source/m68k/readme.txt

@@ -0,0 +1,315 @@
+                                    MUSASHI
+                                    =======
+
+                                  Version 3.3
+
+             A portable Motorola M680x0 processor emulation engine.
+            Copyright 1998-2001 Karl Stenerud.  All rights reserved.
+
+
+
+INTRODUCTION:
+------------
+
+Musashi is a Motorola 68000, 68010, 68EC020, and 68020 emulator written in C.
+This emulator was written with two goals in mind: portability and speed.
+
+The emulator is written to ANSI C specifications with the exception that I use
+inline functions.  This is not compliant to the ANSI spec, but will be
+compliant to the ANSI C9X spec.
+
+It has been successfully running in the MAME project (www.mame.net) for over 2
+years and so has had time to mature.
+
+
+
+LICENSE AND COPYRIGHT:
+---------------------
+
+The Musashi M680x0 emulator is copyright 1998-2001 Karl Stenerud.
+
+The source code included in this archive is provided AS-IS, free for any
+non-commercial purpose.
+
+If you build a program using this core, please give credit to the author.
+
+If you wish to use this core in a commercial environment, please contact
+the author to discuss commercial licensing.
+
+
+
+AVAILABILITY:
+------------
+The latest version of this code can be obtained at:
+http://kstenerud.cjb.net
+
+
+
+CONTACTING THE AUTHOR:
+---------------------
+I can be reached at kstenerud@mame.net
+
+
+
+BASIC CONFIGURATION:
+-------------------
+The basic configuration will give you a standard 68000 that has sufficient
+functionality to work in a primitive environment.
+
+This setup assumes that you only have 1 device interrupting it, that the
+device will always request an autovectored interrupt, and it will always clear
+the interrupt before the interrupt service routine finishes (but could
+possibly re-assert the interrupt).
+You will have only one address space, no tracing, and no instruction prefetch.
+
+To implement the basic configuration:
+
+- Open m68kconf.h and verify that the settings for INLINE and DECL_SPEC will
+  work with your compiler. (They are set for gcc)
+
+- In your host program, implement the following functions:
+    unsigned int  m68k_read_memory_8(unsigned int address);
+    unsigned int  m68k_read_memory_16(unsigned int address);
+    unsigned int  m68k_read_memory_32(unsigned int address);
+    void m68k_write_memory_8(unsigned int address, unsigned int value);
+    void m68k_write_memory_16(unsigned int address, unsigned int value);
+    void m68k_write_memory_32(unsigned int address, unsigned int value);
+
+- In your host program, be sure to call m68k_pulse_reset() once before calling
+  any of the other functions as this initializes the core.
+
+- Use m68k_execute() to execute instructions and m68k_set_irq() to cause an
+  interrupt.
+
+
+
+ADDING PROPER INTERRUPT HANDLING:
+--------------------------------
+The interrupt handling in the basic configuration doesn't emulate the
+interrupt acknowledge phase of the CPU and automatically clears an interrupt
+request during interrupt processing.
+While this works for most systems, you may need more accurate interrupt
+handling.
+
+To add proper interrupt handling:
+
+- In m68kconf.h, set M68K_EMULATE_INT_ACK to OPT_SPECIFY_HANDLER
+
+- In m68kconf.h, set M68K_INT_ACK_CALLBACK(A) to your interrupt acknowledge
+  routine
+
+- Your interrupt acknowledge routine must return an interrupt vector,
+  M68K_INT_ACK_AUTOVECTOR, or M68K_INT_ACK_SPURIOUS.  most m68k
+  implementations just use autovectored interrupts.
+
+- When the interrupting device is satisfied, you must call m68k_set_irq(0) to
+  remove the interrupt request.
+
+
+
+MULTIPLE INTERRUPTS:
+-------------------
+The above system will work if you have only one device interrupting the CPU,
+but if you have more than one device, you must do a bit more.
+
+To add multiple interrupts:
+
+- You must make an interrupt arbitration device that will take the highest
+  priority interrupt and encode it onto the IRQ pins on the CPU.
+
+- The interrupt arbitration device should use m68k_set_irq() to set the
+  highest pending interrupt, or 0 for no interrupts pending.
+
+
+
+SEPARATE IMMEDIATE AND PC-RELATIVE READS:
+----------------------------------------
+You can write faster memory access functions if you know whether you are
+fetching from ROM or RAM.  Immediate reads are always from the program space
+(Always in ROM unless it is running self-modifying code).
+This will also separate the pc-relative reads, since some systems treat
+PROGRAM mode reads and DATA mode reads differently (for program encryption,
+for instance).  See the section below (ADDRESS SPACE) for an explanation of
+PROGRAM and DATA mode.
+
+To enable separate reads:
+
+- In m68kconf.h, turn on M68K_SEPARATE_READS.
+
+- In your host program, implement the following functions:
+    unsigned int  m68k_read_immediate_16(unsigned int address);
+    unsigned int  m68k_read_immediate_32(unsigned int address);
+
+    unsigned int  m68k_read_pcrelative_8(unsigned int address);
+    unsigned int  m68k_read_pcrelative_16(unsigned int address);
+    unsigned int  m68k_read_pcrelative_32(unsigned int address);
+
+- If you need to know the current PC (for banking and such), set
+  M68K_MONITOR_PC to OPT_SPECIFY_HANDLER, and set M68K_SET_PC_CALLBACK(A) to
+  your routine.
+
+
+
+ADDRESS SPACES:
+--------------
+Most systems will only implement one address space, placing ROM at the lower
+addresses and RAM at the higher.  However, there is the possibility that a
+system will implement ROM and RAM in the same address range, but in different
+address spaces, or will have different mamory types that require different
+handling for the program and the data.
+
+The 68k accomodates this by allowing different program spaces, the most
+important to us being PROGRAM and DATA space.  Here is a breakdown of
+how information is fetched:
+
+- All immediate reads are fetched from PROGRAM space.
+
+- All PC-relative reads are fetched from PROGRAM space.
+
+- The initial stack pointer and program counter are fetched from PROGRAM space.
+
+- All other reads (except for those from the moves instruction for 68020)
+   are fetched from DATA space.
+
+The m68k deals with this by encoding the requested address space on the
+function code pins:
+
+                       FC
+    Address Space      210
+    ------------------ ---
+    USER DATA          001
+    USER PROGRAM       010
+    SUPERVISOR DATA    101
+    SUPERVISOR PROGRAM 110
+    CPU SPACE          111 <-- not emulated in this core since we emulate
+                               interrupt acknowledge in another way.
+
+Problems arise here if you need to emulate this distinction (if, for example,
+your ROM and RAM are at the same address range, with RAM and ROM enable
+wired to the function code pins).
+
+There are 2 ways to deal with this situation using Musashi:
+
+1. If you only need the distinction between PROGRAM and DATA (the most common),
+   you can just separate the reads (see the preceeding section).  This is the
+   faster solution.
+
+2. You can emulate the function code pins entirely.
+
+To emulate the function code pins:
+
+- In m68kconf.h, set M68K_EMULATE_FC to OPT_SPECIFY_HANDLER and set
+  M68K_SET_FC_CALLBACK(A) to your function code handler function.
+
+- Your function code handler should select the proper address space for
+  subsequent calls to m68k_read_xx (and m68k_write_xx for 68010+).
+
+Note: immediate reads are always done from program space, so technically you
+      don't need to implement the separate immediate reads, although you could
+      gain more speed improvements leaving them in and doing some clever
+      programming.
+
+
+
+USING DIFFERENT CPU TYPES:
+-------------------------
+The default is to enable only the 68000 cpu type.  To change this, change the
+settings for M68K_EMULATE_010 etc in m68kconf.h.
+
+To set the CPU type you want to use:
+
+- Make sure it is enabled in m68kconf.h.  Current switches are:
+    M68K_EMULATE_010
+    M68K_EMULATE_EC020
+    M68K_EMULATE_020
+
+- In your host program, call m68k_set_cpu_type() and then call
+  m68k_pulse_reset().  Valid CPU types are:
+    M68K_CPU_TYPE_68000,
+    M68K_CPU_TYPE_68010,
+    M68K_CPU_TYPE_68EC020,
+    M68K_CPU_TYPE_68020
+
+
+
+CLOCK FREQUENCY:
+---------------
+In order to emulate the correct clock frequency, you will have to calculate
+how long it takes the emulation to execute a certain number of "cycles" and
+vary your calls to m68k_execute() accordingly.
+As well, it is a good idea to take away the CPU's timeslice when it writes to
+a memory-mapped port in order to give the device it wrote to a chance to
+react.
+
+You can use the functions m68k_cycles_run(), m68k_cycles_remaining(),
+m68k_modify_timeslice(), and m68k_end_timeslice() to do this.
+Try to use large cycle values in your calls to m68k_execute() since it will
+increase throughput.  You can always take away the timeslice later.
+
+
+
+MORE CORRECT EMULATION:
+----------------------
+You may need to enable these in order to properly emulate some of the more
+obscure functions of the m68k:
+
+- M68K_EMULATE_BKPT_ACK causes the CPU to call a breakpoint handler on a BKPT
+  instruction
+
+- M68K_EMULATE_TRACE causes the CPU to generate trace exceptions when the
+  trace bits are set
+
+- M68K_EMULATE_RESET causes the CPU to call a reset handler on a RESET
+  instruction.
+
+- M68K_EMULATE_PREFETCH emulates the 4-word instruction prefetch that is part
+  of the 68000/68010 (needed for Amiga emulation).
+
+- call m68k_pulse_halt() to emulate the HALT pin.
+
+
+
+CONVENIENCE FUNCTIONS:
+---------------------
+These are in here for programmer convenience:
+
+- M68K_INSTRUCTION_HOOK lets you call a handler before each instruction.
+
+- M68K_LOG_ENABLE and M68K_LOG_1010_1111 lets you log illegal and A/F-line
+  instructions.
+
+
+
+MULTIPLE CPU EMULATION:
+----------------------
+The default is to use only one CPU.  To use more than one CPU in this core,
+there are some things to keep in mind:
+
+- To have different cpus call different functions, use OPT_ON instead of
+  OPT_SPECIFY_HANDLER, and use the m68k_set_xxx_callback() functions to set
+  your callback handlers on a per-cpu basis.
+
+- Be sure to call set_cpu_type() for each CPU you use.
+
+- Use m68k_set_context() and m68k_get_context() to switch to another CPU.
+
+
+
+LOAD AND SAVE CPU CONTEXTS FROM DISK:
+------------------------------------
+You can use them68k_load_context() and m68k_save_context() functions to load
+and save the CPU state to disk.
+
+
+
+GET/SET INFORMATION FROM THE CPU:
+--------------------------------
+You can use m68k_get_reg() and m68k_set_reg() to gain access to the internals
+of the CPU.
+
+
+
+EXAMPLE:
+-------
+
+I have included a file example.zip that contains a full example.

source/sound/sound.c

@@ -18,7 +18,7 @@ extern void *myFM;
 void sound_init(void)
 {
 	/* Timers run at half the YM2612 input clock */
-	float clock = ((CPU_Clock / 1000000.0) / 7.0) / 2.0;
+	float clock = ((Master_Clock / 1000000.0) / 7.0) / 2.0;
 	int i;
 
 	/* Make Timer A table */

source/system.c

@@ -32,7 +32,7 @@ uint32 count_z80  = 0;
 uint16 misc68Kcycles   = 488;
 uint16 miscZ80cycles   = 228;
 uint16 lines_per_frame = 262;
-double CPU_Clock    = (double)CLOCK_NTSC;
+double Master_Clock    = (double)CLOCK_NTSC;
 void *myFM = NULL;
 static int sound_tbl[312];
 static int sound_inc[312];
@@ -81,8 +81,8 @@ extern uint8 hq_fm;
 int audio_init (int rate)
 {
 	int i;
-	int vclk = (int)(CPU_Clock / 7.0);  /* 68000 and YM2612 clock */
-	int zclk = (int)(CPU_Clock / 15.0); /* Z80 and SN76489 clock  */
+	int vclk = (int)(Master_Clock / 7.0);  /* 68000 and YM2612 clock */
+	int zclk = (int)(Master_Clock / 15.0); /* Z80 and SN76489 clock  */
 
 	/* Clear the sound data context */
 	memset (&snd, 0, sizeof (snd));
@@ -146,9 +146,9 @@ void system_init (void)
 	/* PAL or NTSC timings */
 	vdp_rate        = (vdp_pal) ? 50 : 60;
 	lines_per_frame = (vdp_pal) ? 313 : 262;
-	CPU_Clock = (vdp_pal) ? (double)CLOCK_PAL : (double)CLOCK_NTSC;
-	miscZ80cycles = (vdp_pal) ? 227 : 228;
-	misc68Kcycles = (vdp_pal) ? 487 : 488;
+	Master_Clock = (vdp_pal) ? (double)CLOCK_PAL : (double)CLOCK_NTSC;
+	miscZ80cycles = (vdp_pal) ? 227 : 228; /* Master_Clock / 13 / vdp_rate / lines_per_frame */
+	misc68Kcycles = (vdp_pal) ? 486 : 488; /* Master_Clock / 7  / vdp_rate / lines_per_frame */
 
 	gen_init ();
 	vdp_init ();
@@ -289,7 +289,7 @@ int system_frame (int do_skip)
 			} 
 		}
 
-	  status &= 0xFFFB; // HBlank = 0
+	    status &= 0xFFFB; // HBlank = 0
 
 		/* Process end of line */
 		m68k_run(aim_m68k);