...
None.
Notes
GN_Crc was implemented in OZ V4.5. It is used by the integrated EazyLink popdown to validate uploaded file content. FlashStore also uses it to display the checksum of a File Entry to be fetched to RAM. GN_Crc will be used more in future OZ developments.
If this system call is used in stand-alone applications, it is necessary to validate which OZ version the application is running on:
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include "fileio.def"
ld a,FA_PTR
ld ix,ffffh
ld de,0 ; result in DEBC
oz OS_Frm
ld a,44h ; OZ versions are embedded as hexnibbles in C register.
cp c
jr nc, not_ozv45 ; Check for OZ V4.5 failed (44h-45h gives Fc = 1) |
| Code Block |
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| title | Example for CRC - 32 on memory contents |
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include "crc32.def"
ld a,CRC_MEMA
ld hl,crctext
ld bc,crctext_end - crctext
ld de,0
oz GN_Crc
; CRC–32 returned is 0x414FA339 (DE = 0x414F, BC = 0xA339)
.crctext
defm "The quick brown fox jumps over the lazy dog"
.crctext_end |
| Code Block |
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| title | Example for CRC - 32 on open RAM file |
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include "crc32.def"
include "fileio.def"
DEFC FileBufferSize = 1280
DEFVARS $2000 ; "popdown" workspace from 2000H onwards
FileBuffer ds.b FileBufferSize ; buffer for file I/O
ENDDEF
LD A, OP_IN
LD BC,128
LD HL,filename ; pointer to local filename
LD D,H
LD E,L
OZ GN_Opf
JR C,not_available
; example with no buffer:
ld a, CRC_FILE
ld hl,0
ld de,0 ; Use FFFFFFFFh as initial Crc-32
oz GN_Crc ; get CRC-32 of Open file (no buffer)
oz GN_Cl ; close file
; example with buffer
ld a, CRC_FILE
ld hl,FileBuffer ; use buffer
ld bc,FileBufferSize
ld de,0 ; Use FFFFFFFFh as initial Crc-32
oz GN_Crc ; get CRC-32 of Open file (with buffer)
oz GN_Cl ; close file
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| Code Block |
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| title | Example for CRC - 32 on File Entry in File Card |
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include "crc32.def"
include "eprom.def"
ld c,2
ld de,epfilename ; search for filename in filea area of slot 2
ld a, EP_Find
oz OS_Epr
ret c ; file area not there
ret nz ; file entry not found
ld a, CRC_EPFL
ld de,0 ; Use FFFFFFFFh as initial Crc-32
oz GN_Crc ; get CRC-32 of File Entry
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