#ifndef _MC6821_H_
#define _MC6821_H_

/*
* This file describes the memery mapping of the MC6821 PIA.
* The unions describe overlayed registers. Which of them is used is
* determined by bit 2 of the corresponding control register.
* this files expects the PIA_REG_PADWIDTH to be defined the numeric
* value of the register spacing.
*
* Data came from MFC-31-Developer Kit (from Ralph Seidel,
* [email protected]) and Motorola Data Sheet (from
* Richard Hirst, [email protected])
*
* 6.11.95 copyright Joerg Dorchain ([email protected])
*
*/

#ifndef PIA_REG_PADWIDTH
#define PIA_REG_PADWIDTH 255
#endif

struct pia {
union {
volatile u_char pra;
volatile u_char ddra;
} ua;
u_char pad1[PIA_REG_PADWIDTH];
volatile u_char cra;
u_char pad2[PIA_REG_PADWIDTH];
union {
volatile u_char prb;
volatile u_char ddrb;
} ub;
u_char pad3[PIA_REG_PADWIDTH];
volatile u_char crb;
u_char pad4[PIA_REG_PADWIDTH];
};

#define ppra ua.pra
#define pddra ua.ddra
#define pprb ub.prb
#define pddrb ub.ddrb

#define PIA_C1_ENABLE_IRQ (1<<0)
#define PIA_C1_LOW_TO_HIGH (1<<1)
#define PIA_DDR (1<<2)
#define PIA_IRQ2 (1<<6)
#define PIA_IRQ1 (1<<7)

#endif