ORCA-C/CCommon.asm

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mcopy ccommon.macros
****************************************************************
*
* CopyString - copy a string
*
* Inputs:
* toPtr - location to copy to
* fromPtr - location to copy from
*
****************************************************************
*
CopyString start cc
subroutine (4:toPtr,4:fromPtr),0
short I,M
lda [fromPtr]
sta [toPtr]
tay
lb1 lda [fromPtr],Y
sta [toPtr],Y
dey
bne lb1
long I,M
return
end
****************************************************************
*
* Hash - find hash displacement
*
* Finds the displacement into an array of pointers using a
* hash function.
*
* Inputs:
* sPtr - points to string to find hash for
*
* Outputs:
* Returns the disp into the hash table
*
****************************************************************
*
Hash start cc
hashSize equ 876 # hash buckets - 1
disp equ 0 disp into hash table
length equ 2 length of string
subroutine (4:sPtr),4
lda [sPtr] set the length of the string
tax
and #$00FF
sta length
ldy #1 start with char 1
txa if 1st char is '~', start with char 6
and #$FF00
cmp #'~'*256
bne lb0
ldy #6
lb0 lda #0 initial value is 0
bra lb2 while there are at least 2 chars left
lb1 asl a rotate sum left one bit
adc [sPtr],Y add in next two bytes
iny advance two chars
iny
lb2 cpy length
blt lb1
bne lb3 if there is 1 char left then
asl a rotate sum left one bit
sta disp
lda [sPtr],Y
and #$00FF and out the high byte
adc disp add last byte to the sum
sec
lb3 sbc #hashSize+1 disp := (sum mod (hashSize+1)) << 2
bcs lb3
adc #hashSize+1
asl a
asl a
sta disp
return 2:disp return disp
end