Some PIA register #defines

Some register #defines for PIA.

(Some may be too Atari-centric -- I know PIA chip was used by PET &
perhaps other platforms supported by cc65.  If so, perhaps we can
define them elsewhere.  Not sure whether they'd be the same for 5200;
I admit I know zilch about that system except that it's _more or less_
an Atari 400)

diff --git a/include/_pia.h b/include/_pia.h
index 867c8f8a51cdb52b8cda0c4e224e74fcc365e665..bd4f7c8baf665364bf5ae800cfa3ef7e48958251 100644 (file)
--- a/include/_pia.h
+++ b/include/_pia.h
@@ -4,9 +4,14 @@
 /*                                                                           */
 /*                Internal include file, do not use directly                 */
 /*                                                                           */
+/* The Peripheral Interface Adapter (PIA) chip provides parallel I/O         */
+/* interfacing; it was used in Atari 400/800 and Commodore PET family of     */
+/* computers, for joystick and interrupts.                                   */
+/* - Sources; various + Wikpedia article on "Peripheral Interface Adapter"   */
 /*                                                                           */
 /*                                                                           */
 /* (C) 2000 Freddy Offenga <taf_offenga@yahoo.com>                           */
+/* 2019-01-13: Bill Kendrick <nbs@sonic.net>: Defines for registers          */
 /*                                                                           */
 /*                                                                           */
 /* This software is provided 'as-is', without any expressed or implied       */
@@ -34,18 +39,45 @@
 #define __PIA_H
 
 
-/* Define a structure with the pia register offsets */
+/* Define a structure with the PIA register offsets */
 struct __pia {
     unsigned char   porta;  /* port A data r/w */
+/* Paddle 0-3 triggers (per PORTA bits) */
+#define PORTA_PTRIG3 0x80
+#define PORTA_PTRIG2 0x40
+#define PORTA_PTRIG1 0x08
+#define PORTA_PTRIG0 0x04
+
+
     unsigned char   portb;  /* port B data r/w */
+/* Paddle 4-7 triggers (per PORTB bits); only 400/800 had four controller ports */
+#define PORTB_PTRIG7 0x80
+#define PORTB_PTRIG6 0x40
+#define PORTB_PTRIG5 0x08
+#define PORTB_PTRIG4 0x04
+
+    /* See also: "JOY_xxx_MASK" in "atari.h" */
+
     unsigned char   pactl;  /* port A control */
     unsigned char   pbctl;  /* port B control */
+
+#define PxCTL_IRQ_ENABLE    0x01 /* (W) Peripheral A interrupt (IRQ) enable. */
+  /* One equals enable. Set by the OS but available to the user;
+     reset on powerup. */
+#define PxCTL_BIT1          0x02 /* "Set to zero" */
+#define PxCTL_ADDRESSING    0x04 /* (W) Controls PORTA addressing */
+  /* One equals PORTA register; zero equals direction control register */
+#define PACTL_MOTOR_CONTROL 0x08 /* (W) Peripheral motor control line (turn the cassette on
+                     or off; zero equals on) */
+#define PBCTL_PERIPH_CMD_IDENT 0x08 /* Peripheral command identification (serial bus command) */
+#define PxCTL_BIT4          0x10 /* "Set to one" */
+#define PxCTL_BIT5          0x20 /* "Set to one" */
+#define PxCTL_BIT6          0x40 /* "Set to zero" */
+#define PxCTL_IRQ_STATUS    0x80 /* Peripheral interrupt (IRQ) status bit. */
+  /* Set by Peripherals (PORTA / PORTB). Reset by reading PORTA / PORTB*/
 };
 
 
 
 /* End of _pia.h */
 #endif
-
-
-