Shamusworld >> Repos - stargem2/blob - src/v6821.h

   1 //
   2 // Virtual 6821 (PIA) Header file
   3 //
   4 // by James Hammons
   5 //
   6 // (C) 2022 Underground Software
   7 //
   8 #ifndef __V6821_H__
   9 #define __V6821_H__
  10
  11 #include <cstddef>
  12 #include <stdint.h>
  13
  14 struct V6821PIA
  15 {
  16         public:
  17                 uint8_t ddra, ddrb;             // Data Direction Register A/B
  18                 uint8_t pa, pb;                 // Peripheral Interface A/B
  19                 uint8_t cra, crb;               // Control Register A/B
  20                 uint8_t ora, orb;               // Output Register A/B
  21                 bool ca1, ca2, cb1, cb2;        // CA1/2, CB1/2
  22                 bool irqa1, irqa2, irqb1, irqb2;        // Internal state flags
  23                 bool irqaState, irqbState;      // More internal state flags
  24
  25                 void (* IRQA)(bool);    // Address of IRQ A routine
  26                 void (* IRQB)(bool);    // Address of IRQ B routine
  27
  28
  29                 V6821PIA();                             // We have to do this because function pointers
  30                                                                 // can't have default parameters...  :-P
  31                 V6821PIA(void (* a)(bool), void (* b)(bool));
  32                 void Reset(void);
  33                 uint8_t Read(uint8_t);
  34                 void Write(uint8_t, uint8_t);
  35                 void CA1(bool);
  36                 void CA2(bool);
  37                 void CB1(bool);
  38                 void CB2(bool);
  39
  40         private:
  41                 void HandleIRQs(void);
  42 };
  43
  44 #endif  // __V6821_H__