mirror of https://github.com/hsoft/collapseos.git
33 lines
702 B
NASM
33 lines
702 B
NASM
; Font management
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;
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; There can only ever be one active font.
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;
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; *** Defines ***
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; FNT_DATA: Pointer to the beginning of the binary font data to work with.
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; FNT_WIDTH: Width of the font.
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; FNT_HEIGHT: Height of the font.
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;
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; *** Code ***
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; If A is in the range 0x20-0x7e, make HL point to the beginning of the
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; corresponding glyph and set Z to indicate success.
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; If A isn't in the range, do nothing and unset Z.
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fntGet:
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cp 0x20
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ret c ; A < 0x20. Z was unset by cp
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cp 0x7f
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jp nc, unsetZ ; A >= 0x7f. Z might be set
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push af ; --> lvl 1
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push bc ; --> lvl 2
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sub 0x20
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ld hl, FNT_DATA
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ld b, FNT_HEIGHT
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.loop:
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call addHL
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djnz .loop
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pop bc ; <-- lvl 2
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pop af ; <-- lvl 1
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cp a ; set Z
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ret
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