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