Rewrite libpsxetc in C, add ResetCallback()

9 files changed, 235 insertions, 438 deletions

diff --git a/libpsn00b/include/psxapi.h b/libpsn00b/include/psxapi.h
index 1bdbdbf..5d1097e 100644
--- a/libpsn00b/include/psxapi.h
+++ b/libpsn00b/include/psxapi.h
@@ -224,9 +224,10 @@ int Exec(struct EXEC *exec, int argc, char **argv);
 void FlushCache(void);
 
 void b_setjmp(struct JMP_BUF *buf);
-void b_longjmp(struct JMP_BUF *buf, int param);
+void b_longjmp(const struct JMP_BUF *buf, int param);
 void SetDefaultExitFromException(void);
-void SetCustomExitFromException(struct JMP_BUF *buf);
+void SetCustomExitFromException(const struct JMP_BUF *buf);
+void ReturnFromException(void);
 
 int GetSystemInfo(int index);
 void *GetB0Table(void);
diff --git a/libpsn00b/include/psxetc.h b/libpsn00b/include/psxetc.h
index a55e593..24485d9 100644
--- a/libpsn00b/include/psxetc.h
+++ b/libpsn00b/include/psxetc.h
@@ -1,15 +1,25 @@
-#ifndef _PSXETC_H
-#define _PSXETC_H
+/*
+ * PSn00bSDK interrupt management library
+ * (C) 2019-2022 Lameguy64, spicyjpeg - MPL licensed
+ */
+
+#ifndef __PSXETC_H
+#define __PSXETC_H
+
+/* Public API */
 
 #ifdef __cplusplus
 extern "C" {
 #endif
 
-// Interrupt callback functions
-void *DMACallback(int dma, void (*func)(void));
 void *InterruptCallback(int irq, void (*func)(void));
-void *GetInterruptCallback(int irq);				// Original
-void RestartCallback();
+void *GetInterruptCallback(int irq);
+void *DMACallback(int dma, void (*func)(void));
+void *GetDMACallback(int dma);
+
+int ResetCallback(void);
+void RestartCallback(void);
+void StopCallback(void);
 
 #ifdef __cplusplus
 }
diff --git a/libpsn00b/psxetc/dmacallback.s b/libpsn00b/psxetc/dmacallback.s
deleted file mode 100644
index 8ea8ec0..0000000
--- a/libpsn00b/psxetc/dmacallback.s
+++ /dev/null
@@ -1,191 +0,0 @@
-.set noreorder
-
-.include "hwregs_a.h"
-
-.section .text
-
-.global DMACallback
-.type DMACallback, @function
-DMACallback:
-
-	# a0 - DMA channel
-	# a1 - Callback function
-	
-	addiu	$sp, -8
-	sw		$ra, 0($sp)
-
-	beqz	$a1, .Lremove_cb		# Remove callback if function is NULL
-	nop
-	
-	addiu	$sp, -8					# Install IRQ handler for DMA handler
-	sw		$a0, 0($sp)				# if not set installed yet
-	sw		$a1, 4($sp)
-	
-	jal		GetInterruptCallback
-	li		$a0, 3
-	
-	bnez	$v0, .Lskip_install
-	nop
-	
-	la		$a1, _dma_handler
-	jal		InterruptCallback
-	li		$a0, 3
-
-.Lskip_install:
-	
-	lw		$a0, 0($sp)
-	lw		$a1, 4($sp)
-	addiu	$sp, 8
-	
-	la		$v0, _dma_func_table
-	sll		$v1, $a0, 2
-	addu	$v0, $v1
-	lw		$v1, 0($v0)
-	sw		$a1, 0($v0)
-	sw		$v1, 4($sp)
-	
-	lui		$a2, IOBASE
-	
-	lw		$v0, DMA_DICR($a2)		# Enable DMA interrupt
-	lui		$v1, 0x1
-	sll		$v1, $a0
-	or		$v0, $v1
-	lui		$v1, 0x80
-	or		$v0, $v1
-	sw		$v0, DMA_DICR($a2)
-	
-	b		.Lskip_remove
-	nop
-	
-.Lremove_cb:
-
-	la		$v0, _dma_func_table	# Set callback address
-	sll		$v1, $a0, 2
-	addu	$v0, $v1
-	lw		$v1, 0($v0)
-	sw		$a1, 0($v0)
-	sw		$v1, 4($sp)
-	
-	lui		$a2, IOBASE				# Disable DMA interrupt
-	lw		$v0, DMA_DICR($a2)
-	lui		$v1, 0x1
-	sll		$v1, $a0
-	.set noat
-	addiu	$at, $0, -1
-	xor		$v1, $at
-	and		$v0, $v1
-	lui		$v1, 0x7f00
-	xor		$v1, $at
-	and		$v0, $v1
-	.set at
-	sw		$v0, DMA_DICR($a2)
-	
-	jal		_dma_has_cb				# Check if callbacks are present
-	nop
-	bnez	$v0, .Lskip_remove
-	nop
-	sw		$0 , DMA_DICR($a2)
-	
-	jal		GetInterruptCallback	# Check if callback is the DMA handler
-	li		$a0, 3
-	la		$v1, _dma_handler
-	bne		$v0, $v1, .Lskip_remove
-	nop
-	
-	li		$a0, 3
-	jal		InterruptCallback
-	move	$a1, $0
-	
-.Lskip_remove:
-	
-	lw		$ra, 0($sp)
-	lw		$v0, 4($sp)
-	jr		$ra
-	addiu	$sp, 8
-
-	
-.type _dma_has_cb, @function
-_dma_has_cb:
-
-	la		$v1, _dma_func_table
-	li		$t0, 6
-	
-.Lscan_loop:
-
-	lw		$v0, 0($v1)
-	addiu	$v1, 4
-	bnez	$v0, .Lhas_cb
-	nop
-	
-	bgtz	$t0, .Lscan_loop
-	addiu	$t0, -1
-	
-	jr		$ra
-	move	$v0, $0
-	
-.Lhas_cb:
-
-	jr		$ra
-	li		$v0, 1
-	
-	
-.type _dma_handler, @function
-_dma_handler:
-
-	addiu	$sp, -12
-	sw		$ra, 0($sp)
-	sw		$s0, 4($sp)
-	sw		$s1, 8($sp)
-	
-	move	$s0, $0
-	la		$s1, _dma_func_table
-	
-.Lhandler_loop:
-
-	lui		$a0, IOBASE
-	lw		$v0, DMA_DICR($a0)
-	li		$v1, 24
-	addu	$v1, $s0
-	srl		$v0, $v1
-	andi	$v0, 0x1
-	
-	lw		$v1, 0($s1)
-	
-	beqz	$v0, .Lno_irq
-	addiu	$s1, 4
-	
-	beqz	$v1, .Lno_irq
-	nop
-	
-	jalr	$v1
-	nop
-	
-.Lno_irq:
-	
-	blt		$s0, 6, .Lhandler_loop
-	addi	$s0, 1
-	
-	lui		$a0, IOBASE
-	lw		$v0, DMA_DICR($a0)
-	nop
-	sw		$v0, DMA_DICR($a0)
-	
-	lw		$ra, 0($sp)
-	lw		$s0, 4($sp)
-	lw		$s1, 8($sp)
-	
-	jr		$ra
-	addiu	$sp, -12
-	
-	
-.section .data
-
-_dma_func_table:
-	.word	0
-	.word	0
-	.word	0
-	.word	0
-	.word	0
-	.word	0
-	.word	0
-	
\ No newline at end of file
diff --git a/libpsn00b/psxetc/getinterruptcallback.s b/libpsn00b/psxetc/getinterruptcallback.s
deleted file mode 100644
index 510447f..0000000
--- a/libpsn00b/psxetc/getinterruptcallback.s
+++ /dev/null
@@ -1,19 +0,0 @@
-.set noreorder
-
-.section .text
-
-.global GetInterruptCallback
-.type GetInterruptCallback, @function
-GetInterruptCallback:
-	
-	# a0 - Interrupt number
-	
-	la		$a1, _irq_func_table
-	sll		$a0, 2
-	addu	$a1, $a0
-	lw		$v0, 0($a1)
-	nop
-	jr		$ra
-	nop
-	
-	
\ No newline at end of file
diff --git a/libpsn00b/psxetc/interruptcallback.s b/libpsn00b/psxetc/interruptcallback.s
deleted file mode 100644
index 78e5e6e..0000000
--- a/libpsn00b/psxetc/interruptcallback.s
+++ /dev/null
@@ -1,48 +0,0 @@
-.set noreorder
-
-.include "hwregs_a.h"
-
-.section .text
-
-.global InterruptCallback
-.type InterruptCallback, @function
-InterruptCallback:
-
-	# a0 - Interrupt number
-	# a1 - Callback function
-
-	lui		$a2, IOBASE
-	
-	beqz	$a1, .Ldisable_irq
-	nop
-
-	lw		$v0, IRQ_MASK($a2)			# Enable interrupt mask
-	li		$v1, 1
-	sll		$v1, $a0
-	or		$v0, $v1
-
-	b		.Lcont
-	sw		$v0, IRQ_MASK($a2)
-	
-.Ldisable_irq:
-
-.set noat
-	lw		$v0, IRQ_MASK($a2)			# Disable interrupt mask
-	li		$v1, 1
-	sll		$v1, $a0
-	addiu	$at, $0 , -1
-	xor		$v1, $at
-.set at
-	and		$v0, $v1
-	sw		$v0, IRQ_MASK($a2)
-	
-.Lcont:
-
-	la		$a2, _irq_func_table		# Get address to IRQ function table
-	
-	sll		$v1, $a0, 2					# Compute the slot
-	addu	$v1, $a2, $v1
-	lw		$v0, 0($v1)					# Get old handler address
-	
-	jr		$ra							# Return and set new IRQ handler
-	sw		$a1, 0($v1)
diff --git a/libpsn00b/psxetc/interrupts.c b/libpsn00b/psxetc/interrupts.c
new file mode 100644
index 0000000..e5c4705
--- /dev/null
+++ b/libpsn00b/psxetc/interrupts.c
@@ -0,0 +1,214 @@
+/*
+ * PSn00bSDK interrupt management library
+ * (C) 2022 spicyjpeg - MPL licensed
+ */
+
+#include <stdint.h>
+#include <psxapi.h>
+#include <psxetc.h>
+#include <hwregs_c.h>
+
+#define NUM_IRQ_CHANNELS	11
+#define NUM_DMA_CHANNELS	7
+#define ISR_STACK_SIZE		0x1000
+
+/* Internal globals */
+
+static void (*_irq_handlers[NUM_IRQ_CHANNELS])(void) = { (void *) 0 };
+static void (*_dma_handlers[NUM_DMA_CHANNELS])(void) = { (void *) 0 };
+static int  _num_dma_handlers = 0;
+
+static uint32_t _saved_irq_mask, _saved_dma_dpcr, _saved_dma_dicr;
+static int _isr_installed = 0;
+
+/* Custom ISR jmp_buf */
+
+// The ISR and all functions called by it (thus, all callbacks registered using
+// InterruptCallback() and DMACallback()) use an independent stack, isolated
+// from the main thread's stack. As the size of this stack is limited, custom
+// callbacks shall keep the number of nested subroutine calls to a minimum and
+// avoid allocating large buffers (e.g. for receiving a sector from the CD
+// drive) on the stack.
+static uint8_t _isr_stack[ISR_STACK_SIZE];
+
+extern uint8_t _gp[];
+static void _global_isr(void);
+
+static const struct JMP_BUF _isr_jmp_buf = {
+	.ra = (uint32_t) &_global_isr,
+	.sp = (uint32_t) &_isr_stack[ISR_STACK_SIZE],
+	.fp = 0,
+	.s0 = 0,
+	.s1 = 0,
+	.s2 = 0,
+	.s3 = 0,
+	.s4 = 0,
+	.s5 = 0,
+	.s6 = 0,
+	.s7 = 0,
+	.gp = (uint32_t) _gp
+};
+
+/* Internal IRQ and DMA handlers */
+
+static void _global_isr(void) {
+	uint32_t stat = IRQ_STAT, mask = IRQ_MASK;
+
+	// Clear all IRQ flags in one shot. This is not the "proper" way to do it
+	// but it's much faster than clearing one flag at a time.
+	IRQ_STAT = ~mask;
+
+	//for (int i = 0; i < NUM_IRQ_CHANNELS; i++) {
+	for (int i = 0; stat; i++, stat >>= 1) {
+		if (!(stat & 1))
+			continue;
+
+		if (_irq_handlers[i])
+			_irq_handlers[i]();
+	}
+
+	ReturnFromException();
+}
+
+static void _global_dma_handler(void) {
+	uint32_t stat = DMA_DICR;
+
+	// Clear all DMA IRQ flags in one shot (note that flags are cleared by
+	// writing 1 to them rather than 0).
+	stat    &= 0x7fff0000;
+	DMA_DICR = stat;
+	stat   >>= 24;
+
+	//for (int i = 0; i < NUM_DMA_CHANNELS; i++) {
+		for (int i = 0; stat; i++, stat >>= 1) {
+		if (!(stat & 1))
+			continue;
+
+		if (_dma_handlers[i])
+			_dma_handlers[i]();
+	}
+}
+
+/* Callback registration API */
+
+void *InterruptCallback(int irq, void (*func)(void)) {
+	if ((irq < 0) || (irq >= NUM_IRQ_CHANNELS))
+		return 0;
+
+	void *old_callback = _irq_handlers[irq];
+	_irq_handlers[irq] = func;
+
+	// Enable or disable the IRQ in the IRQ_MASK register depending on whether
+	// the callback is being registered or removed.
+	if (func)
+		IRQ_MASK |= 1 << irq;
+	else
+		IRQ_MASK &= ~(1 << irq);
+
+	return old_callback;
+}
+
+void *GetInterruptCallback(int irq) {
+	if ((irq < 0) || (irq >= NUM_IRQ_CHANNELS))
+		return 0;
+
+	return _irq_handlers[irq];
+}
+
+void *DMACallback(int dma, void (*func)(void)) {
+	if ((dma < 0) || (dma >= NUM_DMA_CHANNELS))
+		return 0;
+
+	void *old_callback = _dma_handlers[dma];
+	_dma_handlers[dma] = func;
+
+	// Enable or disable the IRQ in the DMA_DICR register depending on whether
+	// the callback is being registered or removed. The main DMA IRQ dispatcher
+	// is also registered if this is the first DMA callback being configured,
+	// or disabled if it's the last one being removed.
+	if (func) {
+		DMA_DICR |= (0x10000 << dma) | (1 << 23);
+
+		if (!(_num_dma_handlers++))
+			InterruptCallback(3, &_global_dma_handler);
+	} else {
+		if (--_num_dma_handlers) {
+			DMA_DICR &= ~(0x10000 << dma);
+		} else {
+			DMA_DICR = 0;
+			InterruptCallback(3, 0);
+		}
+	}
+
+	return old_callback;
+}
+
+void *GetDMACallback(int dma) {
+	if ((dma < 0) || (dma >= NUM_DMA_CHANNELS))
+		return 0;
+
+	return _dma_handlers[dma];
+}
+
+/* Hook installation/removal API */
+
+int ResetCallback(void) {
+	if (_isr_installed)
+		return -1;
+
+	_saved_irq_mask = 0;
+	_saved_dma_dpcr = 0x03333333;
+	_saved_dma_dicr = 0;
+
+	_96_remove();
+	RestartCallback();
+	return 0;
+}
+
+void RestartCallback(void) {
+	if (_isr_installed)
+		return;
+
+	IRQ_STAT = 0;
+	IRQ_MASK = _saved_irq_mask;
+	DMA_DPCR = _saved_dma_dpcr;
+	DMA_DICR = _saved_dma_dicr;
+
+	// Install the ISR hook and prevent the kernel's internal handlers from
+	// automatically acknowledging SPI and timer IRQs.
+	SetCustomExitFromException(&_isr_jmp_buf);
+	ChangeClearPAD(0);
+	ChangeClearRCnt(0, 0);
+	ChangeClearRCnt(1, 0);
+	ChangeClearRCnt(2, 0);
+	ChangeClearRCnt(3, 0);
+
+	_isr_installed = 1;
+	ExitCriticalSection();
+}
+
+void StopCallback(void) {
+	if (!_isr_installed)
+		return;
+
+	// Save the state of IRQ and DMA registers, then reset them and undo the
+	// changes that were made to the kernel's state.
+	EnterCriticalSection();
+	_saved_irq_mask = IRQ_MASK;
+	_saved_dma_dpcr = DMA_DPCR;
+	_saved_dma_dicr = DMA_DICR;
+
+	IRQ_STAT = 0;
+	IRQ_MASK = 0;
+	DMA_DPCR = _saved_dma_dpcr & 0x07777777;
+	DMA_DICR = 0;
+
+	SetDefaultExitFromException();
+	ChangeClearPAD(1);
+	ChangeClearRCnt(0, 1);
+	ChangeClearRCnt(1, 1);
+	ChangeClearRCnt(2, 1);
+	ChangeClearRCnt(3, 1);
+
+	_isr_installed = 0;
+}
diff --git a/libpsn00b/psxetc/isr.s b/libpsn00b/psxetc/isr.s
deleted file mode 100644
index 440be50..0000000
--- a/libpsn00b/psxetc/isr.s
+++ /dev/null
@@ -1,107 +0,0 @@
-.set noreorder
-
-.include "hwregs_a.h"
-
-.set ISR_STACK_SIZE, 4096
-
-
-.section .text
-
-# Global ISR handler of PSn00bSDK
-
-.set at
-
-.type _global_isr, @function
-_global_isr:
-	
-.Lisr_loop:
-
-	#la		$gp, _gp					# Keep restoring GP since it gets
-										# changed elsewhere sometimes
-	
-	lui		$a0, IOBASE					# Get IRQ status
-	lw		$v0, IRQ_MASK($a0)
-	nop
-	
-	srl		$v0, $s1					# Check IRQ mask bit if set
-	andi	$v0, 0x1
-	
-	beqz	$v0, .Lno_irq				# Don't execute callback if IRQ not enabled
-	nop
-	
-	lw		$v0, IRQ_STAT($a0)
-	nop
-	srl		$v0, $s1					# Check IRQ status bit if set
-	andi	$v0, 0x1
-	beqz	$v0, .Lno_irq				# Don't execute callback if no IRQ
-	nop
-	
-	lw		$v1, 0($s0)					# Load IRQ callback function
-	nop
-	
-	lw		$v0, IRQ_STAT($a0)			# Acknowledge the IRQ (by writing a 0 bit)
-	li		$a1, 1
-	sll		$a1, $s1
-	addiu	$a2, $0 , -1
-	xor		$a1, $a2
-	sw		$a1, IRQ_STAT($a0)
-	
-	beqz	$v1, .Lno_irq				# Don't execute if callback is not set
-	nop
-
-	jalr	$v1							# Call interrupt handler
-	nop
-	
-.Lno_irq:
-
-	addiu	$s0, 4
-	
-	blt		$s1, 11, .Lisr_loop
-	addiu	$s1, 1
-
-	j		ReturnFromException
-	nop
-
-
-.section .data
-
-# Global ISR callback table
-
-.global _irq_func_table
-.type _irq_func_table, @object
-_irq_func_table:
-	.word	0
-	.word	0
-	.word	0
-	.word	0
-	.word	0
-	.word	0
-	.word	0
-	.word	0
-	.word	0
-	.word	0
-	.word	0
-	.word	0
-
-# Global ISR hook structure
-.global _custom_exit
-.type _custom_exit, @object
-_custom_exit:
-	.word _global_isr			# pc
-	.word _isr_stack+ISR_STACK_SIZE	# sp
-	.word 0						# fp
-	.word _irq_func_table		# s0
-	.word 0						# s1
-	.word 0						# s2
-	.word 0						# s3
-	.word 0						# s4
-	.word 0						# s5
-	.word 0						# s6
-	.word 0						# s7
-	.word _gp					# gp
-	
-# Global ISR stack
-#	.fill 1024
-#_custom_exit_stack:
-#	.fill 4
-.comm _isr_stack, ISR_STACK_SIZE+4
diff --git a/libpsn00b/psxetc/restartcallback.s b/libpsn00b/psxetc/restartcallback.s
deleted file mode 100644
index 036a5a0..0000000
--- a/libpsn00b/psxetc/restartcallback.s
+++ /dev/null
@@ -1,54 +0,0 @@
-.set noreorder
-
-.include "hwregs_a.h"
-
-.section .text
-
-.global RestartCallback
-.type RestartCallback, @function
-RestartCallback:
-
-	addiu	$sp, -4
-	sw		$ra, 0($sp)
-	
-	la		$a0, _custom_exit
-	jal		SetCustomExitFromException
-	addiu	$sp, -4
-	addiu	$sp, 4
-	
-	move	$a0, $0
-	jal		ChangeClearPAD
-	addiu	$sp, -4
-	addiu	$sp, 4
-	
-	li		$a0, 3
-	move	$a1, $0
-	jal		ChangeClearRCnt
-	addiu	$sp, -8
-	addiu	$sp, 8
-	
-	la		$a0, _irq_func_table
-	move	$a1, $0
-	move	$v0, $0
-	
-.Lcheck_cbs:							# Set up the interrupt masks
-	lw		$v1, 0($a0)
-	nop
-	beqz	$v1, .Lno_cb
-	addiu	$a0, 4
-	li		$v1, 1
-	sll		$v1, $a1
-	or		$v0, $v1
-.Lno_cb:
-	blt		$a1, 10, .Lcheck_cbs
-	addiu	$a1, 1
-	
-	lui		$a0, IOBASE
-	sw		$0 , IRQ_STAT($a0)
-	sw		$v0, IRQ_MASK($a0)
-	
-	lw		$ra, 0($sp)
-	addiu	$sp, 4
-	jr		$ra
-	nop
-	
\ No newline at end of file
diff --git a/libpsn00b/psxgpu/common.c b/libpsn00b/psxgpu/common.c
index 4591012..d338d93 100644
--- a/libpsn00b/psxgpu/common.c
+++ b/libpsn00b/psxgpu/common.c
@@ -58,23 +58,14 @@ static void _gpu_dma_handler(void) {
 void ResetGraph(int mode) {
 	// Perform some basic system initialization when ResetGraph() is called for
 	// the first time.
-	static int setup_done = 0;
-	if (!setup_done) {
+	if (!ResetCallback()) {
 		EnterCriticalSection();
-
-		DMA_DPCR = 0x03333333;
-		DMA_DICR = 0;
-		IRQ_MASK = 0;
-
 		InterruptCallback(0, &_vblank_handler);
 		DMACallback(2, &_gpu_dma_handler);
-		RestartCallback();
-		_96_remove();
 
 		_gpu_video_mode = (GPU_GP1 >> 20) & 1;
-		setup_done      = 1;
-
 		ExitCriticalSection();
+
 		printf("psxgpu: setup done, default mode is %s\n", _gpu_video_mode ? "PAL" : "NTSC");
 	}