Document N64DD data buffer (#2665)

src/n64dd/n64dd_data_buffer.c

@@ -1,4 +1,8 @@
 #include "n64dd.h"
 
-// Buffer used for reading from the disk?
-u8 B_801DC000[0x4D10];
+/**
+ * Buffer used during the process of reading from the disk
+ * Used to directly read individual blocks from the disk before copying to the final destination.
+ * As blocks are read directly into this buffer from the disk, it should be 16-byte aligned.
+ */
+ALIGNED(16) u8 gN64DDDiskReadTemporaryBuffer[MAX_BLK_SIZE];

src/n64dd/z_n64dd.c

@@ -36,7 +36,7 @@ typedef struct struct_801D9B90 {
 
 s32 func_801C7A1C(struct_801E0D18* arg0);
 
-void* D_801D2E50 = &B_801DC000;
+void* D_801D2E50 = &gN64DDDiskReadTemporaryBuffer;
 s32 (*D_801D2E54)(struct_801E0D18*) = func_801C7A1C;
 
 struct_801D9B90 B_801D9B90;