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49 lines
2.1 KiB
Plaintext
49 lines
2.1 KiB
Plaintext
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Joystick Functions for C02 Programs
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This module contains constants and a function for reading digital joysticks
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(the type used on Atari and Commodore 8-bit computers). For systems that use
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analog joysticks (such as the Apple II), the paddle module should be used.
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The constants and assembly code vary by system, so when invoking the
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cross-compilers, the command line option -s must be used to ensure that
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the correct header files are included.
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At the beginning of the program use the directives
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#include <joystk.h02>
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The following constants are defined:
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#JYSTKS Maximum number of joysticks supported by system.
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For systems with no joystick support, this will be 0.
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#JOYUP Joystick Switch Bitmask - Up
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#JOYDN Joystick Switch Bitmask - Down
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#JOYLF Joystick Switch Bitmask - Left
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#JOYRT Joystick Switch Bitmask - Right
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#JOYB0 Joystick Switch Bitmask - Fire Button
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The following functions are defined:
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j = joystk(n); Returns the current state of joystick n.
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If n is greater than or equal to #JYSTKS then $FF
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will be returned. Otherwise, a byte representing the
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state of the joystick switches will be returned.
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Each switch in the joystick has a corresponding bit
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in the result which will be 1 if the switch is
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depressed or 0 if it is not.
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The specific assignment of bits varies by system, so
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the joystick bitmask constants should be used to check
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the state of the individual switches.
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The state of an individual switch can be determined by
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doing a bitwise and of the result with the corresponding
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bitmask constant, which will result in a non-zero value
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if and only if that switch is depressed.
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Note: This library has no external dependencies.
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