Misc/abrash-black-book
Watch
1
0
Fork
You've already forked abrash-black-book
 0
Code Issues Pull requests Projects Releases Packages Wiki Activity Actions

Replace invalid characters with HTML entities

Browse source 
— with —
’ with ’
+ with +
× with x
ç with ç
“ with “
” with ”
‘ with ‘
• with •
– with -
µ with µ
† with †
Fix C++
θ with θ
Yen symbol instead of times
Fix broken apos
Bullet again
E-circumflex
This commit is contained in:
James Gregory 2013-12-30 12:50:32 +11:00
commit 500e7f5654
353 changed files with 5091 additions and 5091 deletions
Download patch file Download diff file Expand all files Collapse all files

44
07-04.html
View file

@ -48,21 +48,21 @@
.data
; Sample string to search through.
SampleStringlabelbyte
db ‘This is a sample string of a long enough length ’
db ‘so that raw searching speed can outweigh any ’
db ‘extra set-up time that may be required.’,0
db ‘This is a sample string of a long enough length ’
db ‘so that raw searching speed can outweigh any ’
db ‘extra set-up time that may be required.’,0
SAMPLE_STRING_LENGTH equ $-SampleString
; User prompt.
Prompt db ‘Enter character to search for:$’
Prompt db ‘Enter character to search for:$’
; Result status messages.
ByteFoundMsg db 0dh,0ah
db ‘Specified byte found.’,0dh,0ah,‘$’
db ‘Specified byte found.’,0dh,0ah,‘$’
ZeroByteFoundMsg db 0dh,0ah
db ‘Zero byte encountered.’, 0dh, 0ah, ‘$’
db ‘Zero byte encountered.’, 0dh, 0ah, ‘$’
NoByteFoundMsg db 0dh,0ah
db ‘Buffer exhausted with no match.’, 0dh, 0ah, ‘$’
db ‘Buffer exhausted with no match.’, 0dh, 0ah, ‘$’
; Table of initial, possibly partial loop entry points for
; SearchMaxLength.
@ -87,12 +87,12 @@ Start proc near
call SearchMaxLength ;search the buffer
mov dx,offset ByteFoundMsg ;assume we found the byte
jc PrintStatus ;we did find the byte
;we didn’t find the byte, figure out
;we didn’t find the byte, figure out
;whether we found a zero byte or
;ran out of buffer
mov dx,offset NoByteFoundMsg
;assume we didn’t find a zero byte
jcxz PrintStatus ;we didn’t find a zero byte
;assume we didn’t find a zero byte
jcxz PrintStatus ;we didn’t find a zero byte
mov dx,offset ZeroByteFoundMsg ;we found a zero byte
PrintStatus:
mov ah,9 ;DOS print string function
@ -134,42 +134,42 @@ SearchMaxLengthLoop:
SearchMaxLengthEntry4:
lodsb ;get the next byte
cmp al,ah ;is this the byte we want?
jz ByteFound ;yes, we’re done with success
jz ByteFound ;yes, we’re done with success
and al,al ;is this the terminating 0 byte?
jz ByteNotFound ;yes, we’re done with failure
jz ByteNotFound ;yes, we’re done with failure
SearchMaxLengthEntry3:
lodsb ;get the next byte
cmp al,ah ;is this the byte we want?
jz ByteFound ;yes, we’re done with success
jz ByteFound ;yes, we’re done with success
and al,al ;is this the terminating 0 byte?
jz ByteNotFound ;yes, we’re done with failure
jz ByteNotFound ;yes, we’re done with failure
SearchMaxLengthEntry2:
lodsb ;get the next byte
cmp al,ah ;is this the byte we want?
jz ByteFound ;yes, we’re done with success
jz ByteFound ;yes, we’re done with success
and al,al ;is this the terminating 0 byte?
jz ByteNotFound ;yes, we’re done with failure
jz ByteNotFound ;yes, we’re done with failure
SearchMaxLengthEntry1:
lodsb ;get the next byte
cmp al,ah ;is this the byte we want?
jz ByteFound ;yes, we’re done with success
jz ByteFound ;yes, we’re done with success
and al,al ;is this the terminating 0 byte?
jz ByteNotFound ;yes, we’re done with failure
loop SearchMaxLengthLoop ;it’s neither, so check the next
jz ByteNotFound ;yes, we’re done with failure
loop SearchMaxLengthLoop ;it’s neither, so check the next
; four bytes, if any
ByteNotFound:
clc ;return “not found” status
clc ;return “not found” status
ret
ByteFound:
dec si ;point back to the location at which
; we found the searched-for byte
stc ;return “found” status
stc ;return “found” status
ret
SearchMaxLengthendp
end Start
</PRE>
<!-- END CODE //-->
<P>How much difference? Listing 7.2 runs in 121 &#181;s&#151;40 percent faster than Listing 7.1, even though Listing 7.2 still uses <B>LOOP</B> rather than <B>DEC CX/JNZ.</B> (The loop in Listing 7.2 could be unrolled further, too; it&#146;s just a question of how much more memory you want to trade for ever-decreasing performance benefits.) That&#146;s typical of local optimization; it won&#146;t often yield the order-of-magnitude improvements that algorithmic improvements can produce, but it can get you a critical 50 percent or 100 percent improvement when you&#146;ve exhausted all other avenues.</P>
<P>How much difference? Listing 7.2 runs in 121 &micro;s&mdash;40 percent faster than Listing 7.1, even though Listing 7.2 still uses <B>LOOP</B> rather than <B>DEC CX/JNZ.</B> (The loop in Listing 7.2 could be unrolled further, too; it&rsquo;s just a question of how much more memory you want to trade for ever-decreasing performance benefits.) That&rsquo;s typical of local optimization; it won&rsquo;t often yield the order-of-magnitude improvements that algorithmic improvements can produce, but it can get you a critical 50 percent or 100 percent improvement when you&rsquo;ve exhausted all other avenues.</P>
<TABLE WIDTH="100%"><TD ALIGN="LEFT" VALIGN="TOP" WIDTH="5%"><IMG SRC="images/i.jpg"><TD ALIGN="LEFT" VALIGN="TOP" WIDTH="95%"><SMALL><I>The point is simply this: You can gain far more by stepping back a bit and thinking of the fastest overall way for the CPU to perform a task than you can by saving a cycle here or there using different instructions. Try to think at the level of sequences of instructions rather than individual instructions, and learn to treat x86 instructions as building blocks with unique characteristics rather than as instructions dedicated to specific tasks.</I></SMALL>
</TABLE>
<P><BR></P>