KermMartian: Created page with "The main source of user input will be through the keypad, so almost every input routine will require use of a GetKey function. '''Note:''' This page will need to have routine..."

2016-02-05T06:38:36Z

Created page with "The main source of user input will be through the keypad, so almost every input routine will require use of a GetKey function. '''Note:''' This page will need to have routine..."

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The main source of user input will be through the keypad, so almost every input routine will require use of a GetKey function.

'''Note:''' This page will need to have routines for actual user input aside from GetKey routines.

= GetKey =
This is essentially like several of the OS routines. If OS interrupts are read, you can also read from address 8445h. But if you really want a custom routine:

;===============================================================
GetKey:
;===============================================================
;Outputs:
; A is a value from 0 to 56 that is the keypress
; HL is not modified
; BC is not modified
;Destroys:
; D
; E is destroyed if no keys are pressed, else it is also the keypress
;===============================================================
ld de,$7FFF
KeyLoop:
rlc d
ld a,d
out (1),a
sub 7Fh
ret z
ld a,e
add a,8
ld e,a
in a,(1)
inc a
jr z,KeyLoop
dec a
inc e
rra
jr c,$-2
ld a,e
ret

= ScanAllKeys =
This routine requires 7 bytes of RAM pointed to by HL. This will return the value of all the key groups, stored in each of the bytes:

ScanAllKeys:
;Inputs:
; HL points to the 7 bytes to output the result to
;Notes:
; There is not enough delay for 15MHz
ld bc,0701h
ld a,$FE ;test the keys
KeyUpdateLoop:
out (1),a
rlca
nop
ini
jr nz,KeyUpdateLoop
ret

{{lowercase}}
[[Category:Z80 Assembly]]
[[Category:Z80 Heaven]]

Z80:Input Routines - Revision history

KermMartian: Created page with "The main source of user input will be through the keypad, so almost every input routine will require use of a GetKey function. '''Note:''' This page will need to have routine..."