[nostalgia/core/gba] Add wfi functions

src/nostalgia/core/gba/CMakeLists.txt

@@ -3,6 +3,7 @@ if(NOSTALGIA_BUILD_TYPE STREQUAL "GBA")
 
 	add_library(
 		NostalgiaCore-GBA
+			bios.s
 			core.cpp
 			gfx.cpp
 			irq.arm.cpp

src/nostalgia/core/gba/bios.hpp

@@ -0,0 +1,21 @@
+/*
+ * Copyright 2016 - 2020 gary@drinkingtea.net
+ *
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/.
+ */
+
+#pragma once
+
+extern "C" {
+
+void nostalgia_core_halt();
+
+void nostalgia_core_stop();
+
+void nostalgia_core_wfi();
+
+void nostalgia_core_vblankwfi();
+
+}

src/nostalgia/core/gba/bios.s

@@ -0,0 +1,37 @@
+//
+// Copyright 2016 - 2020 gtalent2@gmail.com
+//
+// This Source Code Form is subject to the terms of the Mozilla Public
+// License, v. 2.0. If a copy of the MPL was not distributed with this
+// file, You can obtain one at http://mozilla.org/MPL/2.0/.
+//
+
+.section .iwram, "ax", %progbits
+.thumb
+.align
+
+.global nostalgia_core_halt
+.type nostalgia_core_halt, %function
+nostalgia_core_halt:
+	swi 2
+	bx lr
+
+.global nostalgia_core_stop
+.type nostalgia_core_stop, %function
+nostalgia_core_stop:
+	swi 3
+	bx lr
+
+.global nostalgia_core_wfi
+.type nostalgia_core_wfi, %function
+nostalgia_core_wfi:
+	swi 4
+	bx lr
+
+.global nostalgia_core_vblankwfi
+.type nostalgia_core_vblankwfi, %function
+nostalgia_core_vblankwfi:
+	swi 5
+	bx lr
+
+// vim: ft=armv4

src/nostalgia/core/gba/core.cpp

@@ -10,6 +10,7 @@
 #include <nostalgia/core/core.hpp>
 
 #include "addresses.hpp"
+#include "bios.hpp"
 #include "irq.hpp"
 
 extern "C" void isr();
@@ -19,7 +20,7 @@ namespace nostalgia::core {
 // Timer Consts
 constexpr auto NanoSecond = 1000000000;
 constexpr auto MilliSecond = 1000;
-constexpr int TicksMs59ns = (NanoSecond / MilliSecond) / 59.59;
+constexpr int TicksMs59ns = 65535 - (NanoSecond / MilliSecond) / 59.59;
 
 extern volatile ox::Uint<config::GbaTimerBits> g_timerMs;
 
@@ -45,6 +46,7 @@ ox::Error init(Context *ctx) {
 
 ox::Error run(Context*) {
 	while (1) {
+		nostalgia_core_vblankwfi();
 	}
 	return OxError(0);
 }

src/nostalgia/core/gba/gfx.cpp

@@ -14,12 +14,14 @@
 #include <nostalgia/core/gfx.hpp>
 
 #include "addresses.hpp"
+#include "bios.hpp"
 #include "irq.hpp"
 #include "gfx.hpp"
 
 namespace nostalgia::core {
 
 constexpr auto GbaTileColumns = 32;
+constexpr auto GbaTileRows = 32;
 
 constexpr uint16_t DispStat_irq_vblank = 1 << 3;
 constexpr uint16_t DispStat_irq_hblank = 1 << 4;
@@ -209,6 +211,11 @@ void setTile(Context*, int layer, int column, int row, uint8_t tile) {
 	MEM_BG_MAP[layer][row * GbaTileColumns + column] = tile;
 }
 
+// Do NOT use Context in the GBA version of this function.
+void clearTileLayer(Context*, int layer) {
+	memset(&MEM_BG_MAP[layer], 0, GbaTileRows * GbaTileColumns);
+}
+
 void setSprite(unsigned idx, unsigned x, unsigned y, unsigned tileIdx) {
 	GbaSpriteAttrUpdate oa;
 	oa.attr0 = static_cast<uint16_t>(y & ox::onMask<uint8_t>(7))
@@ -217,7 +224,9 @@ void setSprite(unsigned idx, unsigned x, unsigned y, unsigned tileIdx) {
 	oa.attr2 = static_cast<uint16_t>(tileIdx & ox::onMask<uint16_t>(8));
 	oa.idx = idx;
 	// block until g_spriteUpdates is less than buffer len
-	while (g_spriteUpdates >= config::GbaSpriteBufferLen);
+	if (g_spriteUpdates >= config::GbaSpriteBufferLen) {
+		nostalgia_core_vblankwfi();
+	}
 	REG_IE &= ~Int_vblank; // disable vblank interrupt handler
 	g_spriteBuffer[g_spriteUpdates++] = oa;
 	REG_IE |= Int_vblank; // enable vblank interrupt handler

src/nostalgia/core/gba/irq.hpp

@@ -26,3 +26,9 @@ constexpr uint16_t Int_input  = 1 << 14; // gamepad
 constexpr uint16_t Int_cart   = 1 << 15; // cartridge removed
 
 }
+
+extern "C" {
+
+void nostalgia_core_wfi();
+
+}

src/nostalgia/core/gba/irq.s

@@ -1,5 +1,5 @@
 //
-// Copyright 2016 - 2020 gtalent2@gmail.com
+// Copyright 2016 - 2020 gary@drinkingtea.net
 //
 // This Source Code Form is subject to the terms of the Mozilla Public
 // License, v. 2.0. If a copy of the MPL was not distributed with this
@@ -16,7 +16,7 @@
 .extern nostalgia_core_isr_timer2
 .extern nostalgia_core_isr_timer3
 
-.equ REG_IFBIOS,         0x03fffff8
+.equ REG_IFBIOS,         0x03007ff8
 
 .equ REG_IE,             0x04000200
 .equ REG_IF,             0x04000202
@@ -54,51 +54,59 @@ isr:
 	strh r1, [r0, #2]
 	ldr r0, =#REG_IFBIOS
 	// Acknowledge IRQ in REG_IFBIOS
-	ldrh r2, [r0] // r2 becomes REG_IFBIOS value
+	ldr r2, [r0] // r2 becomes REG_IFBIOS value
 	orr r2, r2, r1
-	strh r2, [r0]
+	str r2, [r0]
 	// done with r2 as IFBIOS value
-	// done with r0 as REG_IE
-
-	// clear IME to disable interrupts
-	ldr r2, =#REG_IME
-	mov r0, #0
-	str r0, [r2]
-
-	// enter system mode
-	mrs r0, cpsr
-	bic r0, r0, #0xDF
-	orr r0, r0, #0x1F
-	msr cpsr, r0
-
-	push {lr}
-	ldr lr, =isr_end
+	// done with r0 as REG_IFBIOS
 
 	////////////////////////////////////////////////////
 	// Interrupt Table Begin                          //
 	////////////////////////////////////////////////////
 
 	cmp r1, #Int_vblank
-	beq nostalgia_core_isr_vblank
+	ldreq r0, =nostalgia_core_isr_vblank
+	beq isr_call_handler
 
 	cmp r1, #Int_timer0
-	beq nostalgia_core_isr_timer0
+	ldreq r0, =nostalgia_core_isr_timer0
+	beq isr_call_handler
 
 	cmp r1, #Int_timer1
-	beq nostalgia_core_isr_timer1
+	ldreq r0, =nostalgia_core_isr_timer1
+	beq isr_call_handler
 
 	cmp r1, #Int_timer2
-	beq nostalgia_core_isr_timer2
+	ldreq r0, =nostalgia_core_isr_timer2
+	beq isr_call_handler
 
 	cmp r1, #Int_timer3
-	beq nostalgia_core_isr_timer3
+	ldreq r0, =nostalgia_core_isr_timer3
+	beq isr_call_handler
 
 	////////////////////////////////////////////////////
 	// Interrupt Table End                            //
 	////////////////////////////////////////////////////
 
-isr_end:
-	// restore lr from before the Interrupt Table
+	b isr_end
+
+isr_call_handler:
+	// clear IME to disable interrupts
+	ldr r2, =#REG_IME
+	mov r1, #0
+	str r1, [r2]
+
+	// enter system mode
+	mrs r1, cpsr
+	bic r1, r1, #0xDF
+	orr r1, r1, #0x1F
+	msr cpsr, r1
+
+	push {lr}
+	ldr lr, =isr_restore
+	bx r0
+
+isr_restore:
 	pop {lr}
 
 	// re-enter irq mode
@@ -112,6 +120,8 @@ isr_end:
 	mov r0, #1
 	str r0, [r2]
 
+isr_end:
+
 	bx lr
 
 // vim: ft=armv4

src/nostalgia/core/gba/panic.cpp

@@ -6,8 +6,13 @@
  * file, You can obtain one at http://mozilla.org/MPL/2.0/.
  */
 
-#include "../core.hpp"
-#include "../gfx.hpp"
+#include <ox/std/memops.hpp>
+
+#include <nostalgia/core/core.hpp>
+#include <nostalgia/core/gfx.hpp>
+
+#include "addresses.hpp"
+#include "bios.hpp"
 
 namespace ox {
 
@@ -16,15 +21,20 @@ using namespace nostalgia::core;
 void panic(const char*, int, const char *msg, ox::Error err) {
 	oxIgnoreError(initGfx(nullptr));
 	oxIgnoreError(initConsole(nullptr));
+	// enable only BG 0
+	REG_DISPCTL = 0x0100;
+	clearTileLayer(nullptr, 0);
 	ox::BString<23> serr = "Error code: ";
 	serr += err;
-	puts(nullptr, 32 + 0,  1, "SADNESS...");
-	puts(nullptr, 32 + 0,  4, "UNEXPECTED STATE:");
+	puts(nullptr, 32 + 1,  1, "SADNESS...");
+	puts(nullptr, 32 + 1,  4, "UNEXPECTED STATE:");
 	puts(nullptr, 32 + 2,  6, msg);
-	puts(nullptr, 32 + 2,  7, serr.c_str());
-	puts(nullptr, 32 + 0, 10, "PLEASE RESTART THE SYSTEM");
-	// TODO: properly end program execution, this wastes power
-	while (1);
+	puts(nullptr, 32 + 2,  8, serr.c_str());
+	puts(nullptr, 32 + 1, 15, "PLEASE RESTART THE SYSTEM");
+	// disable interrupts and wait for interrupt, halt and stop seem to have
+	// issues in mGBA
+	REG_IME = 0;
+	nostalgia_core_wfi();
 }
 
 }

src/nostalgia/core/gfx.hpp

@@ -125,6 +125,8 @@ void puts(Context *ctx, int column, int row, const char *str);
 
 void setTile(Context *ctx, int layer, int column, int row, uint8_t tile);
 
+void clearTileLayer(Context*, int layer);
+
 void setSprite(unsigned idx, unsigned x, unsigned y, unsigned tileIdx);
 
 }