51 lines
1.0 KiB
NASM
51 lines
1.0 KiB
NASM
; Keyboard driver
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; @author Daniele Verducci
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;
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; Requires declaration of following pointers, one for every column of the keys grid:
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; KEYB_A0_REG
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; KEYB_A1_REG
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; KEYB_A2_REG
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; KEYB_A3_REG
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; KEYB_A4_REG
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; These address must be exclusive if a decoder is not present.
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;
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; Example (no decoder):
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; KEYB_A0_REG = 0000001
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; KEYB_A1_REG = 0000010
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; KEYB_A2_REG = 0000100
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; KEYB_A3_REG = 0001000
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; etc...
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;
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; Example (with decoder):
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; KEYB_A0_REG = 0000000
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; KEYB_A1_REG = 0000001
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; KEYB_A2_REG = 0000010
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; KEYB_A3_REG = 0000011
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; etc...
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; Reads the keyboard
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; @return: a 0-terminated array of keycodes representing the pressed keys
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Keyb_read:
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in a, (KEYB_A0_REG)
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cp 0
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jp z, _keyb_read_a1
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add a, %01000000
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call Lcd_printc ; A already contains char to print
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_loop:
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in a, (KEYB_A0_REG)
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cp 0
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jp nz, _loop
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ret
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_keyb_read_a1:
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in a, (KEYB_A1_REG)
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cp 0
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ret z
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add a, %01010000
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call Lcd_printc ; A already contains char to print
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_loop2:
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in a, (KEYB_A1_REG)
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cp 0
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jp nz, _loop2
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ret
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