Shareware Overload/ShartewareOverload.cdr/database/db3tips2.zip/DCRUNCH.TXT

Text File | 1986-07-01 | 11KB | 323 lines

                    dCRUNCH for Program Speed
              (PC Magazine Vol 5 No 13 Power User)

     In both "Pseudo Compiler for dBASE II" (PC Mag Vol 5 No 5 Power
User) and "dBASE Speed Tips" (PC Mag Vol 5 No 1 Power User), the point
is made that dBASE programs will execute faster if leading and trailing
spaces, blank lines, and "*" lines are stripped out and if everything
(except quoted text) is capitalized.  (See the file DB3MISC.TXT for
the articles cited here.)
     To facilitate the necessary file preparation, dCRUNCH.BAT and
dSTRIP.COM will convert a 64K command file in under 6 seconds.  Before
running programs through the DOS filter, edit out any single apostrophes
inside NOTE or TEXT/ENDTEXT statements, since capitalization is based
on pairs of apostrophes, double quote, or brackets.  Note also that
everything inside a TEXT/ENDTEXT statement will be capitalized and
left-justified unless you first enclose it in quotes, then edit out
the quotes later.
     The syntax for the command is:

DCRUNCH [d:][path][filename]

and you should omit the .PRG filename extension.
     dBASE's interpreter is its weakest (slowest) link.  When a command
is issued, the interpreter 1) parses the full command line; 2) discards
leading spaces; 3) indexes to the first space to identify the verb;
4) truncates the string if it's longer than four characters; 5) converts
it to uppercase; 6) searches its lookup table of initial verbs; and,
7) gets down to business.  If you write a long NOTE or "*" comment, the
interpreter looks at every byte, savors a delicate sample, then spits
it out.  The same applies when you add a comment after ENDIF or ENDDO,
or when you indent command lines for legibility.
     Take, for example, this simple iterative loop:

variable_x=0
DO WHILE variable_x<1000
     variable_x=variable_x+1
     *This is a long comment line
     *explaining what's going on
ENDDO

     dCRUNCH shortens processing of this loop over 25 percent -- from
58 to 42 seconds.  The biggest offender is the"*" line -- 13 seconds;
a long comment tacked on to the ENDDO will have the same effect.
Shortening "variable_x" to "x" shaves another 6 seconds.
     There is no measurable difference is one blank line is added, but
a large overhead begins to accumulate with each additional blank line.
Five blank lines increase execution time of 1,000 loops by 11 seconds.
     dCRUNCH's side effects are substantial.  A program that is all-
capitalized and left-justified without comments or mnemonic variable
names is awful to read and a nightmare to modify 6 months later.  And,
in most applications, a few extra milliseconds inside a loop is the
least of your problems.  But if you need maximum speed inside an
intensive loop -- like passing each record in a file -- dCRUNCH is
just the ticket.

- - - - -
dCRUNCH.BAT:

ECHO OFF
REM dCRUNCH.BAT   Speeds dBASE routines.   Calls dSTRIP.COM
IF %1/==/ GOTO noparm
IF NOT EXIST dstrip.com GOTO nocom
IF EXIST %1.prg GOTO strip
ECHO -----
ECHO File %1.PRG not found
IF EXIST %1 ECHO Please specify the file without .PRG extension
GOTO noparm
:strip
IF NOT EXIST %1.prk GOTO work
ECHO -----
ECHO A back-up file %1.PRK already exists and will be overwritten.
ECHO Hit CTRL-BREAK followed by Y to interrupt or ...
PAUSE
DEL %1.prg
:work
ECHO Streamlining %1.prg.  Original version is saved as %1.prk
REN %1.prg %1.prk
dstrip <%1.prk >%1.prg
GOTO end
:noparm
ECHO SYNTAX:     DCRUNCH [d:][path][filename]   (omit ".prg" extension)
GOTO end
:nocom
ECHO File DSTRIP.COM not found.
:end

- - - - -
DSTRIP.ASM (to create DSTRIP.COM):

; DSTRIP - DOS filter to remove leading and trailing blanks, blank
;          lines and comment lines from dBASE command files, and to
;          capitalize text not in quotation marks.
;
comseg  segment para public 'code'
        assume  cs:comseg,ds:comseg,es:comseg,ss:comseg
        org     100h
start   proc    far
        cld
        mov     bl,00000001b    ;the bits in the BL register will hold
                                ;the following information when set to 1:
                                ;0-bit  only tabs and blanks encountered
                                ;       in current line
                                ;1-bit  a '*' encountered as first
                                ;       character of line
                                ;4-bit  char inside 'single' quotes
                                ;5-bit  char inside "double" quotes
                                ;6-bit  last char was linefeed
                                ;7-bit  last char in *-line was a ';'
        xor     dx,dx           ;DX will count blanks/tabs after a char
load:   push    bx              ;save registers and
        push    dx
        mov     dx,offset data  ;read into memory
        mov     cx,64000        ;64K bytes
        xor     bx,bx           ;from standard input
        mov     ah,3fh          ;with DOS function call
        int     21h
        pop     dx              ;restore registers
        pop     bx
        or      ax,ax           ;AX has number of bytes read; test for 0
        jnz     load0
        jmp     done
load0:  mov     cx,ax           ;move count into CX
        mov     si,offset data  ;and position index registers for
        mov     di,offset data  ;a string move
scan0:  lodsb                   ;fetch a byte into AL
        cmp     al,26           ;end of file?
        jz      store           ;if so, store and get out
        test    bl,01000000b    ;LF on previous fetch?
        jz      next            ;if not, skip
        or      bl,1            ;set beginning of line bit
        and     bl,10111111b    ;and reset the LF bit
        test    bl,10000000b    ;a ';' at end of line?
        jnz     next0           ;if yes, skip
        and     bl,11111101b    ;otherwise reset '*'-bit
next0:  and     bl,01111111b    ;reset ';'-bit
next:   cmp     al,59           ;a ';'?
        jnz     next1           ;if not, skip
        or      bl,10000000b    ;set ';'-bit
        jmp     short next5     ;and do loop routine
next1:  cmp     al,32           ;blank?
        jz      count           ;if yes, check whether to count it
        cmp     al,09           ;tab?
        jnz     next2           ;if not, skip count
count:  test    bl,11b          ;are we at beginning of line or in a '*'-line?
        jnz     loop            ;if yes, loop and omit
        inc     dx              ;otherwise count the blank/tab
        jmp     short store     ;and store it
next2:  cmp     al,13           ;CR?
        jz      out             ;if yes go to end of line routine
next3:  cmp     al,10           ;LF?
        jnz     next4           ;if not, go on checking
        or      bl,01000000b    ;set end of line bit
        jmp     short out       ;and go to end of line routine
next4:  test    bl,1            ;have we seen any nonblank/tab char before?
        jz      next6           ;if yes, ignore the next step
        cmp     al,42           ;a '*'?
        jnz     next5           ;if not, skip
        or      bl,10b          ;otherwise set the '*'-bit
next5:  and     bl,11111110b    ;and in either case we have nonblank/tab char
next6:  xor     dx,dx           ;set blank/tab count to 0
out:    test    bl,11b          ;are we at beginning of line or in a '*'-line?
        jnz     loop            ;if so, ignore (includes CR/LF of blank lines)
        sub     di,dx           ;DX is non-zero only if we encountered a CR
        xor     dx,dx           ;reset DX to 0
        and     bl,01111111b    ;reset ';'-bit
caps0:  jmp     short caps      ;capitalize
store:  stosb                   ;store char
loop:   cmp     al,26           ;test for end of file
        loopnz  scan0           ;and loop for next fetch
        push    ax              ;save registers
        push    bx
        push    dx
        mov     dx,offset data  ;compute the numbers of bytes stored
        mov     cx,di
        sub     cx,dx           ;in CX, and
        mov     bx,01           ;write to standard output
        mov     ah,40h          ;with DOS function call
        int     21h
        pop     dx
        pop     bx
        pop     ax
        cmp     al,26           ;end of file?
        jz      done
        jmp     load            ;if not, read another 64K bytes
done:   int     20h             ;end program
caps:   cmp     al,39           ;single quote?
        jnz     quot            ;if not, check double quote
        test    bl,100000b      ;is double quote bit set?
        jnz     store           ;if yes, ignore
        xor     bl,010000b      ;(re-)set single quote bit
        jmp     short store
quot:   cmp     al,34           ;double quote?
        jnz     caps01          ;if not, skip
        xor     bl,00100000b    ;(re-)set double-quote bit
        jmp     short store
caps01: test    bl,00110000b    ;any quote-bits set?
        jnz     store           ;if so, don't capitalize
caps1:  cmp     al,97           ;below 'a'?
        jb      store           ;if so, leave it alone
caps2:  cmp     al,122          ;above 'z'?
        ja      store           ;if so, don't change
caps3:  and     al,5fh          ;otherwise capitalize
out2:   jmp     short store
start   endp
data:
comseg  ends
        end     start


- - - - -
     You can use DEBUG to create DSTRIP.COM by issuing the command:

DEBUG < DSTRIP.INP

with the following.  DEBUG will use DSTRIP.INP as its input to create
the .COM file.

N DSTRIP.COM
A
CLD
MOV     BL,01
XOR     DX,DX
PUSH    BX
PUSH    DX
MOV     DX,01CE
MOV     CX,FA00
XOR     BX,BX
MOV     AH,3F
INT     21
POP     DX
POP     BX
OR      AX,AX
JNZ     011C
JMP     01A4
MOV     CX,AX
MOV     SI,01CE
MOV     DI,01CE
LODSB
CMP     AL,1A
JZ      0184
TEST    BL,40
JZ      013F
OR      BL,01
AND     BL,BF
TEST    BL,80
JNZ     013C
AND     BL,FD
AND     BL,7F
CMP     AL,3B
JNZ     0148
OR      BL,80
JMP     0171
CMP     AL,20
JZ      0150
CMP     AL,09
JNZ     0158
TEST    BL,03
JNZ     0185
INC     DX
JMP     0184
CMP     AL,0D
JZ      0176
CMP     AL,0A
JNZ     0165
OR      BL,40
JMP     0176
TEST    BL,01
JZ      0174
CMP     AL,2A
JNZ     0171
OR      BL,02
AND     BL,FE
XOR     DX,DX
TEST    BL,03
JNZ     0185
SUB     DI,DX
XOR     DX,DX
AND     BL,7F
JMP     01A6
STOSB
CMP     AL,1A
LOOPNZ  0124
PUSH    AX
PUSH    BX
PUSH    DX
MOV     DX,01CE
MOV     CX,DI
SUB     CX,DX
MOV     BX,0001
MOV     AH,40
INT     21
POP     DX
POP     BX
POP     AX
CMP     AL,1A
JZ      01A4
JMP     0105
INT     20
CMP     AL,27
JNZ     01B4
TEST    BL,20
JNZ     0184
XOR     BL,10
JMP     0184
CMP     AL,22
JNZ     01BD
XOR     BL,20
JMP     0184
TEST    BL,30
JNZ     0184
CMP     AL,61
JB      0184
CMP     AL,7A
JA      0184
AND     AL,5F
JMP     0184

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