James Gregory
GitHub
commit
fd5e7e94ff
3 changed files with 165 additions and 165 deletions
0
Makefile
Executable file → Normal file
0
Makefile
Executable file → Normal file
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@ -475,33 +475,33 @@ ckloopsetup:
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mov dx,[esi] ;load most of 1st word to
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mov bl,[esi+2] ; checksum (last byte loaded in loop)
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dec ecx ;any more dwords to checksum?
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jz short ckloopend ;no
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jz short ckloopend ;no
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ckloop:
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mov bh,[esi+3] ;cycle 1 U-pipe
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add esi,4 ;cycle 1 V-pipe
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shl ebx,16 ;cycle 2 U-pipe
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;cycle 2 V-pipe idle
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; (register contention)
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or ebx,edx ;cycle 3 U-pipe
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mov dl,[esi] ;cycle 3 V-pipe
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add eax,ebx ;cycle 4 U-pipe
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mov bl,[esi+2] ;cycle 4 V-pipe
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adc eax,0 ;cycle 5 U-pipe
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mov dh,[esi+1] ;cycle 5 V-pipe
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dec ecx ;cycle 6 U-pipe
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jnz ckloop ;cycle 6 V-pipe
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mov bh,[esi+3] ;cycle 1 U-pipe
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add esi,4 ;cycle 1 V-pipe
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shl ebx,16 ;cycle 2 U-pipe
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;cycle 2 V-pipe idle
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; (register contention)
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or ebx,edx ;cycle 3 U-pipe
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mov dl,[esi] ;cycle 3 V-pipe
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add eax,ebx ;cycle 4 U-pipe
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mov bl,[esi+2] ;cycle 4 V-pipe
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adc eax,0 ;cycle 5 U-pipe
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mov dh,[esi+1] ;cycle 5 V-pipe
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dec ecx ;cycle 6 U-pipe
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jnz ckloop ;cycle 6 V-pipe
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ckloopend:
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mov bh,[esi+3] ;checksum the last dword
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add ax,dx
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adc ax,bx
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adc ax,0
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mov bh,[esi+3] ;checksum the last dword
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add ax,dx
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adc ax,bx
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adc ax,0
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mov edx,eax ;compress the 32-bit checksum
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shr edx,16 ; into a 16-bit checksum
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add ax,dx
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adc eax,0
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mov edx,eax ;compress the 32-bit checksum
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shr edx,16 ; into a 16-bit checksum
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add ax,dx
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adc eax,0
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ckloopdone:
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```
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@ -598,29 +598,29 @@ more registers.
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jz short ckloopdone ;no, done
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add esi,4 ;point to the next dword
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noodddword:
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mov edx,[esi] ;preload the first dword
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mov ebx,[esi+4] ;preload the second dword
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dec ecx ;we'll do 1 checksum outside the loop
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jz short ckloopend ;only 1 checksum to do
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add esi,8 ;point to the next dword
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mov edx,[esi] ;preload the first dword
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mov ebx,[esi+4] ;preload the second dword
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dec ecx ;we'll do 1 checksum outside the loop
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jz short ckloopend ;only 1 checksum to do
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add esi,8 ;point to the next dword
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ckloop:
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add eax,edx ;cycle 1 U-pipe
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mov edx,[esi] ;cycle 1 V-pipe
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adc eax,ebx ;cycle 2 U-pipe
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mov ebx,[esi+4] ;cycle 2 V-pipe
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adc eax,0 ;cycle 3 U-pipe
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add esi,8 ;cycle 3 V-pipe
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dec ecx ;cycle 4 U-pipe
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jnz ckloop ;cycle 4 V-pipe
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add eax,edx ;cycle 1 U-pipe
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mov edx,[esi] ;cycle 1 V-pipe
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adc eax,ebx ;cycle 2 U-pipe
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mov ebx,[esi+4] ;cycle 2 V-pipe
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adc eax,0 ;cycle 3 U-pipe
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add esi,8 ;cycle 3 V-pipe
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dec ecx ;cycle 4 U-pipe
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jnz ckloop ;cycle 4 V-pipe
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ckloopend:
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add eax,edx ;checksum the last two dwords
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add eax,edx ;checksum the last two dwords
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adc eax,ebx
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adc eax,0
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ckloopdone:
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mov edx,eax ;compress the 32-bit checksum
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shr edx,16 ; into a 16-bit checksum
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mov edx,eax ;compress the 32-bit checksum
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shr edx,16 ; into a 16-bit checksum
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add ax,dx
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adc eax,0
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```
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@ -68,29 +68,29 @@ BufSeg dw ? ;buffer segment
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EndMrk db ? ;marker for the end of the stack frame
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OnStack ends
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;
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ClearS proc near
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push bp ;save caller's BP
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mov bp,sp ;point to stack frame
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cmp word ptr [bp].BufSeg,0 ;skip the fill if a null
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jne Start ; pointer is passed
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cmp word ptr [bp].BufOfs,0
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je Bye
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Start: cld ;make STOSW count up
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mov ax,[bp].Attrib ;load AX with attribute parameter
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and ax,0ff00h ;prepare for merging with fill char
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mov bx,[bp].Filler ;load BX with fill char
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and bx,0ffh ;prepare for merging with attribute
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or ax,bx ;combine attribute and fill char
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mov bx,[bp].BufOfs ;load DI with target buffer offset
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mov di,bx
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mov bx,[bp].BufSeg ;load ES with target buffer segment
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mov es,bx
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mov cx,[bp].BufSize ;load CX with buffer size
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rep stosw ;fill the buffer
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Bye:mov sp,bp ;restore original stack pointer
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pop bp ; and caller's BP
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ret EndMrk-RetAddr-2 ;return, clearing the parms from the stack
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ClearS endp
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ClearS proc near
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push bp ;save caller's BP
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mov bp,sp ;point to stack frame
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cmp word ptr [bp].BufSeg,0 ;skip the fill if a null
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jne Start ; pointer is passed
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cmp word ptr [bp].BufOfs,0
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je Bye
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Start: cld ;make STOSW count up
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mov ax,[bp].Attrib ;load AX with attribute parameter
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and ax,0ff00h ;prepare for merging with fill char
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mov bx,[bp].Filler ;load BX with fill char
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and bx,0ffh ;prepare for merging with attribute
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or ax,bx ;combine attribute and fill char
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mov bx,[bp].BufOfs ;load DI with target buffer offset
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mov di,bx
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mov bx,[bp].BufSeg ;load ES with target buffer segment
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mov es,bx
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mov cx,[bp].BufSize ;load CX with buffer size
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rep stosw ;fill the buffer
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Bye: mov sp,bp ;restore original stack pointer
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pop bp ; and caller's BP
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ret EndMrk-RetAddr-2 ;return, clearing the parms from the stack
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ClearS endp
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```
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The first thing you'll notice about Listing 22.1 is that `ClearS` uses
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@ -121,27 +121,27 @@ DI directly as shown in Listing 22.2.
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**LISTING 22.2 L22-2.ASM**
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```nasm
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ClearS proc near
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push bp ;save caller's BP
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mov bp,sp ;point to stack frame
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cmp word ptr [bp].BufSeg,0 ;skip the fill if a null
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jne Start ; pointer is passed
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cmp word ptr [bp].BufOfs,0
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je Bye
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ClearS proc near
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push bp ;save caller's BP
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mov bp,sp ;point to stack frame
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cmp word ptr [bp].BufSeg,0 ;skip the fill if a null
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jne Start ; pointer is passed
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cmp word ptr [bp].BufOfs,0
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je Bye
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Start: cld ;make STOSW count up
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mov ax,[bp].Attrib ;load AX with attribute parameter
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and ax,0ff00h ;prepare for merging with fill char
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mov bx,[bp].Filler ;load BX with fill char
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and bx,0ffh ;prepare for merging with attribute
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or ax,bx ;combine attribute and fill char
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mov di,[bp].BufOfs ;load DI with target buffer offset
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mov es,[bp].BufSeg ;load ES with target buffer segment
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mov cx,[bp].BufSize ;load CX with buffer size
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rep stosw ;fill the buffer
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mov ax,[bp].Attrib ;load AX with attribute parameter
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and ax,0ff00h ;prepare for merging with fill char
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mov bx,[bp].Filler ;load BX with fill char
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and bx,0ffh ;prepare for merging with attribute
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or ax,bx ;combine attribute and fill char
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mov di,[bp].BufOfs ;load DI with target buffer offset
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mov es,[bp].BufSeg ;load ES with target buffer segment
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mov cx,[bp].BufSize ;load CX with buffer size
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rep stosw ;fill the buffer
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Bye:
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pop bp ;restore caller's BP
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ret EndMrk-RetAddr-2 ;return, clearing the parms from the stack
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ClearS endp
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pop bp ;restore caller's BP
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ret EndMrk-RetAddr-2 ;return, clearing the parms from the stack
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ClearS endp
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```
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(The `OnStack` structure definition doesn't change in any of our
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@ -158,27 +158,27 @@ loading ES and DI as shown in Listing 22.3.
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**LISTING 22.3 L22-3.ASM**
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```nasm
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ClearS proc near
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push bp ;save caller's BP
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mov bp,sp ;point to stack frame
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cmp word ptr [bp].BufSeg,0 ;skip the fill if a null
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jne Start ; pointer is passed
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cmp word ptr [bp].BufOfs,0
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je Bye
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ClearS proc near
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push bp ;save caller's BP
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mov bp,sp ;point to stack frame
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cmp word ptr [bp].BufSeg,0 ;skip the fill if a null
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jne Start ; pointer is passed
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cmp word ptr [bp].BufOfs,0
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je Bye
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Start: cld ;make STOSW count up
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mov ax,[bp].Attrib ;load AX with attribute parameter
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and ax,0ff00h ;prepare for merging with fill char
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mov bx,[bp].Filler ;load BX with fill char
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and bx,0ffh ;prepare for merging with attribute
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or ax,bx ;combine attribute and fill char
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les di,dword ptr [bp].BufOfs ;load ES:DI with target buffer
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mov ax,[bp].Attrib ;load AX with attribute parameter
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and ax,0ff00h ;prepare for merging with fill char
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mov bx,[bp].Filler ;load BX with fill char
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and bx,0ffh ;prepare for merging with attribute
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or ax,bx ;combine attribute and fill char
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les di,dword ptr [bp].BufOfs ;load ES:DI with target buffer
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;segment:offset
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mov cx,[bp].BufSize ;load CX with buffer size
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rep stosw ;fill the buffer
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mov cx,[bp].BufSize ;load CX with buffer size
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rep stosw ;fill the buffer
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Bye:
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pop bp ;restore caller's BP
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ret EndMrk-RetAddr-2 ;return, clearing the parms from the stack
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ClearS endp
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pop bp ;restore caller's BP
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ret EndMrk-RetAddr-2 ;return, clearing the parms from the stack
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ClearS endp
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```
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That's good for another three bytes. We're down to 43 bytes, and
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@ -190,27 +190,27 @@ values as shown in Listing 22.4.
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**LISTING 22.4 L22-4.ASM**
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ClearS proc near
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push bp ;save caller's BP
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mov bp,sp ;point to stack frame
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cmp word ptr [bp].BufSeg,0 ;skip the fill if a null
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jne Start ; pointer is passed
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cmp word ptr [bp].BufOfs,0
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je Bye
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Start: cld ;make STOSW count up
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mov ax,[bp].Attrib ;load AX with attribute parameter
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sub al,al ;prepare for merging with fill char
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mov bx,[bp].Filler ;load BX with fill char
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sub bh,bh ;prepare for merging with attribute
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or ax,bx ;combine attribute and fill char
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les di,dword ptr [bp].BufOfs ;load ES:DI with target buffer
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;segment:offset
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mov cx,[bp].BufSize ;load CX with buffer size
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rep stosw ;fill the buffer
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ClearS proc near
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push bp ;save caller's BP
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mov bp,sp ;point to stack frame
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cmp word ptr [bp].BufSeg,0 ;skip the fill if a null
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jne Start ; pointer is passed
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cmp word ptr [bp].BufOfs,0
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je Bye
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Start: cld ;make STOSW count up
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mov ax,[bp].Attrib ;load AX with attribute parameter
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sub al,al ;prepare for merging with fill char
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mov bx,[bp].Filler ;load BX with fill char
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sub bh,bh ;prepare for merging with attribute
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or ax,bx ;combine attribute and fill char
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les di,dword ptr [bp].BufOfs ;load ES:DI with target buffer
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;segment:offset
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mov cx,[bp].BufSize ;load CX with buffer size
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rep stosw ;fill the buffer
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Bye:
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pop bp ;restore caller's BP
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ret EndMrk-RetAddr-2 ;return, clearing the parms from the stack
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ClearS endp
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pop bp ;restore caller's BP
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ret EndMrk-RetAddr-2 ;return, clearing the parms from the stack
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ClearS endp
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Now we're down to 40 bytes—more than 20 percent smaller than the
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original code. That's pretty much it for simple instruction
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@ -232,23 +232,23 @@ shows the new code.
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**LISTING 22.5 L22-5.ASM**
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```nasm
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ClearS proc near
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push bp ;save caller's BP
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mov bp,sp ;point to stack frame
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cmp word ptr [bp].BufSeg,0 ;skip the fill if a null
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jne Start ; pointer is passed
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cmp word ptr [bp].BufOfs,0
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je Bye
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Start: cld ;make STOSW count up
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mov ah,byte ptr [bp].Attrib[1];load AH with attribute
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mov al,byte ptr [bp].Filler ;load AL with fill char
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les di,dword ptr [bp].BufOfs ;load ES:DI with target buffer segment:offset
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mov cx,[bp].BufSize ;load CX with buffer size
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rep stosw ;fill the buffer
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ClearS proc near
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push bp ;save caller's BP
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mov bp,sp ;point to stack frame
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cmp word ptr [bp].BufSeg,0 ;skip the fill if a null
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jne Start ; pointer is passed
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cmp word ptr [bp].BufOfs,0
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je Bye
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Start: cld ;make STOSW count up
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mov ah,byte ptr [bp].Attrib[1] ;load AH with attribute
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mov al,byte ptr [bp].Filler ;load AL with fill char
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les di,dword ptr [bp].BufOfs ;load ES:DI with target buffer segment:offset
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mov cx,[bp].BufSize ;load CX with buffer size
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rep stosw ;fill the buffer
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Bye:
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pop bp ;restore caller's BP
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ret EndMrk-RetAddr-2 ;return, clearing the parms from the stack
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ClearS endp
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pop bp ;restore caller's BP
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ret EndMrk-RetAddr-2 ;return, clearing the parms from the stack
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ClearS endp
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```
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(We could get rid of yet another instruction by having the calling code
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@ -266,22 +266,22 @@ shown in Listing 22.6.
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**LISTING 22.6 L22-6.ASM**
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```nasm
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ClearS proc near
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push bp ;save caller's BP
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mov bp,sp ;point to stack frame
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les di,dword ptr [bp].BufOfs ;load ES:DI with target buffer;segment:offset
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mov ax,es ;put segment where we can test it
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or ax,di ;is it a null pointer?
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je Bye ;yes, so we're done
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Start: cld ;make STOSW count up
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mov ah,byte ptr [bp].Attrib[1];load AH with attribute
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mov al,byte ptr [bp].Filler ;load AL with fill char
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mov cx,[bp].BufSize ;load CX with buffer size
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rep stosw ;fill the buffer
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ClearS proc near
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push bp ;save caller's BP
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mov bp,sp ;point to stack frame
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les di,dword ptr [bp].BufOfs ;load ES:DI with target buffer;segment:offset
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mov ax,es ;put segment where we can test it
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or ax,di ;is it a null pointer?
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je Bye ;yes, so we're done
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Start: cld ;make STOSW count up
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mov ah,byte ptr [bp].Attrib[1] ;load AH with attribute
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mov al,byte ptr [bp].Filler ;load AL with fill char
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mov cx,[bp].BufSize ;load CX with buffer size
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rep stosw ;fill the buffer
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Bye:
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pop bp ;restore caller's BP
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ret EndMrk-RetAddr-2 ;return, clearing the parms from the stack
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ClearS endp
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pop bp ;restore caller's BP
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ret EndMrk-RetAddr-2 ;return, clearing the parms from the stack
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ClearS endp
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```
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Well. Now we're down to 28 bytes, having reduced the size of this
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@ -327,22 +327,22 @@ With that problem dealt with, Listing 22.7 shows the Zenned version of
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**LISTING 22.7 L22-7.ASM**
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```nasm
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ClearS procnear
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pop dx ;get the return address
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pop ax ;put fill char into AL
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pop bx ;get the attribute
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mov ah,bh ;put attribute into AH
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pop cx ;get the buffer size
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pop di ;get the offset of the buffer origin
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pop es ;get the segment of the buffer origin
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mov bx,es ;put the segment where we can test it
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or bx,di ;null pointer?
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je Bye ;yes, so we're done
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cld ;make STOSW count up
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rep stosw ;do the string store
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ClearS proc near
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pop dx ;get the return address
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pop ax ;put fill char into AL
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pop bx ;get the attribute
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mov ah,bh ;put attribute into AH
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pop cx ;get the buffer size
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pop di ;get the offset of the buffer origin
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pop es ;get the segment of the buffer origin
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mov bx,es ;put the segment where we can test it
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or bx,di ;null pointer?
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je Bye ;yes, so we're done
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cld ;make STOSW count up
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rep stosw ;do the string store
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Bye:
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jmp dx ;return to the calling code
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ClearS endp
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jmp dx ;return to the calling code
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ClearS endp
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```
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At long last, we're down to the bare metal. This version of `ClearS`
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