/* */
/* (C) 2000 Freddy Offenga <taf_offenga@yahoo.com> */
/* 24-Jan-2011: Christian Krueger: Added defines for Antic instruction set */
-/* 2019-01-12: Bill Kendrick <nbs@sonic.net>: More defines for registers */
+/* 2019-01-14: Bill Kendrick <nbs@sonic.net>: More defines for registers */
/* */
/* */
/* This software is provided 'as-is', without any expressed or implied */
/* Define a structure with the ANTIC coprocessor's register offsets */
struct __antic {
unsigned char dmactl; /* (W) direct memory access control */
+ unsigned char chactl; /* (W) character mode control */
+ unsigned char dlistl; /* display list pointer low-byte */
+ unsigned char dlisth; /* display list pointer high-byte */
+ unsigned char hscrol; /* (W) horizontal scroll enable */
+ unsigned char vscrol; /* (W) vertical scroll enable */
+ unsigned char unuse0; /* unused */
+ unsigned char pmbase; /* (W) msb of p/m base address (for when DMACTL has player and/or missile DMA enabled) */
+ unsigned char unuse1; /* unused */
+ unsigned char chbase; /* (W) msb of character set base address */
+ unsigned char wsync; /* (W) wait for horizontal synchronization */
+ unsigned char vcount; /* (R) vertical line counter */
+ unsigned char penh; /* (R) light pen horizontal position */
+ unsigned char penv; /* (R) light pen vertical position */
+ unsigned char nmien; /* (W) non-maskable interrupt enable */
+ unsigned char nmires;
+ /* (W) ("NMIRES") nmi reset -- clears the interrupt request register; resets all of the NMI status together
+ ** (R) ("NMIST") nmi status -- holds cause for the NMI interrupt
+ */
+};
+
+
+/* DMACTL register options */
+/* Initialized to 0x22: DMA fetch, normal playfield, no PMG DMA, double-line PMGs */
/* Playfield modes: */
#define DMACTL_PLAYFIELD_NONE 0x00
#define DMACTL_PLAYFIELD_NARROW 0x01 /* e.g., 32 bytes per scanline with thick borders */
#define DMACTL_PLAYFIELD_NORMAL 0x02 /* e.g., 40 bytes per scanline with normal borders */
#define DMACTL_PLAYFIELD_WIDE 0x03 /* e.g., 48 bytes per scanline with no borders (overscan) */
+
/* Other options: */
-#define DMACTL_DMA_MISSILES 0x04 /* if not set, GTIA's GRAFP0 thru GRAFP3 used for player shapes; if set, ANTIC's PMBASE will be used to fetch shapes via DMA */
-#define DMACTL_DMA_PLAYERS 0x08 /* (ditto, using GTIA's GRAFM for missile shapes...) */
-#define DMACTL_PMG_SINGLELINE 0x10 /* if not set, default is double-scanline resolution PMGs */
-#define DMACTL_DMA_FETCH 0x20 /* if not set, disables ANTIC operation since it cannot fetch Display List instructions */
-/* Initialized to 0x22 (DMA fetch, normal playfield, no PMG DMA, double-line PMGs) */
+/* If not set, GTIA's GRAFP0 thru GRAFP3, and/or GRAFM registers are used for
+** player & missile shapes, respectively. (Modify the registers during the horizontal blank
+** (Display List Interrupt), a la "racing the beam" on an Atari VCS/2600, )
+** if set, ANTIC's PMBASE will be used to fetch shapes from memory via DMA.
+*/
+#define DMACTL_DMA_MISSILES 0x04
+#define DMACTL_DMA_PLAYERS 0x08
- unsigned char chactl; /* (W) character mode control */
+/* Unless set, PMGs (as fetched via DMA) will be double-scanline resolution */
+#define DMACTL_PMG_SINGLELINE 0x10
+
+/* Unless set, ANTIC operation is disabled, since it cannot fetch
+** Display List instructions
+*/
+#define DMACTL_DMA_FETCH 0x20
+
+
+/* CHACTL register options */
+/* Initialized to 2 (CHACTL_CHAR_NORMAL | CHACTL_INV_PRESENT) */
/* Inverted (upside-down) characters */
#define CHACTL_CHAR_NORMAL 0x00
#define CHACTL_INV_OPAQUE 0x01 /* chars with high-bit appear as space */
#define CHACTL_INV_PRESENT 0x02 /* chars with high-bit are reverse-video */
-/* N.B. Default is "CHACTL_CHAR_NORMAL | CHACTL_INV_PRESENT", aka decimal 2 */
+/* Register bits for NMIEN (enabling interrupts)
+** and NMIST (determining the cause for the NMI interrupt)
+*/
- unsigned char dlistl; /* display list pointer low-byte */
- unsigned char dlisth; /* display list pointer high-byte */
- unsigned char hscrol; /* (W) horizontal scroll enable */
- unsigned char vscrol; /* (W) vertical scroll enable */
- unsigned char unuse0; /* unused */
- unsigned char pmbase; /* (W) msb of p/m base address (for when DMACTL has player and/or missile DMA enabled) */
- unsigned char unuse1; /* unused */
- unsigned char chbase; /* (W) character set base address */
- unsigned char wsync; /* (W) wait for horizontal synchronization */
- unsigned char vcount; /* (R) vertical line counter */
- unsigned char penh; /* (R) light pen horizontal position */
- unsigned char penv; /* (R) light pen vertical position */
+#define NMIEN_DLI 0x80
+/* Display List Interrupts
+** Called on a modeline when "DL_DLI" bit is set the ANTIC instruction,
+** and jumps through VDSLST vector.
+*/
- unsigned char nmien; /* (W) non-maskable interrupt enable */
+#define NMIEN_VBI 0x40
+/* Vertical Blank Interrupt
+** Called during every vertical blank; see SYSVBV, VVBLKI, CRITIC, and VVBLKD,
+** as well as the SETVBV routine.
+*/
-/* NMIEN settings: */
-#define NMIEN_DLI 0x80 /* see also: DL_DLI */
-#define NMIEN_VBI 0x40
#define NMIEN_RESET 0x20
-
- unsigned char nmires; /* (W) ("NMIRES") nmi reset; (R) ("NMIST") nmi status */
-};
+/* [Reset] key pressed */
/* ANTIC instruction set */
projects / cc65 / blobdiff