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James Gregory 2013-12-31 11:38:48 +11:00
commit f658bfbb40
203 changed files with 26546 additions and 25801 deletions
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88
22-02.md
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@ -12,27 +12,29 @@ pages: 417-418
**LISTING 22.2 L22-2.ASM**
ClearS proc near
push bp ;save caller's BP
mov bp,sp ;point to stack frame
cmp word ptr [bp].BufSeg,0 ;skip the fill if a null
jne Start ; pointer is passed
cmp word ptr [bp].BufOfs,0
je Bye
Start: cld ;make STOSW count up
mov ax,[bp].Attrib ;load AX with attribute parameter
and ax,0ff00h ;prepare for merging with fill char
mov bx,[bp].Filler ;load BX with fill char
and bx,0ffh ;prepare for merging with attribute
or ax,bx ;combine attribute and fill char
mov di,[bp].BufOfs ;load DI with target buffer offset
mov es,[bp].BufSeg ;load ES with target buffer segment
mov cx,[bp].BufSize ;load CX with buffer size
rep stosw ;fill the buffer
Bye:
pop bp ;restore caller's BP
ret EndMrk-RetAddr-2 ;return, clearing the parms from the stack
ClearS endp
```nasm
ClearS proc near
push bp ;save caller's BP
mov bp,sp ;point to stack frame
cmp word ptr [bp].BufSeg,0 ;skip the fill if a null
jne Start ; pointer is passed
cmp word ptr [bp].BufOfs,0
je Bye
Start: cld ;make STOSW count up
mov ax,[bp].Attrib ;load AX with attribute parameter
and ax,0ff00h ;prepare for merging with fill char
mov bx,[bp].Filler ;load BX with fill char
and bx,0ffh ;prepare for merging with attribute
or ax,bx ;combine attribute and fill char
mov di,[bp].BufOfs ;load DI with target buffer offset
mov es,[bp].BufSeg ;load ES with target buffer segment
mov cx,[bp].BufSize ;load CX with buffer size
rep stosw ;fill the buffer
Bye:
pop bp ;restore caller's BP
ret EndMrk-RetAddr-2 ;return, clearing the parms from the stack
ClearS endp
```
(The **OnStack** structure definition doesn't change in any of our
examples, so I'm not going clutter up this chapter by reproducing it for
@ -47,27 +49,29 @@ loading ES and DI as shown in Listing 22.3.
**LISTING 22.3 L22-3.ASM**
ClearS proc near
push bp ;save caller's BP
mov bp,sp ;point to stack frame
cmp word ptr [bp].BufSeg,0 ;skip the fill if a null
jne Start ; pointer is passed
cmp word ptr [bp].BufOfs,0
je Bye
Start: cld ;make STOSW count up
mov ax,[bp].Attrib ;load AX with attribute parameter
and ax,0ff00h ;prepare for merging with fill char
mov bx,[bp].Filler ;load BX with fill char
and bx,0ffh ;prepare for merging with attribute
or ax,bx ;combine attribute and fill char
les di,dword ptr [bp].BufOfs ;load ES:DI with target buffer
;segment:offset
mov cx,[bp].BufSize ;load CX with buffer size
rep stosw ;fill the buffer
Bye:
pop bp ;restore caller's BP
ret EndMrk-RetAddr-2 ;return, clearing the parms from the stack
ClearS endp
```nasm
ClearS proc near
push bp ;save caller's BP
mov bp,sp ;point to stack frame
cmp word ptr [bp].BufSeg,0 ;skip the fill if a null
jne Start ; pointer is passed
cmp word ptr [bp].BufOfs,0
je Bye
Start: cld ;make STOSW count up
mov ax,[bp].Attrib ;load AX with attribute parameter
and ax,0ff00h ;prepare for merging with fill char
mov bx,[bp].Filler ;load BX with fill char
and bx,0ffh ;prepare for merging with attribute
or ax,bx ;combine attribute and fill char
les di,dword ptr [bp].BufOfs ;load ES:DI with target buffer
;segment:offset
mov cx,[bp].BufSize ;load CX with buffer size
rep stosw ;fill the buffer
Bye:
pop bp ;restore caller's BP
ret EndMrk-RetAddr-2 ;return, clearing the parms from the stack
ClearS endp
```
That's good for another three bytes. We're down to 43 bytes, and
counting.