gb->apu.square_channels[index].sample_length &= ~0xFF;
             gb->apu.square_channels[index].sample_length |= value & 0xFF;
             break;
@@ -1133,10 +1120,10 @@ void GB_apu_write(GB_gameboy_t *gb, uint8_t reg, uint8_t value)
         case GB_IO_NR24: {
             unsigned index = reg == GB_IO_NR24? GB_SQUARE_2: GB_SQUARE_1;
             bool was_active = gb->apu.is_active[index];
-            /* TODO: When the sample length changes right before being updated, the countdown should change to the
-                     old length, but the current sample should not change. Because our write timing isn't accurate to
-                     the T-cycle, we hack around it by stepping the sample index backwards. */
-            if ((value & 0x80) == 0 && gb->apu.is_active[index]) {
+            /* TODO: When the sample length changes right before being updated from ≥$700 to <$700, the countdown
+                     should change to the old length, but the current sample should not change. Because our write
+                     timing isn't accurate to the T-cycle, we hack around it by stepping the sample index backwards. */
+            if ((value & 0x80) == 0 && gb->apu.is_active[index] && (gb->io_registers[reg] & 0x7) == 7 && (value & 7) != 7) {
                 /* On an AGB, as well as on CGB C and earlier (TODO: Tested: 0, B and C), it behaves slightly different on
                    double speed. */
                 if (gb->model == GB_MODEL_CGB_E || gb->model == GB_MODEL_CGB_D || gb->apu.square_channels[index].sample_countdown & 1) {

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