vcslib.h

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// Copyright 2023 LLVM-MOS Project
// Licensed under the Apache License, Version 2.0 with LLVM Exceptions.
// See https://github.com/llvm-mos/llvm-mos-sdk/blob/main/LICENSE for license
// information.
 
#ifndef _VCSLIB_H
#define _VCSLIB_H
 
#include <atari2600.h>
#include <stdint.h>
 
#if defined(__ATARI2600_MAPPER__)
#include <mapper.h>
#endif
 
// Define data types for different data sizes and signedness
 
typedef unsigned char byte;   // 8-bit unsigned data type
typedef signed char sbyte;    // 8-bit signed data type
typedef unsigned short word;  // 16-bit unsigned data type
 
// Atari 2600 kernel helpers, called in a sequence every frame
 
void kernel_1(void);    // before preframe
void kernel_2(void);    // before kernel
void kernel_3(void);    // after kernel
void kernel_4(void);    // after postframe
 
// Function to set horizontal position of a game object.
 
typedef enum { PLAYER_0=0, PLAYER_1, MISSILE_0, MISSILE_1, BALL } TIAObject;
 
// A = X coordinate
// X = object index
__attribute__((leaf)) void _set_horiz_pos(byte xpos, byte objindex);
 
// swap order of call
#define set_horiz_pos(objindex,xpos) _set_horiz_pos(xpos,objindex)
 
// Waits for next scanline start
#define do_wsync() \
__attribute__((leaf)) asm volatile("sta $42 /* WSYNC */");
 
// Applies horizontal motion to sprite(s) after set_horiz_pos()
#define apply_hmove() \
__attribute__((leaf)) asm volatile("sta $42 /* WSYNC */" "\n" "sta $6a /* HMOVE */");
 
// Macros
 
#define P0  0
#define P1  1
#define M0  2
#define M1  3
#define BALL    4
 
#define SW_RESET()  ((RIOT.swchb & RESET_MASK) == 0)
#define SW_SELECT() ((RIOT.swchb & SELECT_MASK) == 0)
#define SW_COLOR()  ((RIOT.swchb & BW_MASK) != 0)
#define SW_P0_PRO() ((RIOT.swchb & P0_DIFF_MASK) != 0)
#define SW_P1_PRO() ((RIOT.swchb & P1_DIFF_MASK) != 0)
 
#define JOY_UP(plyr)    (!(RIOT.swcha & ((plyr) ? 0x1 : ~MOVE_UP)))
#define JOY_DOWN(plyr)  (!(RIOT.swcha & ((plyr) ? 0x2 : ~MOVE_DOWN)))
#define JOY_LEFT(plyr)  (!(RIOT.swcha & ((plyr) ? 0x4 : ~MOVE_LEFT)))
#define JOY_RIGHT(plyr) (!(RIOT.swcha & ((plyr) ? 0x8 : ~MOVE_RIGHT)))
#define JOY_FIRE(plyr)  !(((plyr) ? TIA.inpt5 : TIA.inpt4) & 0x80)
 
// make color greyscale if black and white switch is set
#define COLOR_CONV(color) (SW_COLOR() ? color : color & 0x0f)
 
// macros for setting PIA timers
#define _CYCLES(lines) (((lines) * 76) - 13)
#define _TIM64(cycles) (((cycles) >> 6) - (((cycles) & 63) < 12))
#define _T1024(cycles) ((cycles) >> 10)
 
#ifdef PAL
#define VBLANK_TIM64 _TIM64(_CYCLES(45))
#define KERNAL_T1024 _T1024(_CYCLES(250))
#define OVERSCAN_TIM64 _TIM64(_CYCLES(36))
#else
#define VBLANK_TIM64 _TIM64(_CYCLES(37))
#define KERNAL_TIM64 _TIM64(_CYCLES(194))
#define OVERSCAN_TIM64 _TIM64(_CYCLES(32))
#endif
 
#endif