Add DMA control macros and small memory copy test

4 files changed, 101 insertions, 74 deletions

diff --git a/src/common.h b/src/common.h
index 669fb6e..e3405be 100644
--- a/src/common.h
+++ b/src/common.h
@@ -305,6 +305,7 @@ unpack_1bb(u8 hex) {
 }
 
 // Unpack N tiles packed at 1bpp.
+static inline void
 unpack_tiles(u32 *src, u32 *dst, size_t n_tiles) {
     u32 *target_src = src + n_tiles * 2;
     while (src != target_src) {
@@ -316,4 +317,72 @@ unpack_tiles(u32 *src, u32 *dst, size_t n_tiles) {
     }
 }
 
+//
+// Direct Memory Access (DMA)
+//
+
+
+// Source, destination, and control registers.
+#define DMA_SRC(N)  *((vu32*) 0x040000B0 + (N) * 12)
+#define DMA_DST(N)  *((vu32*) 0x040000B4 + (N) * 12)
+#define DMA_CTRL(N) *((vu32*) 0x040000B8 + (N) * 12)
+
+// DMA control bits.
+#define DMA_DST_INC    (0 << 0x15)
+#define DMA_DST_DEC    (1 << 0x15)
+#define DMA_DST_FIXED  (2 << 0x15)
+#define DMA_DST_RELOAD (3 << 0x15)
+#define DMA_SRC_INC    (0 << 0x17)
+#define DMA_SRC_DEC    (1 << 0x17)
+#define DMA_SRC_FIXED  (2 << 0x17)
+#define DMA_REPEAT     (1 << 0x19)
+#define DMA_CHUNK_16   (0 << 0x1A)
+#define DMA_CHUNK_32   (1 << 0x1A)
+#define DMA_NOW        (0 << 0x1C)
+#define DMA_VBLANK     (1 << 0x1C)
+#define DMA_HBLANK     (2 << 0x1C)
+#define DMA_REFRESH    (3 << 0x1C)
+#define DMA_IRQ        (1 << 0x1E)
+#define DMA_ENABLE     (1 << 0x1F)
+
+// Custom struct for cleaner DMA transfer functions.
+typedef struct DmaStr {
+    const void *src;
+    void *dst;
+    u32 ctrl;
+} DmaStr;
+
+#define DMA_TRANSFER ((volatile DmaStr*) 0x040000B0)
+
+// Transfer `count` number of chunks from src to dst using a DMA channel. Note
+// that chunks are not bytes, but instead configured based on bits set by
+// DMA_CTRL.
+inline void
+dma_transfer_copy(void *dst, const void *src, u32 count, int channel, u32 options) {
+    DMA_TRANSFER[channel].ctrl = 0;
+    DMA_TRANSFER[channel].src = src;
+    DMA_TRANSFER[channel].dst = dst;
+    DMA_TRANSFER[channel].ctrl = count | options;
+}
+
+inline void
+dma_transfer_fill(void *dst, volatile u32 src, u32 count, int channel, u32 options) {
+    DMA_TRANSFER[channel].ctrl = 0;
+    DMA_TRANSFER[channel].src = (const void *)&src;
+    DMA_TRANSFER[channel].dst = dst;
+    DMA_TRANSFER[channel].ctrl = count | options | DMA_SRC_FIXED;
+}
+
+// Copy N number of bytes using a DMA channel.
+inline void
+dma_copy(void *dst, const void *src, u32 size, int channel) {
+    dma_transfer_copy(dst, src, size / 4, channel, DMA_CHUNK_32 | DMA_ENABLE);
+}
+
+// Fill the dst location with the word set at src.
+inline void
+dma_fill(void *dst, const void *src, u32 size, int channel) {
+    dma_transfer_fill(dst, src, size / 4, channel, DMA_CHUNK_32 | DMA_ENABLE);
+}
+
 #endif // GBAEXP_COMMON_H
diff --git a/src/main.c b/src/main.c
index 3bd5865..efd460f 100644
--- a/src/main.c
+++ b/src/main.c
@@ -22,83 +22,43 @@ int main(void) {
     init_sprite_pal(0, COLOR_WHITE);
     init_sprites(0);
     init_button_sprites();
+    Color colors[16] = {
+        COLOR_BLUE,
+        COLOR_BLUE,
+        COLOR_BLUE,
+        COLOR_BLUE,
+        COLOR_BLUE,
+        COLOR_BLUE,
+        COLOR_BLUE,
+        COLOR_BLUE,
+        COLOR_BLUE,
+        COLOR_BLUE,
+        COLOR_BLUE,
+        COLOR_BLUE,
+        COLOR_BLUE,
+        COLOR_BLUE,
+        COLOR_BLUE,
+        COLOR_BLUE,
+    };
+    // These should be equivalent here, but remember that the dma_copy and
+    // dma_fill functions will always work on U32 chunks.
+    //
+    // memcpy(&PAL_BUFFER_SPRITES[0], colors, 16 * sizeof(Color));
+    // dma_copy(&PAL_BUFFER_SPRITES[0], colors, 16 * sizeof(Color), 3);
+
+    u32 color = COLOR_RED | COLOR_RED << 16;
+    dma_fill(&PAL_BUFFER_SPRITES[0], color, 16 * sizeof(Color), 3);
 
     // Initialize text engine.
-    txt_init(0, COLOR_RED, 0);
-    txt_position(0, 6);
-    txt_printf("Strings: %s\n", "Hello World");
-    txt_printf("Signed ints: %d\n", -100000);
-    txt_printf("Unsigned ints: %u\n", 1234567);
-    txt_printf("Hex values: 0x%x\n", 1024);
+    // txt_init(0, COLOR_RED, 0);
+    // txt_printf("TEST");
 
     int frame_counter = 0;
-    int x = 0;
-    int y = 0;
     while(true) {
         wait_vsync();
         poll_keys();
 
-        txt_position(0, 0);
-        txt_printf("Frame counter: %d\n", frame_counter);
-
-        if (key_hold(KEY_DOWN)) {
-            y += 3;
-        }
-        if (key_hold(KEY_UP)) {
-            y -= 3;
-        }
-        if (key_hold(KEY_LEFT)) {
-            x -= 3;
-        }
-        if (key_hold(KEY_RIGHT)) {
-            x += 3;
-        }
-
-        if (key_pressed(KEY_A)) {
-            txt_clear_line();
-            txt_printf("Pressed key: A");
-        }
-        if (key_pressed(KEY_B)) {
-            txt_clear_line();
-            txt_printf("Pressed key: B");
-        }
-        if (key_pressed(KEY_L)) {
-            txt_clear_line();
-            txt_printf("Pressed key: L");
-        }
-        if (key_pressed(KEY_R)) {
-            txt_clear_line();
-            txt_printf("Pressed key: R");
-        }
-        if (key_pressed(KEY_START)) {
-            txt_clear_line();
-            txt_printf("Pressed key: Start");
-        }
-        if (key_pressed(KEY_SELECT)) {
-            txt_clear_line();
-            txt_printf("Pressed key: Select");
-        }
-        if (key_pressed(KEY_UP)) {
-            txt_clear_line();
-            txt_printf("Pressed key: Up");
-        }
-        if (key_pressed(KEY_DOWN)) {
-            txt_clear_line();
-            txt_printf("Pressed key: Down");
-        }
-        if (key_pressed(KEY_LEFT)) {
-            txt_clear_line();
-            txt_printf("Pressed key: Left");
-        }
-        if (key_pressed(KEY_RIGHT)) {
-            txt_clear_line();
-            txt_printf("Pressed key: Right");
-        }
-
         frame_counter++;
-        // BG_H_SCROLL_0 = x;
-        // BG_V_SCROLL_0 = y;
-
         update_button_sprites();
     };
 
diff --git a/src/sprites.h b/src/sprites.h
index 88ca787..0b55f0d 100644
--- a/src/sprites.h
+++ b/src/sprites.h
@@ -73,7 +73,6 @@ init_sprite_pal(size_t starting_index, Color col) {
     for (size_t i = 0; i < 16; ++i) {
         PAL_BUFFER_SPRITES[i + starting_index] = col;
     }
-
 }
 
 #endif // GBAEXP_SPRITES_H
diff --git a/src/text.h b/src/text.h
index e38c220..c852fc2 100644
--- a/src/text.h
+++ b/src/text.h
@@ -2,6 +2,7 @@
 #define GBAEXP_TILES_H
 
 #include <stdarg.h>
+#include <stdio.h>
 
 #include "common.h"
 #include "bd-font.c"
@@ -75,11 +76,9 @@ txt_printf(char *msg, ...) {
     va_list arg_list;
     va_start(arg_list, msg);
     char c;
-    char prev_c;
     while ((c = *msg++) != '\0') {
         if (c != '%') {
             txt_putc(c);
-            prev_c = c;
             continue;
         }
         c = *msg++;
@@ -88,19 +87,19 @@ txt_printf(char *msg, ...) {
                 txt_puts(va_arg(arg_list, char *));
             } break;
             case 'd': {
-                char buf[32] = {0};
+                char buf[12] = {0};
                 int x = va_arg(arg_list, int);
                 sprintf(buf, "%d", x);
                 txt_puts(buf);
             } break;
             case 'u': {
-                char buf[32] = {0};
+                char buf[12] = {0};
                 unsigned int x = va_arg(arg_list, unsigned int);
                 sprintf(buf, "%u", x);
                 txt_puts(buf);
             } break;
             case 'x': {
-                char buf[32] = {0};
+                char buf[12] = {0};
                 unsigned int x = va_arg(arg_list, unsigned int);
                 sprintf(buf, "%x", x);
                 txt_puts(buf);