label more of scanline_effect.c

1 files changed, 96 insertions, 74 deletions

diff --git a/src/scanline_effect.c b/src/scanline_effect.c
index e9cf0d02a..0fa5b024d 100644
--- a/src/scanline_effect.c
+++ b/src/scanline_effect.c
@@ -4,27 +4,26 @@
 #include "trig.h"
 #include "scanline_effect.h"
 
-// Control value to ransfer a single 16-bit value at HBlank
-#define HBLANK_DMA_CONTROL_16BIT (((DMA_ENABLE | DMA_START_HBLANK | DMA_REPEAT | DMA_DEST_RELOAD) << 16) | 1)
+static void CopyValue16Bit(void);
+static void CopyValue32Bit(void);
 
-static void sub_80896F4(void);
-static void sub_8089714(void);
-
-extern u16 gUnknown_030041B0;
-extern u16 gBattle_BG1_Y;
-extern u16 gUnknown_030041B8;
-extern u16 gBattle_BG2_Y;
-extern u16 gBattle_BG2_X;
 extern u16 gBattle_BG0_Y;
 extern u16 gBattle_BG0_X;
 extern u16 gBattle_BG1_X;
+extern u16 gBattle_BG1_Y;
+extern u16 gBattle_BG2_X;
+extern u16 gBattle_BG2_Y;
+extern u16 gUnknown_030041B0;
+extern u16 gUnknown_030041B8;
 
-extern u8 gUnknown_0202FFA4;
+EWRAM_DATA static u8 gUnknown_0202FFA4 = 0;
 
-extern struct ScanlineEffect gScanlineEffect;
+struct ScanlineEffect gScanlineEffect;
 
-// Is this a struct?
-extern u16 gUnknown_03004DE0[][0x3C0];
+// Per-scanline register values.
+// This is double buffered so that it can be safely written to at any time
+// without overwriting the buffer that the DMA is currently reading
+u16 gScanlineEffectRegBuffers[2][0x3C0];
 
 void ScanlineEffect_Stop(void)
 {
@@ -39,11 +38,11 @@ void ScanlineEffect_Stop(void)
 
 void dp12_8087EA4(void)
 {
-    CpuFill16(0, gUnknown_03004DE0, 0x780 * 2);
-    gScanlineEffect.src[0] = 0;
-    gScanlineEffect.src[1] = 0;
-    gScanlineEffect.dest = 0;
-    gScanlineEffect.unkC = 0;
+    CpuFill16(0, gScanlineEffectRegBuffers, sizeof(gScanlineEffectRegBuffers));
+    gScanlineEffect.src[0] = NULL;
+    gScanlineEffect.src[1] = NULL;
+    gScanlineEffect.dmaDest = NULL;
+    gScanlineEffect.dmaControl = 0;
     gScanlineEffect.srcBank = 0;
     gScanlineEffect.unk15 = 0;
     gScanlineEffect.unk16 = 0;
@@ -51,31 +50,35 @@ void dp12_8087EA4(void)
     gScanlineEffect.taskId = 0xFF;
 }
 
-void sub_80895F8(struct UnknownTaskStruct unk)
+void ScanlineEffect_SetParams(struct ScanlineEffectParams params)
 {
-    if (unk.control == HBLANK_DMA_CONTROL_16BIT)  // 16 bit
+    if (params.dmaControl == SCANLINE_EFFECT_DMACNT_16BIT)  // 16-bit
     {
-        gScanlineEffect.src[0] = &gUnknown_03004DE0[0][1];
-        gScanlineEffect.src[1] = &gUnknown_03004DE0[1][1];
-        gScanlineEffect.unk10 = sub_80896F4;
+        // Set the DMA src to the value for the second scanline because the
+        // first DMA transfer occurs in HBlank *after* the first scanline is drawn
+        gScanlineEffect.src[0] = (u16 *)gScanlineEffectRegBuffers[0] + 1;
+        gScanlineEffect.src[1] = (u16 *)gScanlineEffectRegBuffers[1] + 1;
+        gScanlineEffect.setFirstScanlineReg = CopyValue16Bit;
     }
     else  // assume 32-bit
     {
-        gScanlineEffect.src[0] = &gUnknown_03004DE0[0][2];
-        gScanlineEffect.src[1] = &gUnknown_03004DE0[1][2];
-        gScanlineEffect.unk10 = sub_8089714;
+        // Set the DMA src to the value for the second scanline because the
+        // first DMA transfer occurs in HBlank *after* the first scanline is drawn
+        gScanlineEffect.src[0] = (u32 *)gScanlineEffectRegBuffers[0] + 1;
+        gScanlineEffect.src[1] = (u32 *)gScanlineEffectRegBuffers[1] + 1;
+        gScanlineEffect.setFirstScanlineReg = CopyValue32Bit;
     }
 
-    gScanlineEffect.unkC = unk.control;
-    gScanlineEffect.dest = unk.dest;
-    gScanlineEffect.unk15 = unk.unk8;
-    gScanlineEffect.unk16 = unk.unk9;
-    gScanlineEffect.unk17 = unk.unk9;
+    gScanlineEffect.dmaControl = params.dmaControl;
+    gScanlineEffect.dmaDest = params.dmaDest;
+    gScanlineEffect.unk15 = params.unk8;
+    gScanlineEffect.unk16 = params.unk9;
+    gScanlineEffect.unk17 = params.unk9;
 }
 
-void ScanlineEffect_TransferDma(void)
+void ScanlineEffect_InitHBlankDmaTransfer(void)
 {
-    if (gScanlineEffect.unk15)
+    if (gScanlineEffect.unk15 != 0)
     {
         if (gScanlineEffect.unk15 == 3)
         {
@@ -86,28 +89,44 @@ void ScanlineEffect_TransferDma(void)
         else
         {
             DmaStop(0);
-            DmaSet(0, gScanlineEffect.src[gScanlineEffect.srcBank], gScanlineEffect.dest, gScanlineEffect.unkC);
-            gScanlineEffect.unk10();
+            // Set DMA to copy to dest register on each HBlank for the next frame.
+            // The HBlank DMA transfers do not occurr during VBlank, so the transfer
+            // will begin on the HBlank after the first scanline
+            DmaSet(0, gScanlineEffect.src[gScanlineEffect.srcBank], gScanlineEffect.dmaDest, gScanlineEffect.dmaControl);
+            // Manually set the reg for the first scanline
+            gScanlineEffect.setFirstScanlineReg();
+            // Swap current buffer
             gScanlineEffect.srcBank ^= 1;
         }
     }
 }
 
-static void sub_80896F4(void)
+// These two functions are used to copy the register for the first scanline,
+// depending whether it is a 16-bit register or a 32-bit register.
+
+static void CopyValue16Bit(void)
 {
-    u16 *dest = (u16 *)gScanlineEffect.dest;
-    u16 *src = (u16 *)&gUnknown_03004DE0[gScanlineEffect.srcBank];
+    u16 *dest = (u16 *)gScanlineEffect.dmaDest;
+    u16 *src = (u16 *)&gScanlineEffectRegBuffers[gScanlineEffect.srcBank];
+
     *dest = *src;
 }
 
-static void sub_8089714(void)
+static void CopyValue32Bit(void)
 {
-    u32 *dest = (u32 *)gScanlineEffect.dest;
-    u32 *src = (u32 *)&gUnknown_03004DE0[gScanlineEffect.srcBank];
+    u32 *dest = (u32 *)gScanlineEffect.dmaDest;
+    u32 *src = (u32 *)&gScanlineEffectRegBuffers[gScanlineEffect.srcBank];
+
     *dest = *src;
 }
 
-static void task00_for_dp12(u8 taskId)
+#define tStartLine      data[0]
+#define tEndLine        data[1]
+#define framesUntilMove data[4]
+#define tDelayInterval  data[5]
+#define tRegOffset      data[6]
+
+static void TaskFunc_UpdateWavePerFrame(u8 taskId)
 {
     int value = 0;
 
@@ -120,7 +139,7 @@ static void task00_for_dp12(u8 taskId)
     {
         if (gTasks[taskId].data[7])
         {
-            switch (gTasks[taskId].data[6])
+            switch (gTasks[taskId].tRegOffset)
             {
             case 0x0:
                 value = gBattle_BG0_X;
@@ -148,15 +167,16 @@ static void task00_for_dp12(u8 taskId)
                 break;
             }
         }
-        if (gTasks[taskId].data[4])
+        if (gTasks[taskId].framesUntilMove != 0)
         {
             int i;
             int offset;
-            gTasks[taskId].data[4]--;
+
+            gTasks[taskId].framesUntilMove--;
             offset = gTasks[taskId].data[3] + 320;
-            for (i = gTasks[taskId].data[0]; i < gTasks[taskId].data[1]; i++)
+            for (i = gTasks[taskId].tStartLine; i < gTasks[taskId].tEndLine; i++)
             {
-                gUnknown_03004DE0[gScanlineEffect.srcBank][i] = gUnknown_03004DE0[0][offset] + value;
+                gScanlineEffectRegBuffers[gScanlineEffect.srcBank][i] = gScanlineEffectRegBuffers[0][offset] + value;
                 offset++;
             }
         }
@@ -164,18 +184,17 @@ static void task00_for_dp12(u8 taskId)
         {
             int i;
             int offset;
-            gTasks[taskId].data[4] = gTasks[taskId].data[5];
+
+            gTasks[taskId].framesUntilMove = gTasks[taskId].tDelayInterval;
             offset = gTasks[taskId].data[3] + 320;
-            for (i = gTasks[taskId].data[0]; i < gTasks[taskId].data[1]; i++)
+            for (i = gTasks[taskId].tStartLine; i < gTasks[taskId].tEndLine; i++)
             {
-                gUnknown_03004DE0[gScanlineEffect.srcBank][i] = gUnknown_03004DE0[0][offset] + value;
+                gScanlineEffectRegBuffers[gScanlineEffect.srcBank][i] = gScanlineEffectRegBuffers[0][offset] + value;
                 offset++;
             }
             gTasks[taskId].data[3]++;
             if (gTasks[taskId].data[3] == gTasks[taskId].data[2])
-            {
                 gTasks[taskId].data[3] = 0;
-            }
         }
     }
 }
@@ -193,44 +212,47 @@ static void GenerateWave(u16 *buffer, u8 frequency, u8 amplitude, u8 unused)
     }
 }
 
-u8 ScanlineEffect_InitWave(u8 a1, u8 a2, u8 frequency, u8 amplitude, u8 a5, u8 a6, u8 a7)
+// Initializes a background "wave" effect that affects scanlines startLine (inclusive) to endLine (exclusive).
+// 'frequency' and 'amplitude' control the frequency and amplitude of the wave.
+// 'delayInterval' controls how fast the wave travels up the screen. The wave will shift upwards one scanline every 'delayInterval'+1 frames.
+// 'regOffset' is the offset of the video register to modify.
+u8 ScanlineEffect_InitWave(u8 startLine, u8 endLine, u8 frequency, u8 amplitude, u8 delayInterval, u8 regOffset, bool8 a7)
 {
     int i;
     int offset;
-    struct UnknownTaskStruct unk;
+    struct ScanlineEffectParams params;
     u8 taskId;
 
     dp12_8087EA4();
 
-    unk.dest = (void *)(REG_ADDR_BG0HOFS + a6);
-    unk.control = HBLANK_DMA_CONTROL_16BIT;
-    unk.unk8 = 1;
-    unk.unk9 = 0;
-
-    sub_80895F8(unk);
+    params.dmaDest = (void *)(REG_ADDR_BG0HOFS + regOffset);
+    params.dmaControl = SCANLINE_EFFECT_DMACNT_16BIT;
+    params.unk8 = 1;
+    params.unk9 = 0;
+    ScanlineEffect_SetParams(params);
 
-    taskId = CreateTask(task00_for_dp12, 0);
+    taskId = CreateTask(TaskFunc_UpdateWavePerFrame, 0);
 
-    gTasks[taskId].data[0] = a1;
-    gTasks[taskId].data[1] = a2;
-    gTasks[taskId].data[2] = 256 / frequency;
-    gTasks[taskId].data[3] = 0;
-    gTasks[taskId].data[4] = a5;
-    gTasks[taskId].data[5] = a5;
-    gTasks[taskId].data[6] = a6;
-    gTasks[taskId].data[7] = a7;
+    gTasks[taskId].tStartLine      = startLine;
+    gTasks[taskId].tEndLine        = endLine;
+    gTasks[taskId].data[2]         = 256 / frequency;
+    gTasks[taskId].data[3]         = 0;
+    gTasks[taskId].framesUntilMove = delayInterval;
+    gTasks[taskId].tDelayInterval  = delayInterval;
+    gTasks[taskId].tRegOffset      = regOffset;
+    gTasks[taskId].data[7]         = a7;
 
     gScanlineEffect.taskId = taskId;
     gUnknown_0202FFA4 = 0;
 
-    GenerateWave(&gUnknown_03004DE0[0][320], frequency, amplitude, a2 - a1);
+    GenerateWave(&gScanlineEffectRegBuffers[0][320], frequency, amplitude, endLine - startLine);
 
     offset = 320;
 
-    for (i = a1; i < a2; i++)
+    for (i = startLine; i < endLine; i++)
     {
-        gUnknown_03004DE0[0][i] = gUnknown_03004DE0[0][offset];
-        gUnknown_03004DE0[1][i] = gUnknown_03004DE0[0][offset];
+        gScanlineEffectRegBuffers[0][i] = gScanlineEffectRegBuffers[0][offset];
+        gScanlineEffectRegBuffers[1][i] = gScanlineEffectRegBuffers[0][offset];
         offset++;
     }