CgbSound is decompiled.

1 files changed, 324 insertions, 0 deletions

diff --git a/src/m4a_3.c b/src/m4a_3.c
new file mode 100644
index 000000000..77d0087c0
--- /dev/null
+++ b/src/m4a_3.c
@@ -0,0 +1,324 @@
+#include "gba/m4a_internal.h"
+
+extern const u8 gCgb3Vol[];
+
+void CgbSound(void)
+{
+    s32 ch;
+    struct CgbChannel *channels;
+    s32 evAdd;
+    s32 prevC15;
+    struct SoundInfo *soundInfo = SOUND_INFO_PTR;
+    vu8 *nrx0ptr;
+    vu8 *nrx1ptr;
+    vu8 *nrx2ptr;
+    vu8 *nrx3ptr;
+    vu8 *nrx4ptr;
+
+    // Most comparision operations that cast to s8 perform 'and' by 0xFF.
+    int xFF = 0xff;
+
+    if (soundInfo->c15)
+        soundInfo->c15--;
+    else
+        soundInfo->c15 = 14;
+
+    for (ch = 1, channels = soundInfo->cgbChans; ch <= 4; ch++, channels++)
+    {
+        if (!(channels->sf & 0xc7))
+            continue;
+
+        switch (ch)
+        {
+        case 1:
+            nrx0ptr = (vu8 *)(REG_ADDR_NR10);
+            nrx1ptr = (vu8 *)(REG_ADDR_NR11);
+            nrx2ptr = (vu8 *)(REG_ADDR_NR12);
+            nrx3ptr = (vu8 *)(REG_ADDR_NR13);
+            nrx4ptr = (vu8 *)(REG_ADDR_NR14);
+            break;
+        case 2:
+            nrx0ptr = (vu8 *)(REG_ADDR_NR10+1);
+            nrx1ptr = (vu8 *)(REG_ADDR_NR21);
+            nrx2ptr = (vu8 *)(REG_ADDR_NR22);
+            nrx3ptr = (vu8 *)(REG_ADDR_NR23);
+            nrx4ptr = (vu8 *)(REG_ADDR_NR24);
+            break;
+        case 3:
+            nrx0ptr = (vu8 *)(REG_ADDR_NR30);
+            nrx1ptr = (vu8 *)(REG_ADDR_NR31);
+            nrx2ptr = (vu8 *)(REG_ADDR_NR32);
+            nrx3ptr = (vu8 *)(REG_ADDR_NR33);
+            nrx4ptr = (vu8 *)(REG_ADDR_NR34);
+            break;
+        default:
+            nrx0ptr = (vu8 *)(REG_ADDR_NR30+1);
+            nrx1ptr = (vu8 *)(REG_ADDR_NR41);
+            nrx2ptr = (vu8 *)(REG_ADDR_NR42);
+            nrx3ptr = (vu8 *)(REG_ADDR_NR43);
+            nrx4ptr = (vu8 *)(REG_ADDR_NR44);
+            break;
+        }
+
+        prevC15 = soundInfo->c15;
+        evAdd = *nrx2ptr;
+
+        if (channels->sf & 0x80)
+        {
+            if (!(channels->sf & 0x40))
+            {
+                channels->sf = 3;
+                channels->mo = 3;
+                CgbModVol(channels);
+                switch (ch)
+                {
+                case 1:
+                    *nrx0ptr = channels->sw;
+                    // fallthrough
+                case 2:
+                    *nrx1ptr = ((u32)channels->wp << 6) + channels->le;
+                    goto loc_82E0E30;
+                    break;
+                case 3:
+                    if ((u32)channels->wp != channels->cp)
+                    {
+                        *nrx0ptr = 0x40;
+                        REG_WAVE_RAM0 = channels->wp[0];
+                        REG_WAVE_RAM1 = channels->wp[1];
+                        REG_WAVE_RAM2 = channels->wp[2];
+                        REG_WAVE_RAM3 = channels->wp[3];
+                        channels->cp = (u32)channels->wp;
+                    }
+                    *nrx0ptr = 0;
+                    *nrx1ptr = channels->le;
+                    if (channels->le)
+                        channels->n4 = -64;
+                    else
+                        channels->n4 = -128;
+                    break;
+                default:
+                    *nrx1ptr = channels->le;
+                    *nrx3ptr = (u32)channels->wp << 3;
+                loc_82E0E30:
+                    evAdd = channels->at + 8;
+                    if (channels->le)
+                        channels->n4 = 64;
+                    else
+                        channels->n4 = 0;
+                    break;
+                }
+                channels->ec = channels->at;
+                if ((s8)(channels->at & xFF))
+                {
+                    channels->ev = 0;
+                    goto EC_MINUS;
+                }
+                else
+                {
+                    goto loc_82E0F96;
+                }
+            }
+            else
+            {
+                goto loc_82E0E82;
+            }
+        }
+        else if (channels->sf & 0x04)
+        {
+            channels->echoLength--;
+            if ((s8)(channels->echoLength & xFF) <= 0)
+            {
+            loc_82E0E82:
+                CgbOscOff(ch);
+                channels->sf = 0;
+                goto LAST_LABEL;
+            }
+            goto loc_82E0FD6;
+        }
+        else if ((channels->sf & 0x40) && (channels->sf & 0x03))
+        {
+            channels->sf &= 0xfc;
+            channels->ec = channels->re;
+            if ((s8)(channels->re & xFF))
+            {
+                channels->mo |= 1;
+                if (ch != 3)
+                {
+                    evAdd = channels->re;
+                }
+                goto EC_MINUS;
+            }
+            else
+            {
+                goto loc_82E0F02;
+            }
+        }
+        else
+        {
+        loc_82E0ED0:
+            if (channels->ec == 0)
+            {
+                if (ch == 3)
+                {
+                    channels->mo |= 1;
+                }
+                CgbModVol(channels);
+                if ((channels->sf & 0x3) == 0)
+                {
+                    channels->ev--;
+                    if ((s8)(channels->ev & xFF) <= 0)
+                    {
+                    loc_82E0F02:
+                        channels->ev = ((channels->eg * channels->echoVolume) + 0xFF) >> 8;
+                        if (channels->ev)
+                        {
+                            channels->sf |= 0x4;
+                            channels->mo |= 1;
+                            if (ch != 3)
+                            {
+                                evAdd = 8;
+                            }
+                            goto loc_82E0FD6;
+                        }
+                        else
+                        {
+                            goto loc_82E0E82;
+                        }
+                    }
+                    else
+                    {
+                        channels->ec = channels->re;
+                    }
+                }
+                else if ((channels->sf & 0x3) == 1)
+                {
+                loc_82E0F3A:
+                    channels->ev = channels->sg;
+                    channels->ec = 7;
+                }
+                else if ((channels->sf & 0x3) == 2)
+                {
+                    int ev, sg;
+
+                    channels->ev--;
+                    ev = (s8)(channels->ev & xFF);
+                    sg = (s8)(channels->sg);
+                    if (ev <= sg)
+                    {
+                    loc_82E0F5A:
+                        if (channels->su == 0)
+                        {
+                            channels->sf &= 0xfc;
+                            goto loc_82E0F02;
+                        }
+                        else
+                        {
+                            channels->sf--;
+                            channels->mo |= 1;
+                            if (ch != 3)
+                            {
+                                evAdd = 8;
+                            }
+                            goto loc_82E0F3A;
+                        }
+                    }
+                    else
+                    {
+                        channels->ec = channels->de;
+                    }
+                }
+                else
+                {
+                    channels->ev++;
+                    if ((u8)(channels->ev & xFF) >= channels->eg)
+                    {
+                    loc_82E0F96:
+                        channels->sf--;
+                        channels->ec = channels->de;
+                        if ((u8)(channels->ec & xFF))
+                        {
+                            channels->mo |= 1;
+                            channels->ev = channels->eg;
+                            if (ch != 3)
+                            {
+                                evAdd = channels->de;
+                            }
+                        }
+                        else
+                        {
+                            goto loc_82E0F5A;
+                        }
+                    }
+                    else
+                    {
+                        channels->ec = channels->at;
+                    }
+                }
+            }
+        }
+
+    EC_MINUS:
+        channels->ec--;
+        if (prevC15 == 0)
+        {
+            prevC15--;
+            goto loc_82E0ED0;
+        }
+
+    loc_82E0FD6:
+        if (channels->mo & 0x2)
+        {
+            if (ch < 4 && (channels->ty & 0x08))
+            {
+                int biasH = REG_SOUNDBIAS_H;
+
+                if (biasH < 64)
+                {
+                    channels->fr = (channels->fr + 2) & 0x7fc;
+                }
+                else if (biasH < 128)
+                {
+                    channels->fr = (channels->fr + 1) & 0x7fe;
+                }
+            }
+            if (ch != 4)
+            {
+                *nrx3ptr = channels->fr;
+            }
+            else
+            {
+                *nrx3ptr = (*nrx3ptr & 0x08) | channels->fr;
+            }
+            channels->n4 = (channels->n4 & 0xC0) + (*((u8*)(&channels->fr) + 1));
+            *nrx4ptr = (s8)(channels->n4 & xFF);
+        }
+
+        if (channels->mo & 1)
+        {
+            REG_NR51 = (REG_NR51 & ~channels->panMask) | channels->pan;
+            if (ch == 3)
+            {
+                *nrx2ptr = gCgb3Vol[channels->ev];
+                if (channels->n4 & 0x80)
+                {
+                    *nrx0ptr = 0x80;
+                    *nrx4ptr = channels->n4;
+                    channels->n4 &= 0x7f;
+                }
+            }
+            else
+            {
+                evAdd &= 0xf;
+                *nrx2ptr = (channels->ev << 4) + evAdd;
+                *nrx4ptr = channels->n4 | 0x80;
+                if (ch == 1 && !(*nrx0ptr & 0x08))
+                {
+                    *nrx4ptr = channels->n4 | 0x80;
+                }
+            }
+        }
+
+    LAST_LABEL:
+        channels->mo = 0;
+    }
+}