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James Gregory 2013-12-31 11:38:48 +11:00
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03-09.md
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@ -12,67 +12,69 @@ pages: 067-070
**LISTING 3.7 LZTIME.BAT**
echo off
rem
rem *** Listing 3.7 ***
rem
rem ***************************************************************
rem * Batch file LZTIME.BAT, which builds and runs the *
rem * long-period Zen timer program LZTEST.EXE to time the code *
rem * named as the command-line parameter. Listing 3.5 must be *
rem * named LZTIMER.ASM, and Listing 3.6 must be named *
rem * LZTEST.ASM. To time the code in LST3-8, you'd type the *
rem * DOS command: *
rem * *
rem * lztime lst3-8 *
rem * *
rem * Note that MASM and LINK must be in the current directory or *
rem * on the current path in order for this batch file to work. *
rem * *
rem * This batch file can be speeded up by assembling LZTIMER.ASM *
rem * once, then removing the lines: *
rem * *
rem * masm lztimer; *
rem * if errorlevel 1 goto errorend *
rem * *
rem * from this file. *
rem * *
rem * By Michael Abrash *
rem ***************************************************************
rem
rem Make sure a file to test was specified.
rem
if not x%1==x goto ckexist
echo ***************************************************************
echo * Please specify a file to test. *
echo ***************************************************************
goto end
rem
rem Make sure the file exists.
rem
:ckexist
if exist %1 goto docopy
echo ***************************************************************
echo * The specified file, "%1," doesn't exist. *
echo ***************************************************************
goto end
rem
rem copy the file to measure to TESTCODE.
:docopy
copy %1 testcode
masm lztest;
if errorlevel 1 goto errorend
masm lztimer;
if errorlevel 1 goto errorend
link lztest+lztimer;
if errorlevel 1 goto errorend
lztest
goto end
:errorend
echo ***************************************************************
echo * An error occurred while building the long-period Zen timer. *
echo ***************************************************************
:end
```bat
echo off
rem
rem *** Listing 3.7 ***
rem
rem ***************************************************************
rem * Batch file LZTIME.BAT, which builds and runs the *
rem * long-period Zen timer program LZTEST.EXE to time the code *
rem * named as the command-line parameter. Listing 3.5 must be *
rem * named LZTIMER.ASM, and Listing 3.6 must be named *
rem * LZTEST.ASM. To time the code in LST3-8, you'd type the *
rem * DOS command: *
rem * *
rem * lztime lst3-8 *
rem * *
rem * Note that MASM and LINK must be in the current directory or *
rem * on the current path in order for this batch file to work. *
rem * *
rem * This batch file can be speeded up by assembling LZTIMER.ASM *
rem * once, then removing the lines: *
rem * *
rem * masm lztimer; *
rem * if errorlevel 1 goto errorend *
rem * *
rem * from this file. *
rem * *
rem * By Michael Abrash *
rem ***************************************************************
rem
rem Make sure a file to test was specified.
rem
if not x%1==x goto ckexist
echo ***************************************************************
echo * Please specify a file to test. *
echo ***************************************************************
goto end
rem
rem Make sure the file exists.
rem
:ckexist
if exist %1 goto docopy
echo ***************************************************************
echo * The specified file, "%1," doesn't exist. *
echo ***************************************************************
goto end
rem
rem copy the file to measure to TESTCODE.
:docopy
copy %1 testcode
masm lztest;
if errorlevel 1 goto errorend
masm lztimer;
if errorlevel 1 goto errorend
link lztest+lztimer;
if errorlevel 1 goto errorend
lztest
goto end
:errorend
echo ***************************************************************
echo * An error occurred while building the long-period Zen timer. *
echo ***************************************************************
:end
```
Listing 3.8 shows sample code that can be timed with the test-bed
program of Listing 3.6. Listing 3.8 measures the time required to
@ -81,38 +83,42 @@ the precision Zen timer to handle on the 8088.
**LISTING 3.8 LST3-8.ASM**
;
; Measures the performance of 20,000 loads of AL from
; memory. (Use by renaming to TESTCODE, which is
; included by LZTEST.ASM (Listing 3.6). LZTIME.BAT
; (Listing 3.7) does this, along with all assembly
; and linking.)
;
; Note: takes about ten minutes to assemble on a slow PC if
;you are using MASM
;
jmpSkip;jump around defined data
;
MemVardb?
;
Skip:
;
; Start timing.
;
callZTimerOn
;
rept20000
moval,[MemVar]
endm
;
; Stop timing.
;
callZTimerOff
```nasm
;
; Measures the performance of 20,000 loads of AL from
; memory. (Use by renaming to TESTCODE, which is
; included by LZTEST.ASM (Listing 3.6). LZTIME.BAT
; (Listing 3.7) does this, along with all assembly
; and linking.)
;
; Note: takes about ten minutes to assemble on a slow PC if
;you are using MASM
;
jmpSkip;jump around defined data
;
MemVardb?
;
Skip:
;
; Start timing.
;
callZTimerOn
;
rept20000
moval,[MemVar]
endm
;
; Stop timing.
;
callZTimerOff
```
When LZTIME.BAT is run on a PC with the following command line (assuming
the code in Listing 3.8 is the file LST3-8.ASM)
lztime lst3-8.asm
```sh
lztime lst3-8.asm
```
the result is 72,544 µs, or about 3.63 µs per load of AL from memory.
This is just slightly longer than the time per load of AL measured by
@ -147,4 +153,6 @@ lines from Listing 3.1 that must be changed. These changes convert the
code to use C-style external label names and the small model C code
segment. (In C++, use the "C" specifier, as in
extern "C" ZTimerOn(void);
```c
extern "C" ZTimerOn(void);
```