WikiTI - User contributions [en]

83:ROMCalls:400C

2005-04-13T21:22:27Z

208.181.90.67: Capitalized registers

[[Category:83:ROMCalls:By_Name:Utility|DivHLByA]][[Category:83:ROMCalls:By_Name|DivHLByA]][[Category:83:ROMCalls:By_Address|400C - DivHLByA]]
== Synopsis ==
'''Official Name:''' DivHLByA

'''Call Address:''' 400C

Divides HL by A.

=== Inputs ===
* HL = dividend
* A = devisor

=== Outputs ===
* HL = quotient
* A = remainder
* BC, DE preserved
* F destroyed

== Comments ==
See also [[83:ROMCalls:4008|DivHLBy10]].

83:ROMCalls:4008

2005-04-13T21:21:28Z

208.181.90.67: Capitalized registers, added obelus

[[Category:83:ROMCalls:By_Name:Utility|DivHLBy10]][[Category:83:ROMCalls:By_Name|DivHLBy10]][[Category:83:ROMCalls:By_Address|4008 - DivHLBy10]]
== Synopsis ==
'''Official Name:''' DivHLBy10

'''Call Address:''' 4008

Divides HL by 10.

=== Inputs ===
* HL = number

=== Outputs ===
* HL = HL ÷ 10
* A = remainder
* BC, DE preserved
* F destroyed

83Plus:RAM:97A6

2005-04-08T22:16:42Z

208.181.90.67: Same thing as for "winTop"

== Synopsis ==
'''Official Name:''' winBtm

'''Memory Address:''' 97A6h

'''Length:''' 1 bytes.

This byte is used to store the bottomrow of the current window.

== Comments ==
You can use this byte in combination with [[83Plus:RAM:97A5|winTop]] to restrict certain routines in the os to only affect the lines you want.

[[Category:83Plus:RAM:By Address|97A6 - winBtm]]
[[Category:83Plus:RAM:By Name|winBtm]]

83Plus:RAM:97A5

2005-04-08T22:15:29Z

208.181.90.67: "effect" to "affect". Grammar, people!

== Synopsis ==
'''Official Name:''' winTop

'''Memory Address:''' 97A5h

'''Length:''' 1 bytes.

This byte is used to store the toprow of the current window.

== Comments ==
You can use this byte in combination with [[83Plus:RAM:97A6|winBtm]] to restrict certain routines in the os to only affect the lines you want.

[[Category:83Plus:RAM:By Address|97A5 - winTop]]
[[Category:83Plus:RAM:By Name|winTop]]

Z80 Routines:Other:DispA

2005-04-04T22:39:09Z

208.181.90.67:

[[Category:Z80 Routines:Other|itoa]]
[[Category:Z80 Routines|itoa]]
<nowiki>
; ITOA
; --------------------------------------------------------------
; Converts a signed integer value to a zero-terminated ASCII
; string representative of that value (using radix 10).
; --------------------------------------------------------------
; INPUTS:
; HL Value to convert (two's complement integer).
; DE Base address of string destination. (pointer).
; --------------------------------------------------------------
; OUTPUTS:
; None
; --------------------------------------------------------------
; REGISTERS/MEMORY DESTROYED
; AF HL
; --------------------------------------------------------------

itoa:
push de
push bc

; Detect sign of HL.
bit 7, h
jr z, _DoConvert

; HL is negative. Output '-' to string and negate HL.
ld a, '-'
ld (de), a
inc de

; Negate HL (using two's complement)
xor a
sub l
ld l, a
ld a, 0 ; Note that XOR A or SUB A would disturb CF
sbc a, h
ld h, a

; Convert HL to digit characters
_DoConvert:
ld b, 0 ; B will count character length of number
- ld a, 10
syscall DivHLByA ; HL = HL / A, A = remainder
push af
inc b
ld a, h
or l
jr nz, -

; Retrieve digits from stack
- pop af
or $30
ld (de), a
inc de
djnz -

; Terminate string with NULL
xor a
ld (de), a

pop bc
pop de
ret
</nowiki>

----
===Comments===
*This routine uses the common [[Wikipedia:Numeral_systems#Change_of_radix|positive-integer radix conversion algorithm]] of repeatedly dividing a value by the desired radix (base case: the value is zero) and saving the remainders of each division.
*As this algorithm gives the digits in reverse order, they are pushed onto the hardware stack so that subsequently popping them yields the correct order.
*Note that the output string will not be fixed-width.

----
===Example Usage===
<nowiki> ld hl, -1004
ld de, OP1
call itoa
ld hl, OP1
syscall PutS</nowiki>

Z80 Routines:Other:DispA

2005-04-04T22:38:45Z

208.181.90.67: /* Comments */

[[Category:Z80 Routines:Other|itoa]]
[[Category:Z80 Routines|itoa]]
<nowiki>
; ITOA
; --------------------------------------------------------------
; Converts a signed integer value to a zero-terminated ASCII
; string representative of that value (using radix 10).
; --------------------------------------------------------------
; INPUTS:
; HL Value to convert (two's complement integer).
; DE Base address of string destination. (pointer).
; --------------------------------------------------------------
; OUTPUTS:
; None
; --------------------------------------------------------------
; REGISTERS/MEMORY DESTROYED
; AF HL
; --------------------------------------------------------------

itoa:
push de
push bc

; Detect sign of HL.
bit 7, h
jr z, _DoConvert

; HL is negative. Output '-' to string and negate HL.
ld a, '-'
ld (de), a
inc de

; Negate HL (using two's complement)
xor a
sub l
ld l, a
ld a, 0 ; Note that XOR A or SUB A would disturb CF
sbc a, h
ld h, a

; Convert HL to digit characters
_DoConvert:
ld b, 0 ; B will count character length of number
- ld a, 10
call DivHLByA ; HL = HL / A, A = remainder
push af
inc b
ld a, h
or l
jr nz, -

; Retrieve digits from stack
- pop af
or $30
ld (de), a
inc de
djnz -

; Terminate string with NULL
xor a
ld (de), a

pop bc
pop de
ret
</nowiki>

----
===Comments===
*This routine uses the common [[Wikipedia:Numeral_systems#Change_of_radix|positive-integer radix conversion algorithm]] of repeatedly dividing a value by the desired radix (base case: the value is zero) and saving the remainders of each division.
*As this algorithm gives the digits in reverse order, they are pushed onto the hardware stack so that subsequently popping them yields the correct order.
*Note that the output string will not be fixed-width.

----
===Example Usage===
<nowiki> ld hl, -1004
ld de, OP1
call itoa
ld hl, OP1
syscall PutS</nowiki>