58 lines
1.4 KiB
Plaintext
58 lines
1.4 KiB
Plaintext
// petulant.60p - The PETulant Cursor, a "display hack" for the Commodore 64
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// Originally written by Chris Pressey sometime in the late 1980's
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// Rewritten in P65 assembly and released March 2008
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// Rewritten in SixtyPical in March 2018
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// SPDX-FileCopyrightText: Chris Pressey, the author of this work, has dedicated it to the public domain.
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// For more information, please refer to <https://unlicense.org/>
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// SPDX-License-Identifier: Unlicense
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// ----- Types -----
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typedef routine
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inputs border, blnon, color, background
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outputs border
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trashes a, z, n
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irq_handler
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// ----- Addresses -----
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vector irq_handler cinv @ $314 // hw irq interrupt, 60x per second
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byte blnon @ $cf // was last cursor blink on or off?
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byte color @ $286 // current foreground colour for text
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byte border @ $d020 // colour of border of the screen
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byte background @ $d021 // colour of background of the screen
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// ----- Variables -----
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vector irq_handler save_cinv
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// ----- Interrupt Handler -----
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define our_cinv irq_handler
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{
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ld a, blnon
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if not z {
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ld a, color
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} else {
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ld a, background
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}
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st a, border
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goto save_cinv
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}
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// ----- Main Program -----
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define main routine
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inputs cinv
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outputs cinv, save_cinv
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trashes a, n, z
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{
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with interrupts off {
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copy cinv, save_cinv
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copy our_cinv, cinv
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}
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}
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