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b04d79b1da
This PR is mostly a complete rewrite of the emulator for 6502/65c02 opcodes. It provides an easier to maintain implementation of the instructions, by using few macros rather than having hand-written code for each function. All undocumented, previously missing opcodes for 6502 are also implemented. The patch also includes a detailed documentation of those opcodes, for reference to developers. This PR should fix one of the milestones listed here for the next version of CC65: https://github.com/cc65/wiki/wiki/Before-the-next-release
104 lines
4.2 KiB
C
104 lines
4.2 KiB
C
/*****************************************************************************/
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/* */
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/* 6502.h */
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/* */
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/* CPU core for the 6502 */
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/* */
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/* */
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/* */
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/* (C) 2003-2012, Ullrich von Bassewitz */
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/* Roemerstrasse 52 */
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/* D-70794 Filderstadt */
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/* EMail: uz@cc65.org */
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/* */
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/* */
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/* This software is provided 'as-is', without any expressed or implied */
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/* warranty. In no event will the authors be held liable for any damages */
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/* arising from the use of this software. */
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/* */
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/* Permission is granted to anyone to use this software for any purpose, */
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/* including commercial applications, and to alter it and redistribute it */
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/* freely, subject to the following restrictions: */
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/* */
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/* 1. The origin of this software must not be misrepresented; you must not */
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/* claim that you wrote the original software. If you use this software */
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/* in a product, an acknowledgment in the product documentation would be */
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/* appreciated but is not required. */
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/* 2. Altered source versions must be plainly marked as such, and must not */
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/* be misrepresented as being the original software. */
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/* 3. This notice may not be removed or altered from any source */
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/* distribution. */
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/* */
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/*****************************************************************************/
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#ifndef _6502_H
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#define _6502_H
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/*****************************************************************************/
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/* Data */
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/*****************************************************************************/
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/* Supported CPUs */
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typedef enum CPUType {
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CPU_6502,
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CPU_65C02,
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CPU_6502X
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} CPUType;
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/* Current CPU */
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extern CPUType CPU;
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/* 6502 CPU registers */
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typedef struct CPURegs CPURegs;
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struct CPURegs {
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unsigned AC; /* Accumulator */
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unsigned XR; /* X register */
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unsigned YR; /* Y register */
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unsigned ZR; /* Z register */
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unsigned SR; /* Status register */
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unsigned SP; /* Stackpointer */
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unsigned PC; /* Program counter */
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};
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/* Status register bits */
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#define CF 0x01 /* Carry flag */
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#define ZF 0x02 /* Zero flag */
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#define IF 0x04 /* Interrupt flag */
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#define DF 0x08 /* Decimal flag */
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#define BF 0x10 /* Break flag */
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#define OF 0x40 /* Overflow flag */
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#define SF 0x80 /* Sign flag */
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/*****************************************************************************/
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/* Code */
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/*****************************************************************************/
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void Reset (void);
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/* Generate a CPU RESET */
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void IRQRequest (void);
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/* Generate an IRQ */
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void NMIRequest (void);
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/* Generate an NMI */
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unsigned ExecuteInsn (void);
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/* Execute one CPU instruction. Return the number of clock cycles for the
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** executed instruction.
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*/
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/* End of 6502.h */
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#endif
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