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James Gregory 2013-12-31 11:38:48 +11:00
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@ -12,110 +12,112 @@ pages: 313-316
**Listing 16.6 OPT2.ASM**
;
; Opt2 Final optimization word count
; Written by Michael Abrash
; Modified by Willem Clements
; C/ Moncayo 5, Laurel de la Reina
; 18140 La Zubia
; Granada, Spain
; Tel 34-58-890398
; Fax 34-58-224102
;
parms struc
dw 2 dup(?)
buffer dw ?
bufferlength dw ?
charflag dw ?
wordcount dw ?
parms ends
.model small
.data
charstatustable label byte
rept 2
db 39 dup(0)
db 1
db 8 dup(0)
db 10 dup(1)
db 7 dup(0)
db 26 dup(1)
db 6 dup(0)
db 26 dup(1)
db 5 dup(0)
endm
.code
public _ScanBuffer
_ScanBuffer proc near
push bp
mov bp,sp
push si
push di
mov si,[bp+buffer]
mov bx,[bp+charflag]
mov al,[bx]
mov cx,[bp+bufferlength]
mov bx,offset charstatustable
xor di,di ; set wordcount to zero
shr cx,1 ; change count to wordcount
jc oddentry ; odd number of bytes to process
cmp al,01h ; check if last one is char
jne scanloop4 ; if not so, search for char
jmp scanloop1 ; if so, search for zero
oddentry: xchg al,ah ; last one in ah
lodsb ; get first byte
inc cx
cmp ah,01h ; check if last one was char
jne scanloop5 ; if not so, search for char
jmp scanloop2 ; if so, search for zero
;
; locate the end of a word
scanloop1: lodsw ; get two chars
xlat ; translate first
xchg al,ah ; first in ah
scanloop2: xlat ; translate second
dec cx ; count down
jz done1 ; no more bytes left
cmp ax,0101h ; check if two chars
je scanloop1 ; go for next two bytes
inc di ; increase wordcount
cmp al,01h ; check if new word started
je scanloop1 ; locate end of word
;
; locate the begin of a word
scanloop4: lodsw ; get two chars
xlat ; translate first
xchg al,ah ; first in ah
scanloop5: xlat ; translate second
dec cx ; count down
jz done2 ; no more bytes left
cmp ax,0 ; check if word started
je scanloop4 ; if not, locate begin
cmp al,01h ; check one-letter word
je scanloop1 ; if not, locate end of word
inc di ; increase wordcount
jmp scanloop4 ; locate begin of next word
done1: cmp ax,0101h ; check if end-of-word
je done ; if not, we have finished
inc di ; increase wordcount
jmp done
done2: cmp ax,0100h ; check for one-letter word
jne done ; if not, we have finished
inc di ; increase wordcount
done: mov si,[bp+charflag]
mov [si],al
mov bx,[bp+wordcount]
mov ax,[bx]
mov dx,[bx+2]
add di,ax
adc dx,0
mov [bx],di
mov [bx+2],dx
pop di
pop si
pop bp
ret
_ScanBuffer endp
end
```nasm
;
; Opt2 Final optimization word count
; Written by Michael Abrash
; Modified by Willem Clements
; C/ Moncayo 5, Laurel de la Reina
; 18140 La Zubia
; Granada, Spain
; Tel 34-58-890398
; Fax 34-58-224102
;
parms struc
dw 2 dup(?)
buffer dw ?
bufferlength dw ?
charflag dw ?
wordcount dw ?
parms ends
.model small
.data
charstatustable label byte
rept 2
db 39 dup(0)
db 1
db 8 dup(0)
db 10 dup(1)
db 7 dup(0)
db 26 dup(1)
db 6 dup(0)
db 26 dup(1)
db 5 dup(0)
endm
.code
public _ScanBuffer
_ScanBuffer proc near
push bp
mov bp,sp
push si
push di
mov si,[bp+buffer]
mov bx,[bp+charflag]
mov al,[bx]
mov cx,[bp+bufferlength]
mov bx,offset charstatustable
xor di,di ; set wordcount to zero
shr cx,1 ; change count to wordcount
jc oddentry ; odd number of bytes to process
cmp al,01h ; check if last one is char
jne scanloop4 ; if not so, search for char
jmp scanloop1 ; if so, search for zero
oddentry: xchg al,ah ; last one in ah
lodsb ; get first byte
inc cx
cmp ah,01h ; check if last one was char
jne scanloop5 ; if not so, search for char
jmp scanloop2 ; if so, search for zero
;
; locate the end of a word
scanloop1: lodsw ; get two chars
xlat ; translate first
xchg al,ah ; first in ah
scanloop2: xlat ; translate second
dec cx ; count down
jz done1 ; no more bytes left
cmp ax,0101h ; check if two chars
je scanloop1 ; go for next two bytes
inc di ; increase wordcount
cmp al,01h ; check if new word started
je scanloop1 ; locate end of word
;
; locate the begin of a word
scanloop4: lodsw ; get two chars
xlat ; translate first
xchg al,ah ; first in ah
scanloop5: xlat ; translate second
dec cx ; count down
jz done2 ; no more bytes left
cmp ax,0 ; check if word started
je scanloop4 ; if not, locate begin
cmp al,01h ; check one-letter word
je scanloop1 ; if not, locate end of word
inc di ; increase wordcount
jmp scanloop4 ; locate begin of next word
done1: cmp ax,0101h ; check if end-of-word
je done ; if not, we have finished
inc di ; increase wordcount
jmp done
done2: cmp ax,0100h ; check for one-letter word
jne done ; if not, we have finished
inc di ; increase wordcount
done: mov si,[bp+charflag]
mov [si],al
mov bx,[bp+wordcount]
mov ax,[bx]
mov dx,[bx+2]
add di,ax
adc dx,0
mov [bx],di
mov [bx+2],dx
pop di
pop si
pop bp
ret
_ScanBuffer endp
end
```
### Level 2: A New Perspective {#Heading11}