05a7f14f8d
git-svn-id: svn://svn.rockbox.org/rockbox/trunk@10950 a1c6a512-1295-4272-9138-f99709370657
182 lines
5 KiB
Text
182 lines
5 KiB
Text
This file describes how to use the Z80 processor emulation as a
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standalone module (without the ZX Spectrum emulation).
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===========================================================================
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You will need the following files:
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For the 'intel x86' assembly version:
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-------------------------------------
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z80.c z80.h z80_type.h i386step.S i386def.S i386op1.S i386op1x.S
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i386op2.S i386op2x.S i386op3.S i386op3x.S i386op4.S i386op5.S i386op6.S
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sp_to_s.c
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For the 'C' version:
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--------------------
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z80.c z80.h z80_type.h z80_step.c z80_def.h z80_ari.h z80optab.c z80optab.h
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z80_op1.c z80_op1x.c z80_op1.h z80_op2.c z80_op2x.c z80_op2.h
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z80_op3.c z80_op3x.c z80_op3.h z80_op4.c z80_op4x.c z80_op4.h
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z80_op5.c z80_op5.h z80_op6.c z80_op6.h
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===========================================================================
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Makefile rules:
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For the 'intel x86' assembly version:
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-------------------------------------
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CC = gcc
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AR = ar
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CPPFLAGS =
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CFLAGS = -Wall -O3
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CPP = $(CC) -E
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z80_i386_objs = z80.o i386emul.o
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libz80.a: $(z80_i386_objs)
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$(AR) cr libz80.a $(z80_i386_objs)
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i386emul.o: i386emul.s
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$(CC) -c $(CFLAGS) i386emul.s
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i386emul.s: i386emul.sp sp_to_s
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./sp_to_s < i386emul.sp > i386emul.s
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i386emul.sp: i386step.S
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$(CPP) $(CPPFLAGS) i386step.S > i386emul.sp
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sp_to_s: sp_to_s.o
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$(CC) -o sp_to_s $(LDFLAGS) sp_to_s.o
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.SUFFIXES:
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.SUFFIXES: .c .o
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.c.o:
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$(CC) -c $(CFLAGS) $(CPPFLAGS) $<
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For 'C' version:
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----------------
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CC = gcc
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AR = ar
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CPPFLAGS = -DZ80C
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CFLAGS = -Wall -O3 -fomit-frame-pointer -funroll-loops
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z80_c_objs = z80.o z80_step.o z80optab.o z80_op1.o z80_op2.o z80_op3.o \
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z80_op4.o z80_op5.o z80_op6.o
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libz80.a: $(z80_c_objs)
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$(AR) cr libz80.a $(z80_c_objs)
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.SUFFIXES:
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.SUFFIXES: .c .o
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.c.o:
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$(CC) -c $(CFLAGS) $(CPPFLAGS) $<
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===========================================================================
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The following functions are defined by libz80.a:
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void z80_init()
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---------------
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This function initializes the processor emulation. This must be called
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only once at the beginning of the program.
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int z80_step(int ticknum)
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-------------------------
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This function executes z80 instructions for 'ticknum' number of clock
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cycles. It returns the remaining number of ticks.
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NOTE: the remaining number of ticks is always zero or negative,
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meaning that exactly, or more than the given 'ticknum' clock cycles
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were executed. This is because WHOLE instructions are executed at a
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time.
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NOTE: HALT, LDDR, etc... do not count as one instruction, but as a
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series of instructions (e.g. HALT is a series of NOPs).
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void z80_reset()
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----------------
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This function resets the Z80 processor. This has the same effect as
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applying a pulse to the RESET input of the processor.
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NOTE: z80_init() does not reset the Z80, z80_reset() should be called
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after it.
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void z80_interrupt(int data)
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-----------------------------
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Causes a Maskable Interrupt. Interrupt mode 1 and 2 are emulated
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correctly, in interrupt mode 2 'data' is used in the address
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calculation. In interrupt mode 0, it is assumed (as on the ZX
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Spectrum) that 0xFF is on the data bus, and always RST 38 is
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generated.
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NOTE: It is not emulated, that in the instruction after EI no
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interrupt can be generated.
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void z80_nmi()
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--------------
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Causes a Non Maskable Interrupt.
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===========================================================================
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Accessing the memory, the I/O ports and the Z80 processor's state
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(i.e. registers, etc...)
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To use the functions above and the variables below, include the
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"z80.h" include file.
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Memory
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------
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The memory is stored in the z80_proc.mem[] byte array, which has a
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size of 65536. By default it is all RAM. To make parts of it read
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only, you have to redefine the appropriate macros in i386step.S and/or
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z80_def.h. (These macros are sorounded by #ifdef SPECT_MEM, #else,
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#endif statements.)
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The memory is initialised to random data. You must fill it in before
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starting the emulation, but AFTER the call to z80_init().
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I/O
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---
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The input port values are stored in z80_inports[] array, which has a
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size of 256. The IN instruction will use the appropriate element of
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this array. This array is initialised to all zeroes.
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The output port values can be queried from the z80_outports[] array,
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which has also a size of 256. The OUT instruction will store the value
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in the element addressed by the instruction.
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If you need more complex behaviour of the I/O, you must redefine the
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appropriate macros in i386step.S and z80_def.h.
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Processor state
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---------------
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You can access the processor's state with the following variables and
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macros defined in "z80.h".
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Registers:
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Double registers:
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normal: BC, DE, HL, AF, IR, IX, IY, PC, SP,
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aux: BCBK, DEBK, HLBK, AFBK
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Single registers:
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RB, RC, RD, RE, RH, RL, RA, RF, RI, RR, XH, XL, YH, YL, PCH, PCL, SPH, SPL
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Misc state:
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z80_proc.haltstate (1: processor is in halt mode, 0: processor is runnig)
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z80_proc.it_mode (interrupt mode 0, 1 or 2)
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z80_proc.iff1 (interrupt flip-flop 1)
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z80_proc.iff2 (interrupt flip-flop 2)
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You need not access the other parts of z80_proc, they are meaningless
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outside the z80_step() function.
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