1 /*****************************************************************************/
5 /* CPU core for the 6502 */
9 /* (C) 2003-2012, Ullrich von Bassewitz */
10 /* Roemerstrasse 52 */
11 /* D-70794 Filderstadt */
12 /* EMail: uz@cc65.org */
15 /* This software is provided 'as-is', without any expressed or implied */
16 /* warranty. In no event will the authors be held liable for any damages */
17 /* arising from the use of this software. */
19 /* Permission is granted to anyone to use this software for any purpose, */
20 /* including commercial applications, and to alter it and redistribute it */
21 /* freely, subject to the following restrictions: */
23 /* 1. The origin of this software must not be misrepresented; you must not */
24 /* claim that you wrote the original software. If you use this software */
25 /* in a product, an acknowledgment in the product documentation would be */
26 /* appreciated but is not required. */
27 /* 2. Altered source versions must be plainly marked as such, and must not */
28 /* be misrepresented as being the original software. */
29 /* 3. This notice may not be removed or altered from any source */
32 /*****************************************************************************/
41 /*****************************************************************************/
43 /*****************************************************************************/
48 typedef enum CPUType {
56 /* 6502 CPU registers */
57 typedef struct CPURegs CPURegs;
59 unsigned AC; /* Accumulator */
60 unsigned XR; /* X register */
61 unsigned YR; /* Y register */
62 unsigned ZR; /* Z register */
63 unsigned SR; /* Status register */
64 unsigned SP; /* Stackpointer */
65 unsigned PC; /* Program counter */
68 /* Status register bits */
69 #define CF 0x01 /* Carry flag */
70 #define ZF 0x02 /* Zero flag */
71 #define IF 0x04 /* Interrupt flag */
72 #define DF 0x08 /* Decimal flag */
73 #define BF 0x10 /* Break flag */
74 #define OF 0x40 /* Overflow flag */
75 #define SF 0x80 /* Sign flag */
79 /*****************************************************************************/
81 /*****************************************************************************/
86 /* Generate a CPU RESET */
88 void IRQRequest (void);
91 void NMIRequest (void);
94 unsigned ExecuteInsn (void);
95 /* Execute one CPU instruction. Return the number of clock cycles for the
96 ** executed instruction.
99 unsigned long GetCycles (void);
100 /* Return the total number of clock cycles executed */
102 extern int PrintCycles;
103 /* flag to print cycles at program termination */