From 5ac2e47a730e2347467193636083be4bb7213dbb Mon Sep 17 00:00:00 2001
From: Jeroen Domburg <git@j0h.nl>
Date: Fri, 3 Mar 2017 19:42:48 +0800
Subject: [PATCH] IWM faker. Need VIA now.

---
 Makefile |  2 +-
 emu.c    | 41 +++++++++++++++++++++++++++++++----------
 iwm.c    | 54 ++++++++++++++++++++++++++++++++++++++++++++++++++++++
 iwm.h    |  2 ++
 4 files changed, 88 insertions(+), 11 deletions(-)
 create mode 100644 iwm.c
 create mode 100644 iwm.h

diff --git a/Makefile b/Makefile
index 1575c75..37d3f37 100644
--- a/Makefile
+++ b/Makefile
@@ -1,6 +1,6 @@
 TARGET:=tme
 MUSASHI_GEN_SRC:=musashi/m68kops.c musashi/m68kopac.c musashi/m68kopdm.c musashi/m68kopnz.c
-OBJ:=$(MUSASHI_GEN_SRC:%.x=%.o) musashi/m68kcpu.o  main.o emu.o disp.o
+OBJ:=$(MUSASHI_GEN_SRC:%.x=%.o) musashi/m68kcpu.o  main.o emu.o disp.o iwm.o
 #musashi/m68kdasm.o
 CFLAGS=-Wall -I. -I./musashi -ggdb `sdl2-config --cflags`
 LDFLAGS=`sdl2-config --libs`
diff --git a/emu.c b/emu.c
index 056fde2..b5ea278 100644
--- a/emu.c
+++ b/emu.c
@@ -12,25 +12,42 @@
 unsigned char *macRom;
 unsigned char *macRam;
 
+void viaWrite(unsigned int addr, unsigned int val) {
+	printf("VIA write %x val %x\n", addr, val);
+}
+
+
+unsigned int viaRead(unsigned int addr) {
+	unsigned int val=0;
+	printf("VIA read %x val %x\n", addr, val);
+	return val;
+}
+
 int rom_remap;
 
 unsigned int  m68k_read_memory_8(unsigned int address) {
 	unsigned int ret;
 	unsigned int pc=m68k_get_reg(NULL, M68K_REG_PC);
-	if (rom_remap && address < 0x400000) {
-		ret=macRom[address & (TME_ROMSIZE-1)];
-	} else if (rom_remap && address > 0x600000 && address <= 0xA00000) {
+	if (address < 0x400000) {
+		if (rom_remap) {
+			ret=macRom[address & (TME_ROMSIZE-1)];
+		} else {
+			ret=macRam[address & (TME_RAMSIZE-1)];
+		}
+	} else if (address >= 0x600000 && address < 0xA00000) {
 		ret=macRam[address & (TME_RAMSIZE-1)];
-	} else if (address < 0x400000) {
-		ret=macRam[address & (TME_RAMSIZE-1)];
-	} else if (address>0x400000 && address<0x41FFFF) {
+	} else if (address >= 0x400000 && address<0x41FFFF) {
 		int romAdr=address-0x400000;
 		if (romAdr>TME_ROMSIZE) printf("PC %x:Huh? Read from ROM mirror (%x)\n", pc, address);
 		ret=macRom[romAdr&(TME_ROMSIZE-1)];
 //		rom_remap=0; //HACK
+	} else if (address >= 0xE80000 && address < 0xf00000) {
+		ret=viaRead((address>>8)&0xf);
+	} else if (address >= 0xc00000 && address < 0xe00000) {
+		ret=iwmRead((address>>8)&0xf);
 	} else {
 		printf("PC %x: Read from %x\n", pc, address);
-		ret=rand();
+		ret=0xaa;
 	}
 //	printf("Rd %x = %x\n", address, ret);
 	return ret;
@@ -40,8 +57,12 @@ void m68k_write_memory_8(unsigned int address, unsigned int value) {
 	unsigned int pc=m68k_get_reg(NULL, M68K_REG_PC);
 	if (address < 0x400000) {
 		macRam[address & (TME_RAMSIZE-1)]=value;
-	} else if (rom_remap && address > 0x600000 && address <= 0xA00000) {
+	} else if (address >= 0x600000 && address < 0xA00000) {
 		macRam[address & (TME_RAMSIZE-1)]=value;
+	} else if (address >= 0xE80000 && address < 0xf00000) {
+		viaWrite((address>>8)&0xf, value);
+	} else if (address >= 0xc00000 && address < 0xe00000) {
+		iwmWrite((address>>8)&0xf, value);
 	} else {
 		printf("PC %x: Write to %x: %x\n", pc, address, value);
 	}
@@ -60,13 +81,13 @@ void tmeStartEmu(void *rom) {
 	while(1) {
 		m68k_execute(8000000/60);
 		dispDraw(&macRam[0x1A700]);
-		printf("Int!\n");
+//		printf("Int!\n");
 //		m68k_set_irq(2);
 	}
 }
 
 
-//Mac uses an 68008, which has an external 8-bit bus. Hence, it should be okay to do everything using 8-bit
+//Mac uses an 68008, which has an external 16-bit bus. Hence, it should be okay to do everything using 16-bit
 //reads/writes.
 unsigned int  m68k_read_memory_32(unsigned int address) {
 	unsigned int ret;
diff --git a/iwm.c b/iwm.c
new file mode 100644
index 0000000..63438b3
--- /dev/null
+++ b/iwm.c
@@ -0,0 +1,54 @@
+#include <stdio.h>
+
+/*
+At the moment, this only emulates enough of the IWM to make the Plus boot.
+*/
+
+#define IWM_CA0		(1<<0)
+#define IWM_CA1		(1<<1)
+#define IWM_CA2		(1<<2)
+#define IWM_LSTRB	(1<<3)
+#define IWM_ENABLE	(1<<4)
+#define IWM_SELECT	(1<<5)
+#define IWM_Q6		(1<<6)
+#define IWM_Q7		(1<<7)
+
+int iwmLines, iwmModeReg;
+
+void iwmAccess(unsigned int addr) {
+	if (addr&1) {
+		iwmLines|=(1<<(addr>>1));
+	} else {
+		iwmLines&=~(1<<(addr>>1));
+	}
+}
+
+void iwmWrite(unsigned int addr, unsigned int val) {
+	iwmAccess(addr);
+	int reg=iwmLines&(IWM_Q7|IWM_Q6);
+	if (reg==0xC0) iwmModeReg=val;
+	printf("IWM write %x (iwm reg %x) val %x\n", addr, reg, val);
+}
+
+unsigned int iwmRead(unsigned int addr) {
+	unsigned int val=0;
+	iwmAccess(addr);
+	int reg=iwmLines&(IWM_Q7|IWM_Q6);
+	if (reg==0) {
+		//Data register
+		val=0;
+	} else if (reg==IWM_Q6) {
+		//Status register
+		if (iwmLines&IWM_ENABLE) val|=0x20; //enable
+		val|=iwmModeReg&0x1F;
+	} else if (reg==IWM_Q7) {
+		//Read handshake register
+		val=0xC0;
+	} else {
+		//Mode reg?
+		if (iwmLines&IWM_ENABLE) val|=0x20; //enable
+		val|=iwmModeReg&0x1F;
+	}
+	printf("IWM read %x (iwm reg %x) val %x\n", addr, reg, val);
+	return val;
+}
diff --git a/iwm.h b/iwm.h
new file mode 100644
index 0000000..557110c
--- /dev/null
+++ b/iwm.h
@@ -0,0 +1,2 @@
+void iwmWrite(unsigned int addr, unsigned int val);
+unsigned int iwmRead(unsigned int addr);