Z80 Routines:Security:CRC32 - Revision history

84plusfreak: /* Memory Usage */

2006-05-29T15:31:13Z

‎Memory Usage

84plusfreak at 09:58, 16 May 2006

2006-05-16T09:58:47Z

84plusfreak: wikified

2006-05-16T09:52:19Z

wikified

84plusfreak at 09:50, 16 May 2006

2006-05-16T09:50:11Z

New page

[[Category:Z80 Routines:Security|CRC32]][[Category:Z80 Routines|CRC32]]
I (84plusfreak) made this routine on-calc.
If you find an error, please tell me (serninpc at gmail dot com).

==CRC32Init==

CRC32Init:
;Inputs:
; A=0 -> Use 'default' Polynomial (the one used in the ZIP Format)
; A=1 -> Use custom Polynomial
; -> DEHL=Polynomial
;Outputs:
; ($8292)=Polynomial
; ($8296)=Current CRC (~($8296)=CRC32)
;Destroys:
; AF,DE,HL
or a
jr nz,$+08
ld de,$EDB8
ld hl,$8320
ld a,d
ld d,e
ld e,a
ld a,h
ld h,l
ld l,a
ld ($8292),de
ld ($8294),hl
ld hl,$FFFF
ld ($8296),hl
ld ($8298),hl
ret

==CRC32Update==

CRC32Update:
;Inputs:
; HL -> Points to data
; BC -> Number of bytes
;Outputs:
; ($8296) = Updated
;Destroys:
; AF,BC,DE,HL
ld a,b
or c
ret z
push hl
push bc
ld b,(hl)
call CRC32Update_Routine
pop bc
pop hl
inc hl
dec bc
jr CRC32Update
CRC32Update_OneByte:
;Inputs:
; A = Byte to add to CRC
;Destroys:
; AF,BC,DE,HL
ld b,a
CRC32Update_Routine:
ld a,($8296)
xor b
call CRC32TableLookup
ld a,($8297)
xor l
ld ($8296),a
ld a,($8298)
xor h
ld ($8297),a
ld a,($8299)
xor e
ld ($8298),a
ld a,d
ld ($8299),a
ret
CRC32TableLookup:
ld de,$0000
ld h,d
ld l,a
ld b,8
CRC32TableLookupLoop:
push bc
or a
rr d
rr e
rr h
rr l
jr nc,CRC32TableLookupLoopEnd
push hl
pop bc
ld hl,$8292
ld a,d
xor (hl)
inc hl
ld d,a
ld a,e
xor (hl)
inc hl
ld e,a
ld a,b
xor (hl)
inc hl
ld b,a
ld a,c
xor (hl)
ld c,a
push bc
pop hl
CRC32TableLookupLoopEnd:
pop bc
djnz CRC32TableLookupLoop
ret

==CRC32Finalize==

CRC32Finalize:
;Inputs:
; None
;Outputs:
; DEHL = CRC32
;Destroys:
; AF,BC,DE,HL
ld de,($8298)
ld bc,($8296)
ld hl,$FFFF
push hl
or a
sbc hl,bc
ex (sp),hl
sbc hl,de
ex de,hl
pop hl
ret

@@ Line 10: / Line 10: @@
 These routines use RAM that is also used by the built-in MD5 routines.
-The code takes 149 bytes in your program.
+The code takes 147 bytes in your program.
 == The code ==

@@ Line 5: / Line 5: @@
 I (84plusfreak) made this routine on-calc.
 If you find an error, please tell me (serninpc at gmail dot com).
 == The code ==

@@ Line 1: / Line 1: @@
 [[Category:Z80 Routines:Security|CRC32]][[Category:Z80 Routines|CRC32]]
 I (84plusfreak) made this routine on-calc.
 If you find an error, please tell me (serninpc at gmail dot com).
-==CRC32Init==
+== The code ==
   CRC32Init:
@@ Line 32: / Line 37: @@
    ret
-==CRC32Update==
+=== CRC32Update ===
   CRC32Update:
@@ Line 114: / Line 119: @@
    ret
-==CRC32Finalize==
+=== CRC32Finalize ===
   CRC32Finalize: