Routines
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ED6D: Defines a single key
Waits for an unambiguous key press, rejects it if that key is already in use, stores it in temp_keydefs, then looks the key's two-character name up in key_names and draws it at DE. The screen address is advanced by one character row on the way out, and by two when B is 4, which is the gap in the middle of the printed list.
Used by the routine at redefine_keys_48k.
Input
B Position in the eight-key list, counting down from 8. 4 inserts the extra row gap
C Index of key to define
DE Screen address at which the key name is drawn
Output
DE Screen address of the next row
define_a_key ED6D PUSH DE Preserve DE, BC
ED6E PUSH BC
dak_loop1 ED6F CALL play_music_48k Call play_music_48k
ED72 CALL redefine_keyscan Call redefine_keyscan
ED75 JR NZ,dak_loop1 Loop while the scan was ambiguous
ED77 INC D Loop while no key at all was down ($FF)
ED78 JR Z,dak_loop1
ED7A DEC D D--
ED7B LD A,D A = D
ED7C POP BC Retrieve index in C
ED7D PUSH BC
ED7E LD HL,$EE38 Point HL at temp_keydefs
ED81 LD B,C B = C - 1
ED82 DEC B
ED83 JR Z,dak_store Jump if zero -- can't be used
Checking for existing uses of that key.
dak_check_used ED85 CP (HL)
ED86 JR Z,dak_loop1 Already used - try again
ED88 INC HL HL++
ED89 DJNZ dak_check_used Loop while B > 0
dak_store ED8B POP BC Retrieve index in C
ED8C PUSH BC
ED8D LD HL,$EE37 Point at temp_keydefs (1-indexed)
ED90 LD B,$00 BC = C to widen the index
ED92 ADD HL,BC Write byte
ED93 LD (HL),A
ED94 LD HL,$EDD6 Point at key names (two chars per key)
ED97 LD D,$00 D = 0
ED99 LD B,A B = A
ED9A AND $07 A &= 7 -- half row
ED9C LD C,A A *= 5 -- multiply half row by 5
ED9D ADD A,A
ED9E ADD A,A
ED9F ADD A,C
EDA0 SRL B B >>= 3 -- key
EDA2 SRL B
EDA4 SRL B
EDA6 ADD A,B A += B
EDA7 ADD A,A A += A
EDA8 LD E,A DE = A (D is zero)
EDA9 ADD HL,DE HL += DE
EDAA POP BC Retrieve DE and index?
EDAB POP DE
EDAC PUSH BC
EDAD PUSH DE
EDAE LD ($EADD),DE Poke screen address into key string
EDB2 LD A,(HL) A = *HL -- read a byte of key name
EDB3 LD ($EADF),A Poke first byte of key name
EDB6 INC HL HL++
EDB7 LD A,(HL) A = *HL -- read another byte of key name
EDB8 SET 7,A Terminate the second byte
EDBA LD ($EAE0),A Poke into key string
EDBD LD HL,$EADC Draw the key string
EDC0 CALL menu_draw_string
EDC3 POP DE
EDC4 CALL dak_move_down Advance to next? character row
EDC7 POP BC
EDC8 LD A,B Return if B != 4
EDC9 CP $04
EDCB RET NZ
dak_move_down EDCC LD A,E E += 32
EDCD ADD A,$20
EDCF LD E,A
EDD0 RET NC
EDD1 LD A,D D += 8
EDD2 ADD A,$08
EDD4 LD D,A
EDD5 RET Return
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