1 files changed, 132 insertions, 1 deletions

diff --git a/src/common.h b/src/common.h
index e3405be..dac48ad 100644
--- a/src/common.h
+++ b/src/common.h
@@ -46,6 +46,15 @@
 #define DISP_OBJ        (1 << 12)
 #define DISP_ENABLE_SPRITES DISP_OBJ | DISP_OBJ_1D
 
+// These bits are used to control the DISP_STATUS register.
+#define DISP_VBLANK_STATUS     (1 << 0x0)
+#define DISP_HBLANK_STATUS     (1 << 0x1)
+#define DISP_VCOUNT_STATUS     (1 << 0x2)
+#define DISP_VBLANK_IRQ        (1 << 0x3)
+#define DISP_HBLANK_IRQ        (1 << 0x4)
+#define DISP_VCOUNT_IRQ        (1 << 0x5)
+#define DISP_VCOUNT_TRIGGER(N) ((N) << 0x8)
+
 // Registers to control of BG layers.
 #define BG_CTRL(N) *((vu16*)(0x04000008 + 0x0002 * (N)))
 
@@ -245,8 +254,14 @@ u32 profile_stop(void) {
 // Input handling.
 //
 
-// Memory address for key input register
+// Memory address for key input and control register
 #define KEY_INPUTS *((vu16*) 0x04000130)
+#define KEY_CTRL   *((vu16*) 0x04000132)
+
+// Key control register bits.
+#define KEY_IRQ_KEY(N) (N)
+#define KEY_IRQ        (1 << 0xE)
+#define KEY_IRQ_IF_SET (1 << 0xF)
 
 // Alias for key pressing bits.
 #define KEY_A      (1 << 0)
@@ -385,4 +400,120 @@ dma_fill(void *dst, const void *src, u32 size, int channel) {
     dma_transfer_fill(dst, src, size / 4, channel, DMA_CHUNK_32 | DMA_ENABLE);
 }
 
+//
+// Interrupts.
+//
+
+#define IRQ_ENABLE   *((vu16*) 0x04000200)
+#define IRQ_ACK      *((vu16*) 0x04000202)
+#define IRQ_CTRL     *((vu16*) 0x04000208)
+#define IRQ_ACK_BIOS *((vu16*) 0x03007FF8)
+
+typedef enum {
+    IRQ_VBLANK,
+    IRQ_HBLANK,
+    IRQ_VCOUNT,
+    IRQ_TIMER_0,
+    IRQ_TIMER_1,
+    IRQ_TIMER_2,
+    IRQ_TIMER_3,
+    IRQ_SERIAL,
+    IRQ_DMA_0,
+    IRQ_DMA_1,
+    IRQ_DMA_2,
+    IRQ_DMA_3,
+    IRQ_KEYPAD,
+    IRQ_GAMEPAK,
+} IrqIndex;
+
+typedef void (*IrsFunc)(void);
+
+IrsFunc irs_table[] = {
+    [IRQ_VBLANK ] = NULL,
+    [IRQ_HBLANK ] = NULL,
+    [IRQ_VCOUNT ] = NULL,
+    [IRQ_TIMER_0] = NULL,
+    [IRQ_TIMER_1] = NULL,
+    [IRQ_TIMER_2] = NULL,
+    [IRQ_TIMER_3] = NULL,
+    [IRQ_SERIAL ] = NULL,
+    [IRQ_DMA_0  ] = NULL,
+    [IRQ_DMA_1  ] = NULL,
+    [IRQ_DMA_2  ] = NULL,
+    [IRQ_DMA_3  ] = NULL,
+    [IRQ_KEYPAD ] = NULL,
+    [IRQ_GAMEPAK] = NULL,
+};
+
+void
+irq_enable(IrqIndex idx) {
+    switch (idx) {
+        case IRQ_VBLANK:  { DISP_STATUS |= DISP_VBLANK_IRQ; } break;
+        case IRQ_HBLANK:  { DISP_STATUS |= DISP_HBLANK_IRQ; } break;
+        case IRQ_VCOUNT:  { DISP_STATUS |= DISP_VCOUNT_IRQ; } break;
+        case IRQ_TIMER_0: { TIMER_CTRL_0 |= TIMER_CTRL_IRQ; } break;
+        case IRQ_TIMER_1: { TIMER_CTRL_1 |= TIMER_CTRL_IRQ; } break;
+        case IRQ_TIMER_2: { TIMER_CTRL_2 |= TIMER_CTRL_IRQ; } break;
+        case IRQ_TIMER_3: { TIMER_CTRL_3 |= TIMER_CTRL_IRQ; } break;
+        case IRQ_SERIAL:  { /* TODO: Set REG_SERIAL? */  } break;
+        case IRQ_DMA_0:   { DMA_CTRL(0) |= DMA_IRQ; } break;
+        case IRQ_DMA_1:   { DMA_CTRL(1) |= DMA_IRQ; } break;
+        case IRQ_DMA_2:   { DMA_CTRL(2) |= DMA_IRQ; } break;
+        case IRQ_DMA_3:   { DMA_CTRL(3) |= DMA_IRQ; } break;
+        case IRQ_KEYPAD:  { KEY_CTRL |= KEY_IRQ; } break;
+        case IRQ_GAMEPAK: { /* Nothing to do here...*/  } break;
+    }
+    IRQ_ENABLE |= (1 << idx);
+}
+
+void
+irq_disable(IrqIndex idx) {
+    switch (idx) {
+        case IRQ_VBLANK:  { DISP_STATUS &= ~DISP_VBLANK_IRQ; } break;
+        case IRQ_HBLANK:  { DISP_STATUS &= ~DISP_HBLANK_IRQ; } break;
+        case IRQ_VCOUNT:  { DISP_STATUS &= ~DISP_VCOUNT_IRQ; } break;
+        case IRQ_TIMER_0: { TIMER_CTRL_0 &= ~TIMER_CTRL_IRQ; } break;
+        case IRQ_TIMER_1: { TIMER_CTRL_1 &= ~TIMER_CTRL_IRQ; } break;
+        case IRQ_TIMER_2: { TIMER_CTRL_2 &= ~TIMER_CTRL_IRQ; } break;
+        case IRQ_TIMER_3: { TIMER_CTRL_3 &= ~TIMER_CTRL_IRQ; } break;
+        case IRQ_SERIAL:  { /* TODO: Set REG_SERIAL? */  } break;
+        case IRQ_DMA_0:   { DMA_CTRL(0) &= ~DMA_IRQ; } break;
+        case IRQ_DMA_1:   { DMA_CTRL(1) &= ~DMA_IRQ; } break;
+        case IRQ_DMA_2:   { DMA_CTRL(2) &= ~DMA_IRQ; } break;
+        case IRQ_DMA_3:   { DMA_CTRL(3) &= ~DMA_IRQ; } break;
+        case IRQ_KEYPAD:  { KEY_CTRL &= ~KEY_IRQ; } break;
+        case IRQ_GAMEPAK: { /* Nothing to do here...*/  } break;
+    }
+    IRQ_ENABLE &= ~(1 << idx);
+}
+
+void
+irs_set(IrqIndex idx, IrsFunc func) {
+    // Store IRQ_CTRL status and disable interrupts for now.
+    u16 irq_ctrl = IRQ_CTRL;
+    IRQ_CTRL = 0;
+
+    // Update the IRS table and enable/disable the given IRQ.
+    irs_table[idx] = func;
+    if (func == NULL) {
+        irq_disable(idx);
+    } else {
+        irq_enable(idx);
+    }
+
+    // Restore previous irq_ctrl.
+    IRQ_CTRL = irq_ctrl;
+}
+
+#define IRS_MAIN *(IrsFunc*)(0x03007FFC)
+
+// External irs_main function, has to be written in ARM assembly.
+void irs_main(void);
+
+void
+irq_init() {
+    IRS_MAIN = irs_main;
+    IRQ_CTRL = 1;
+}
+
 #endif // GBAEXP_COMMON_H