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41 lines
908 B
ArmAsm
41 lines
908 B
ArmAsm
;
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; 2020-01-06, Greg King
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;
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; /* Video mode defines */
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; #define VIDEOMODE_40x30 0x00
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; #define VIDEOMODE_80x60 0x02
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; #define VIDEOMODE_320x200 0x80
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; #define VIDEOMODE_SWAP (-1)
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;
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; signed char __fastcall__ videomode (signed char Mode);
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; /* Set the video mode, return the old mode.
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; ** Return -1 if Mode isn't valid.
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; ** Call with one of the VIDEOMODE_xx constants.
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; */
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;
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.export _videomode
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.import SCREEN_SET_MODE
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.include "cx16.inc"
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.proc _videomode
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ldx SCREEN_MODE ; Get old mode
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phx
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jsr SCREEN_SET_MODE
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pla ; Get back old mode
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ldx #>$0000 ; Clear high byte
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bcs @L1
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rts
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; The new mode is invalid. Go back to the old one. Return -1.
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@L1: sta SCREEN_MODE
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dex
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txa
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rts
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.endproc
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