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89 lines
2.2 KiB
C
89 lines
2.2 KiB
C
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/*
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* 6502.h
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*
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* Ullrich von Bassewitz, 20.09.1998
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*/
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#ifndef _6502_H
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#define _6502_H
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/* Possible returns of getcpu() */
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#define CPU_6502 0
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#define CPU_65C02 1
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#define CPU_65816 2
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unsigned char getcpu (void);
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/* Detect the CPU the program is running on */
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/* Macros for CPU instructions */
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#define BRK() __asm__ ("\tbrk")
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#define CLI() __asm__ ("\tcli")
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#define SEI() __asm__ ("\tsei")
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#define JAM() __asm__ ("\t.byte\t$02")
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/* Struct that holds the registers for the sys function */
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struct regs {
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unsigned char a; /* A register value */
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unsigned char x; /* X register value */
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unsigned char y; /* Y register value */
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unsigned char flags; /* Flags value */
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unsigned pc; /* Program counter */
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};
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/* Defines for the flags in the regs structure */
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#define F_NEG 0x80 /* N flag */
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#define F_OVF 0x40 /* V flag */
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#define F_BRK 0x10 /* B flag */
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#define F_DEC 0x08 /* D flag */
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#define F_IEN 0x04 /* I flag */
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#define F_ZERO 0x02 /* Z flag */
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#define F_CARRY 0x01 /* C flag */
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/* Function to call any machine language subroutine. All registers in the
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* regs structure are passed into the routine and the results are passed
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* out. Some of the flags are ignored on input. The called routine must
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* end with an RTS.
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*/
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void __fastcall__ _sys (struct regs* r);
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/* Set and reset the break vector. The given user function is called if
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* a break occurs. The values of the registers may be read from the brk_...
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* variables. The value in brk_pc will point to the address that contains
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* the brk instruction.
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* The set_brk function will install an exit handler that will reset the
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* vector if the program ends.
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*/
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extern unsigned char brk_a; /* A register value */
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extern unsigned char brk_x; /* X register value */
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extern unsigned char brk_y; /* Y register value */
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extern unsigned char brk_sr; /* Status register */
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extern unsigned brk_pc; /* PC value */
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typedef void (*brk_handler) (void);
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/* Type of the break handler */
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void __fastcall__ set_brk (brk_handler f);
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/* Set the break vector to the given address, return the old address */
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void reset_brk (void);
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/* Reset the break vector to the original value */
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/* End of 6502.h */
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#endif
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