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They simplify C programs' direct access to VERA's internal address space.
20 lines
465 B
ArmAsm
20 lines
465 B
ArmAsm
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; 2019-10-22, Greg King
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; unsigned char fastcall vpeek (unsigned long addr);
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; /* Get a byte from a location in VERA's internal address space. */
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;
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.export _vpeek
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.import vset
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.include "cx16.inc"
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_vpeek: php ; (vset blocks interrupts)
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jsr vset ; put VERA's address
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ldx #>$0000
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lda VERA::DATA0 ; read VERA port zero
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plp
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rts
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