From 7c24e9a9b02b04dcaf9507acb94091ea70a2c02d Mon Sep 17 00:00:00 2001
From: Xavi Del Campo <xavi.dcr@tutanota.com>
Date: Fri, 31 Jan 2020 10:32:23 +0100
Subject: Imported pristine psxsdk-20190410 from official repo

---
 libpsx/src/exception.c | 178 +++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 178 insertions(+)
 create mode 100644 libpsx/src/exception.c

(limited to 'libpsx/src/exception.c')

diff --git a/libpsx/src/exception.c b/libpsx/src/exception.c
new file mode 100644
index 0000000..6ecabb2
--- /dev/null
+++ b/libpsx/src/exception.c
@@ -0,0 +1,178 @@
+/**
+ * exception.c
+ *
+ * Exception handling code (part 2)
+ */
+ 
+ #include <stdio.h>
+ #include <stdlib.h>
+ #include <psx.h>
+ 
+#define DICR			*((unsigned int*)0x1f8010f4)
+#define IPENDING		*((volatile unsigned int*)0x1f801070)
+#define IMASK			*((volatile unsigned int*)0x1f801074)
+
+void __psxsdk_exception_manager();
+
+void (*_EXC_vblank_handler)();
+void (*_EXC_cdrom_handler)();
+void (*_EXC_sio_handler)(unsigned char *data);
+void (*_EXC_dma_handler)();
+unsigned int _EXC_vblank_handler_set;
+unsigned int _EXC_cdrom_handler_set;
+unsigned int _EXC_sio_handler_set;
+unsigned int _EXC_dma_handler_set;
+
+volatile int __psxsdk_gpu_dma_finished;
+
+void __psxsdk_real_exception_handler()
+{
+	unsigned int Cause = get_cop0_register(COP0_CAUSE);
+	unsigned int Cause_excCode = (Cause >> 2) & 31;
+	unsigned int Cause_IP = (Cause >> 8) & 255; 
+	unsigned int SR = get_cop0_register(COP0_SR);
+	unsigned int SR_IM = (SR >> 8) & 255;
+	int i;
+/*	unsigned int oldSR = SR;
+	unsigned int psxIP = IPENDING;
+	unsigned int psxIM = IMASK;
+	unsigned int sio_data;*/
+	
+	if(Cause_excCode == 0) // interrupt generated the exception
+	{
+		/*for(i = 0; i < 8; i++)
+		{
+			if((Cause_IP & (1<<i)) && (SR_IM & (1<<i)))
+			{
+				SR ^= 1<<(i+8);
+				set_cop0_register(COP0_SR, SR);
+				
+				switch(i)
+				{
+					case 2: // PSX Interrupt controller
+					//	program_vblank_handler();
+					break;
+				}
+			}
+		}*/
+		
+		if((Cause_IP & (1<<2)) && (SR_IM & (1<<2)))
+		{
+			Cause ^= 1<<10;
+			set_cop0_register(COP0_CAUSE, Cause);
+			//SR ^= 1<<10;
+			//set_cop0_register(COP0_SR, SR);
+
+			//while(IPENDING != 0)
+			{			
+				for(i = 0; i < 11; i++)
+				{
+					if(IPENDING & (1<<i))
+					{
+				//		printf("IP = %x\n", IPENDING);
+// Very interesting, when reading joypad status the PCSXR emulator sets in IPENDING that IRQ7 is pending even
+// if it is not enabled in IMASK! That is insane, but it can be easily worked around.
+// So we are going to disable pending bits for IRQs in IPENDING in any case, even if the in IRQ at hand was
+// not enabled in IMASK.
+						
+						IPENDING ^= 1 << i;
+						
+						if(IMASK & (1<<i))
+						{
+					//		printf("IM = %x\n", IMASK);
+							
+							switch(i)
+							{
+								case 0: // VBLANK					
+							//		if(!(GPU_CONTROL_PORT & (1<<0x1c)))
+							//			GPU_CONTROL_PORT = 0x02000000;
+								
+								// Execute the user-supplied VBlank handler.	
+									if(_EXC_vblank_handler_set)
+										_EXC_vblank_handler();
+								break;
+								case 2:
+							/*		if(_EXC_cdrom_handler_set)
+										_EXC_cdrom_handler();*/
+								break;
+								case 3: // DMA
+								// Execute the user-supplied DMA handler.	
+									if(_EXC_dma_handler_set)
+										_EXC_dma_handler();
+								break;
+								case 8:
+								//while(!(SIO_STAT & 2))
+								//sio_data = SIO_RX_DATA;
+							
+								//_EXC_sio_handler((unsigned char*)&sio_data);
+						
+							//	SIO_CTRL |= SIOCTRL_ACK;
+								break;
+							}
+						}
+					}
+				}
+			}
+		}		
+	}
+}
+ 
+static void __psxsdk_dma_handler()
+{
+	unsigned int s_dicr = DICR;
+	unsigned char irq = (s_dicr >> 24) & 127;
+	
+	if(irq & (1<<2)) // GPU
+		__psxsdk_gpu_dma_finished = 1;
+		
+	// Acknowledge
+	DICR = s_dicr;
+	
+	// Waste some cycles, so that the acknowledgement is reported
+//	int x;
+	
+//	for(x = 0; x < 1000; x++);
+}
+
+extern void _internal_cdromlib_callback();
+
+ void __PSX_Init_NoBios()
+ {
+	_EXC_vblank_handler = NULL;
+	_EXC_cdrom_handler = _internal_cdromlib_callback;
+	_EXC_dma_handler = __psxsdk_dma_handler;
+	_EXC_sio_handler = NULL;
+	 
+	_EXC_vblank_handler_set = 0;
+	_EXC_cdrom_handler_set = 0;
+	_EXC_dma_handler_set = 1;
+	_EXC_sio_handler_set = 0;
+	 
+ 	IMASK = 0; // Clear Mask
+	IPENDING = 0; // Clear pending interrupts
+
+// Disable interrupts	 
+	 
+	set_cop0_register(COP0_SR, 0);
+	
+// Change exception vector to point to our exception manager	 
+	 
+	*((unsigned int*)0x80000080) = 0x08000000 | ((((unsigned int)__psxsdk_exception_manager)>>2) & 0x3FFFFFF);
+	*((unsigned int*)0x80000084) = 0;
+	
+	
+// Enable interrupt generation, and interrupt 2 (PlayStation Interrupt Controller)
+	set_cop0_register(COP0_SR, (1<<10) | 1);
+
+// Enable VBlank, CDROM and DMA IRQs (on PlayStation Interrupt Controller)
+	IMASK = 1 | /* CDROM */ /*4 |*/ 8;
+
+// Set DMA channel priority
+	DPCR = 0x07654321;
+	
+// Enable DMA IRQ master, and IRQ generation for DMA channel 2 (GPU)
+	DICR = (1<<23) | (1<<(16+2));
+
+// Setup variables
+	 __psxsdk_gpu_dma_finished = 1;
+}
-- 
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