From 4c34e0a6e063ead12d89bb7e085e79d04702ba57 Mon Sep 17 00:00:00 2001
From: Lior Halphon <LIJI32@gmail.com>
Date: Sat, 1 Jun 2019 18:22:58 +0300
Subject: [PATCH] =?UTF-8?q?Turns=20out=20the=20AGB=20inverts=20Channel=203?=
 =?UTF-8?q?=E2=80=99s=20output?=
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---
 Core/apu.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/Core/apu.c b/Core/apu.c
index b4f4d752..d5537a6e 100644
--- a/Core/apu.c
+++ b/Core/apu.c
@@ -59,6 +59,11 @@ static void update_sample(GB_gameboy_t *gb, unsigned index, int8_t value, unsign
             unsigned right_volume = (gb->io_registers[GB_IO_NR50] & 7) + 1;
             unsigned left_volume = ((gb->io_registers[GB_IO_NR50] >> 4) & 7) + 1;
             
+            if (index == GB_WAVE) {
+                /* For some reason, channel 3 is inverted on the AGB */
+                value ^= 0xF;
+            }
+            
             GB_sample_t output;
             if (gb->io_registers[GB_IO_NR51] & (1 << index)) {
                 output.right = (0xf - value * 2) * right_volume;