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Length: 24275 (0x5ed3)
Types: TextFile
Names: »SIDSAMPL.DOC«
└─⟦f18477172⟧ Bits:30003931/GEM_Develop_disk_1_CDOS.imd Disketter indleveret af Steffen Jensen (Piccolo/Piccoline)
└─⟦this⟧ »DOCU\SIDSAMPL.DOC«
SID-86 Sample Session
In the following sample session, the user interactively debugs a simple
program. Remarks in brackets explain the steps involved.
ÆType source file of program to test.Å
C>type sample.a86
;
; This program reads an ASCII file, breaking it up into "tokens",
; which are displayed on the console.
;
fcb equ 5ch
cr equ 0dh
lf equ 0ah
tab equ 09h
end_file equ 1ah
init:
mov dx,fcb
mov ah,15
int 21h
or al,al
jnz err
main_loop:
call collect_token
cmp token,end_file
jz done
call print_token
jmps main_loop
done:
retf
err: mov dx,offset nofile
call printm
jmp done
collect_token:
call get_char
call check_delim
jz col1
mov bx,token_len
mov tokenÆbxÅ,al
inc token_len
jmps collect_token
col1: ret
check_delim:
cmp al,cr
jz cret
cmp al,lf
jz cret
cmp al,tab
jz cret
cmp al,' '
cret: ret
get_char:
cmp buffptr, buffsize
jc get1
mov dx,offset buff
call setdta
mov dx,fcb
call readsec
mov buffptr,0
get1:
mov bx,buffptr
mov al,buffÆbxÅ
inc buffptr
ret
print_token:
mov cx,token_len
jcxz pr2
sub bx,bx
pr1: mov dl,tokenÆbxÅ
push cx
push bx
call conout
pop bx
pop cx
inc bx
dec cx
loop pr1
mov dl,cr
call conout
mov dl,lf
call conout
pr2:
ret
conout: mov ah,2
int 21h
ret
printm: mov ah,9
int 21h
ret
readsec:
mov ah,20
int 21h
ret
setdta: mov ah,26
int 21h
ret
dseg
nofile db 'NO FILE$'
buffsize equ 128
buffptr dw 0
buff rb buffsize
max_token equ 40
token_len rw 1
token rb max_token
end
ÆAssemble the file using the $LO option, which puts local symbols into
the object file.Å
C>rasm86 sample $lo
--------------------------------------------------
RASM-86 Relocating Assembler Version 1.0
Serial No. PPPP-OOOO-SSSSSS All Rights Reserved
Copyright (C) 1982,1983 Digital Research, Inc.
--------------------------------------------------
END OF PASS 1
END OF PASS 2
SEGMENTS
--------
00B4 DATA
00A7 CODE
END OF ASSEMBLY. NUMBER OF ERRORS: 0. USE FACTOR: 1%
ÆLink the object file to produce an executable (EXE) file and a symbol
table (SYM) file.Å
C>link86 sample
--------------------------------------------------
LINK-86 Linkage Editor Version 1.0
Serial No. PPPP-OOOO-SSSSSS All Rights Reserved
Copyright (C) 1982,1983 Digital Research, Inc.
--------------------------------------------------
CODE 000AC
DATA 001B4
USE FACTOR: 00%
ÆTEST.TEX has test data for SAMPLE.Å
C>type test.tex
Now is the time for all good men to come to the aid of their country.
ÆTry running SAMPLE on TEST.TEX.Å
C>sample test.tex
NowqPF1RwqBÆ
æ QR@ÅBUlF91Rwq C
æ#"F1RwqB Q0RH"ÅBUlG"!LH9"wN6"F"sdÅCUl
^7Qcv Hw&t#"R "!t9wa#
"!"@;:%v
!:%+"@wa#
"!"#Iüu!V#66
"8(Phå!"#V66
"8(PhüÅBUl0vhÅBUl0vv-
^7Q7vhüü
^7QcÅBUv8k6jht""
"7
lP^C
ÆThis does not look quite right. Load the EXE and SYM files under SID-
86 (the appropriate file types are assumed).Å
C>sid86 sample sample
--------------------------------------------------
SID-86 Symbolic Debugger Version 1.0
Serial No. PPPP-OOOO-SSSSSS All Rights Reserved
Copyright (C) 1983 Digital Research, Inc.
--------------------------------------------------
START END
0B5F:0000 0B5F:09FF
SYMBOLS
ÆList the symbols that SID-86 reads from SAMPLE.SYM.Å
#h
0009 TAB
001A END_FILE
000D CR
000A LF
005C FCB
0028 MAX_TOKEN
0000 NUMBERS
0010 MAIN_LOOP
00A2 READSEC
0005 INIT
004E CRET
0076 PRINT_TOKEN
0020 ERR
0040 CHECK_DELIM
001F DONE
0029 COLLECT_TOKEN
004F GET_CHAR
009D PRINTM
0098 CONOUT
0097 PR2
007E PR1
0069 GET1
003F COL1
00A7 SETDTA
0000 LABELS
018A TOKEN_LEN
0100 NOFILE
010A BUFF
0108 BUFFPTR
018C TOKEN
0000 VARIABLES
0000 SAMPLE
ÆDisassemble the beginning of the program.Å
#l
SAMPLE:
0B9F:0000 NOP
0B9F:0001 NOP
0B9F:0002 NOP
0B9F:0003 NOP
0B9F:0004 NOP
INIT:
0B9F:0005 MOV DX,005C .FCB
0B9F:0008 MOV AH,0F
0B9F:000A INT 21
0B9F:000C OR AL,AL
0B9F:000E JNZ 0020 .ERR
MAIN_LOOP:
0B9F:0010 CALL 0029 .COLLECT_TOKEN
0B9F:0013 CMP BYTE Æ018CÅ,1A .TOKEN
ÆStart the program with a breakpoint at MAIN_LOOP.Å
#g,10
NO FILE
PROGRAM TERMINATED NORMALLY
#^C
ÆOops! Forgot to tell SAMPLE the name of the file to process. Reload
the program.Å
C>sid86 sample sample
--------------------------------------------------
SID-86 Symbolic Debugger Version 1.0
Serial No. PPPP-OOOO-SSSSSS All Rights Reserved
Copyright (C) 1983 Digital Research, Inc.
--------------------------------------------------
START END
0B5F:0000 0B5F:09FF
SYMBOLS
ÆSet up the file name for SAMPLE to use.Å
#
itest.tex
ÆGo with breakpoint at 10H (MAIN_LOOP).Å
#g,10
*0B9F:0010 .MAIN_LOOP
ÆGot there this time! List next instructions.Å
#l
MAIN_LOOP:
0B9F:0010 CALL 0029 .COLLECT_TOKEN
0B9F:0013 CMP BYTE Æ018CÅ,1A .TOKEN
0B9F:0018 JZ 001F .DONE
0B9F:001A CALL 0076 .PRINT_TOKEN
0B9F:001D JMPS 0010 .MAIN_LOOP
DONE:
0B9F:001F RETF
ERR:
0B9F:0020 MOV DX,0100 .NOFILE
0B9F:0023 CALL 009D .PRINTM
0B9F:0026 JMP 001F .DONE
COLLECT_TOKEN:
0B9F:0029 CALL 004F .GET_CHAR
0B9F:002C CALL 0040 .CHECK_DELIM
0B9F:002F JZ 003F .COL1
ÆTrace without call to see the results of COLLECT_TOKEN without worrying
about what happens at lower levels.Å
#tw3
AX BX CX DX SP BP SI DI IP
--I--Z-P- 0F00 0BAA 0000 005C 037B 0000 0100 0100 0010
CALL 0029 .COLLECT_TOKEN
--I--Z-P- 1420 0003 0000 005C 037B 0000 0100 0100 0013
CMP BYTE Æ018CÅ,1A .TOKEN =00
--I-S-A-C 1420 0003 0000 005C 037B 0000 0100 0100 0018
JZ 001F .DONE
*0B9F:001A
ÆDisplay the contents of the TOKEN array.Å
#d.token,+f
0BAA:018C 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
................
ÆThe TOKEN array is empty! No wonder it does not work. Reload the
program.Å
#esample sample
START END
0B5F:0000 0B5F:09FF
SYMBOLS
#itest.tex
ÆGo up to MAIN_LOOP.Å
#g,10
*0B9F:0010 .MAIN_LOOP
#l,+9
MAIN_LOOP:
0B9F:0010 CALL 0029 .COLLECT_TOKEN
0B9F:0013 CMP BYTE Æ018CÅ,1A .TOKEN
0B9F:0018 JZ 001F .DONE
ÆThis time trace through COLLECT_TOKEN routine.Å
#t
AX BX CX DX SP BP SI DI IP
--I--Z-P- 0F00 0BAA 0000 005C 037B 0000 0100 0100 0010
CALL 0029 .COLLECT_TOKEN
*0B9F:0029 .COLLECT_TOKEN
#l
COLLECT_TOKEN:
0B9F:0029 CALL 004F .GET_CHAR
0B9F:002C CALL 0040 .CHECK_DELIM
0B9F:002F JZ 003F .COL1
0B9F:0031 MOV BX,Æ018AÅ .TOKEN_LEN
0B9F:0035 MOV 018CÆBXÅ,AL .TOKEN
0B9F:0039 INC WORD Æ018AÅ .TOKEN_LEN
0B9F:003D JMPS 0029 .COLLECT_TOKEN
COL1:
0B9F:003F RET
CHECK_DELIM:
0B9F:0040 CMP AL,0D .CR
0B9F:0042 JZ 004E .CRET
0B9F:0044 CMP AL,0A .LF
0B9F:0046 JZ 004E .CRET
ÆTrace through GET_CHAR routine.Å
#t
AX BX CX DX SP BP SI DI IP
--I--Z-P- 0F00 0BAA 0000 005C 0379 0000 0100 0100 0029
CALL 004F .GET_CHAR
*0B9F:004F .GET_CHAR
#l
GET_CHAR:
0B9F:004F CMP WORD Æ0108Å,0080 .BUFFPTR
0B9F:0055 JB 0069 .GET1
0B9F:0057 MOV DX,010A .BUFF
0B9F:005A CALL 00A7 .SETDTA
0B9F:005D MOV DX,005C .FCB
0B9F:0060 CALL 00A2 .READSEC
0B9F:0063 MOV WORD Æ0108Å,0000 .BUFFPTR
GET1:
0B9F:0069 MOV BX,Æ0108Å .BUFFPTR
0B9F:006D MOV AL,010AÆBXÅ .BUFF
0B9F:0071 INC WORD Æ0108Å .BUFFPTR
0B9F:0075 RET
PRINT_TOKEN:
0B9F:0076 MOV CX,Æ018AÅ .TOKEN_LEN
#t2
AX BX CX DX SP BP SI DI IP
--I--Z-P- 0F00 0BAA 0000 005C 0377 0000 0100 0100 004F
CMP WORD Æ0108Å,0080 .BUFFPTR =0000
--I-S---C 0F00 0BAA 0000 005C 0377 0000 0100 0100 0055
JB 0069 .GET1
*0B9F:0069 .GET1
#l
GET1:
0B9F:0069 MOV BX,Æ0108Å .BUFFPTR
0B9F:006D MOV AL,010AÆBXÅ .BUFF
0B9F:0071 INC WORD Æ0108Å .BUFFPTR
0B9F:0075 RET
PRINT_TOKEN:
0B9F:0076 MOV CX,Æ018AÅ .TOKEN_LEN
0B9F:007A JCXZ 0097 .PR2
0B9F:007C SUB BX,BX
PR1:
0B9F:007E MOV DL,018CÆBXÅ .TOKEN
0B9F:0082 PUSH CX
0B9F:0083 PUSH BX
0B9F:0084 CALL 0098 .CONOUT
0B9F:0087 POP BX
ÆTrace through RET instruction to see what value is returned.Å
#t4
AX BX CX DX SP BP SI DI IP
--I-S---C 0F00 0BAA 0000 005C 0377 0000 0100 0100 0069
MOV BX,Æ0108Å .BUFFPTR =0000
--I-S---C 0F00 0000 0000 005C 0377 0000 0100 0100 006D
MOV AL,010AÆBXÅ .BUFF =00
--I-S---C 0F00 0000 0000 005C 0377 0000 0100 0100 0071
INC WORD Æ0108Å .BUFFPTR =0000
--I-----C 0F00 0000 0000 005C 0377 0000 0100 0100 0075
RET
*0B9F:002C
ÆA zero is returned in AL. This is no surprise because the code to read
from the disk file was not executed. BUFFPTR should be initialized to
the size of the buffer, rather than 0. Use the editor to change the
source file.Å
#^C
C>edlin sample.a86
End of input file
*sbuffptr dw
106: buffptr dw 0
*106
106:*buffptr dw 0
106:*buffptr dw 0 buffsize
*e
ÆReassemble and relink.Å
C>rasm86 sample $lo
--------------------------------------------------
RASM-86 Relocating Assembler Version 1.0
Serial No. PPPP-OOOO-SSSSSS All Rights Reserved
Copyright (C) 1982,1983 Digital Research, Inc.
--------------------------------------------------
END OF PASS 1
END OF PASS 2
SEGMENTS
--------
00B4 DATA
00A7 CODE
END OF ASSEMBLY. NUMBER OF ERRORS: 0. USE FACTOR: 1%
C>link86 sample
--------------------------------------------------
LINK-86 Linkage Editor Version 1.0
Serial No. PPPP-OOOO-SSSSSS All Rights Reserved
Copyright (C) 1982,1983 Digital Research, Inc.
--------------------------------------------------
CODE 000AC
DATA 001B4
USE FACTOR: 00%
ÆTry it again.Å
C>sample test.tex
NowqPF1RwqBÆ
æ QR@ÅBUlF91Rwq C
æ#"F1RwqB Q0RH"ÅBUlG"!LH9"wN6"F"sdÅCUl
^7Qcv^C
ÆStill not quite perfect. These "simple" programs are never as easy as
they look! Invoke SID-86 again.Å
C>sid86 sample sample
--------------------------------------------------
SID-86 Symbolic Debugger Version 1.0
Serial No. PPPP-OOOO-SSSSSS All Rights Reserved
Copyright (C) 1983 Digital Research, Inc.
--------------------------------------------------
START END
0B5F:0000 0B5F:09FF
SYMBOLS
#itest.tex
#g,10
*0B9F:0010 .MAIN_LOOP
ÆExecute COLLECT_TOKEN to see what happens.Å
#tw3
AX BX CX DX SP BP SI DI IP
--I--Z-P- 0F00 0BAA 0000 005C 037B 0000 0100 0100 0010
CALL 0029 .COLLECT_TOKEN
--I--Z-P- 1420 0003 0000 005C 037B 0000 0100 0100 0013
CMP BYTE Æ018CÅ,1A .TOKEN =4E
--I------ 1420 0003 0000 005C 037B 0000 0100 0100 0018
JZ 001F .DONE
*0B9F:001A
ÆSee what is in TOKEN.Å
#d.token,+f
0BAA:018C 4E 6F 77 00 00 00 00 00 00 00 00 00 00 00 00 00 Now..........
ÆLooks good this time. Execute the PRINT_TOKEN routine.Å
#tw2
AX BX CX DX SP BP SI DI IP
--I------ 1420 0003 0000 005C 037B 0000 0100 0100 001A
CALL 0076 .PRINT_TOKENNow^C
æ QR@ÅBUlF91Rwq C
æ#"F1RwqB Q0RH"ÅBUlG"!LH9"wN6"F"sdÅCUl
^7Qcv^C
ÆPRINT_TOKEN is not working correctly. Reload the file.Å
#esample sample
START END
0B5F:0000 0B5F:09FF
SYMBOLS
#itest.tex
ÆRun program with breakpoint at PRINT_TOKEN.Å
#g,.print_token
*0B9F:0076 .PRINT_TOKEN
#l
PRINT_TOKEN:
0B9F:0076 MOV CX,Æ018AÅ .TOKEN_LEN
0B9F:007A JCXZ 0097 .PR2
0B9F:007C SUB BX,BX
PR1:
0B9F:007E MOV DL,018CÆBXÅ .TOKEN
0B9F:0082 PUSH CX
0B9F:0083 PUSH BX
0B9F:0084 CALL 0098 .CONOUT
0B9F:0087 POP BX
0B9F:0088 POP CX
0B9F:0089 INC BX
0B9F:008A DEC CX
0B9F:008B LOOP 007E .PR1
#t2
AX BX CX DX SP BP SI DI IP
--I------ 1420 0003 0000 005C 0379 0000 0100 0100 0076
MOV CX,Æ018AÅ .TOKEN_LEN =0003
--I------ 1420 0003 0003 005C 0379 0000 0100 0100 007A
JCXZ 0097 .PR2
*0B9F:007C
ÆTOKEN length of 3 looks good. Trace through end of loop.Å
#tw#10
AX BX CX DX SP BP SI DI IP
--I------ 1420 0003 0003 005C 0379 0000 0100 0100 007C
SUB BX,BX
PR1:
--I--Z-P- 1420 0000 0003 005C 0379 0000 0100 0100 007E
MOV DL,018CÆBXÅ .TOKEN =4E
--I--Z-P- 1420 0000 0003 004E 0379 0000 0100 0100 0082
PUSH CX
--I--Z-P- 1420 0000 0003 004E 0377 0000 0100 0100 0083
PUSH BX
--I--Z-P- 1420 0000 0003 004E 0375 0000 0100 0100 0084
CALL 0098 .CONOUTN
--I--Z-P- 024E 0000 0003 004E 0375 0000 0100 0100 0087
POP BX
--I--Z-P- 024E 0000 0003 004E 0377 0000 0100 0100 0088
POP CX
--I--Z-P- 024E 0000 0003 004E 0379 0000 0100 0100 0089
INC BX
--I------ 024E 0001 0003 004E 0379 0000 0100 0100 008A
DEC CX
--I------ 024E 0001 0002 004E 0379 0000 0100 0100 008B
LOOP 007E .PR1
*0B9F:007E .PR1
ÆThe first character was printed (on the line after ".CONOUT"). Go
through the loop again.Å
#tw9
AX BX CX DX SP BP SI DI IP
--I------ 024E 0001 0001 004E 0379 0000 0100 0100 007E
MOV DL,018CÆBXÅ .TOKEN =6F
--I------ 024E 0001 0001 006F 0379 0000 0100 0100 0082
PUSH CX
--I------ 024E 0001 0001 006F 0377 0000 0100 0100 0083
PUSH BX
--I------ 024E 0001 0001 006F 0375 0000 0100 0100 0084
CALL 0098 .CONOUTo
--I------ 026F 0001 0001 006F 0375 0000 0100 0100 0087
POP BX
--I------ 026F 0001 0001 006F 0377 0000 0100 0100 0088
POP CX
--I------ 026F 0001 0001 006F 0379 0000 0100 0100 0089
INC BX
--I------ 026F 0002 0001 006F 0379 0000 0100 0100 008A
DEC CX
--I--Z-P- 026F 0002 0000 006F 0379 0000 0100 0100 008B
LOOP 007E .PR1
*0B9F:007E .PR1
ÆThe "o" was printed. Do the loop once more.Å
#tw9
AX BX CX DX SP BP SI DI IP
--I--Z-P- 026F 0002 FFFF 006F 0379 0000 0100 0100 007E
MOV DL,018CÆBXÅ .TOKEN =77
--I--Z-P- 026F 0002 FFFF 0077 0379 0000 0100 0100 0082
PUSH CX
--I--Z-P- 026F 0002 FFFF 0077 0377 0000 0100 0100 0083
PUSH BX
--I--Z-P- 026F 0002 FFFF 0077 0375 0000 0100 0100 0084
CALL 0098 .CONOUTw
--I--Z-P- 0277 0002 FFFF 0077 0375 0000 0100 0100 0087
POP BX
--I--Z-P- 0277 0002 FFFF 0077 0377 0000 0100 0100 0088
POP CX
--I--Z-P- 0277 0002 FFFF 0077 0379 0000 0100 0100 0089
INC BX
--I----P- 0277 0003 FFFF 0077 0379 0000 0100 0100 008A
DEC CX
--I-S---- 0277 0003 FFFE 0077 0379 0000 0100 0100 008B
LOOP 007E .PR1
*0B9F:007E .PR1
ÆThe "w" was printed, but now the count in CX should be 0, and it is
FFFE. That is going to loop for a long time. If you look at the code,
CX seems to be decremented by 2 each time through the loop. That "DEC
CX" does not belong there because the LOOP instruction automatically
decremented CX. Reload the program.Å
#esample sample
START END
0B5F:0000 0B5F:09FF
SYMBOLS
ÆList the area containing the extra instruction.Å
#18a,+9
0B9F:008A DEC CX
0B9F:008B LOOP 007E .PR1
0B9F:008D MOV DL,OD .CR
0B9F:008F CALL 0098 .CONOUT
0B9F:0092 MOV DL,0A .LF
ÆUse the Assemble command to overwrite the instruction with a NOP.Å
#a8a
0B9F:008A nop
0B9F:008BØ .
#itest.tex
ÆRun it again.Å
#g
Now
Nowis
Nowisthe
Nowisthetime
Nowisthetimefor
Nowisthetimeforall
Nowisthetimeforallgood
Nowisthetimeforallgoodmen
Nowisthetimeforallgoodmento
Nowisthetimeforallgoodmentocome
Nowisthetimeforallgoodmentocometo
Nowisthetimeforallgoodmentocometothe
Nowisthetimeforallgoodmentocometotheaid
Nowisthetimeforallgoodmentocometotheaidof^C
ÆLooking better, but still not right!Å
C>sid86
--------------------------------------------------
SID-86 Symbolic Debugger Version 1.0
Serial No. PPPP-OOOO-SSSSSS All Rights Reserved
Copyright (C) 1983 Digital Research, Inc.
--------------------------------------------------
ÆThis time patch the program to avoid the edit, assemble, and link loop.
Use the Read command to bring in the file with its header.Å
#rsample.exe
START END
OB4F:0000 0B4F:09FF
ÆList the area to patch (add 60H paragraphs to where the file was loaded
to get past the header).Å
#lb4f+60:8a
0BAF:008A DEC CX
0BAF:008B LOOP 007E
0BAF:008D MOV DL,0D
0BAF:008F CALL 0098
0BAF:0092 MOV DL,0A
0BAF:0094 CALL 0098
0BAF:0097 RET
0BAF:0098 MOV AH,02
0BAF:009A INT 21
0BAF:009C RET
0BAF:009D MOV AH,09
0BAF:009F INT 21
ÆAssemble the NOP instruction.Å
#a8a
0BAF:008A nop
0BAF:008BØ .
ÆWrite the file back to disk (no start and end addresses are needed
since the length of the file did not change).Å
#wsample.exe
ÆReload the patched file and the symbols.Å
#esample sample
START END
0B5F:0000 0B5F:09FF
SYMBOLS
#itest.tex
ÆSet a pass point of MAIN_LOOP with a count of 2 because the first token
came out correct.Å
#p.main_loop,2
ÆStart program. Execution stops when pass count reaches 1.Å
#g
0002 PASS 0B9F:0010 .MAIN_LOOP
--I--Z-P- 0F00 0BAA 0000 005C 037B 0000 0100 0100 0010
CALL 0029 .COLLECT_TOKENNow
0001 PASS 0B9F:0010 .MAIN_LOOP
--I----P- 020A 0003 0000 000A 037B 0000 0100 0100 0010
CALL 0029 .COLLECT_TOKEN
*0B9F:0029 .COLLECT_TOKEN
#1
COLLECT_TOKEN:
0B9F:0029 CALL 004F .GET_CHAR
0B9F:002C CALL 0040 .CHECK_DELIM
0B9F:002F JZ 0031 .COLI
0B9F:0031 MOV BX,Æ018AÅ .TOKEN_LEN
0B9F:0035 MOV 018CÆBXÅ,AL .TOKEN
0B9F:0039 INC WORD Æ018AÅ .TOKEN_LEN
0B9F:003D JMPS 0029 .COLLECT_TOKEN
COL1:
0B9F:003F RET
CHECK_DELIM:
0B9F:0040 CMP AL,0D .CR
0B9F:0042 JZ 004E .CRET
0B9F:0044 CMP AL,0A .LF
0B9F:0046 JZ 004E .CRET
ÆTrace without call to see what GET_CHAR and CHECK_DELIM return.Å
#tw3
AX BX CX DX SP BP SI DI IP
--I----P- 020A 0003 0000 000A 0379 0000 0100 0100 0029
CALL 004F .GET_CHAR
--I----PC 0269 0004 0000 000A 0379 0000 0100 0100 002C
CALL 0040 .CHECK_DELIM
--I------ 0269 0004 0000 000A 0379 0000 0100 0100 002F
JZ 003F .COL1
*0B9F:0031
ÆGET_CHAR returns a 69H. To translate to ASCII, use the M command.Å
#h69
0069 #105 'i' .GET1
ÆThat looks good. See what happens next.Å
#1
0B9F:0031 MOV BX,Æ018AÅ .TOKEN_LEN
0B9F:0035 MOV 018CÆBXÅ,AL .TOKEN
0B9F:0039 INC WORD Æ018AÅ .TOKEN_LEN
0B9F:003D JMPS 0029 .COLLECT_TOKEN
COL1:
0B9F:003F RET
CHECK_DELIM:
0B9F:0040 CMP AL,OD .CR
0B9F:0042 JZ 004E .CRET
0B9F:0044 CMP AL,OA .LF
0B9F:0046 JZ 004E .CRET
0B9F:0048 CMP AL,09 .TAB
0B9F:004A JZ 004E .CRET
0B9F:004C CMP AL,20 .ERR
ÆTrace the code that puts the character into the TOKEN buffer.Å
#tw4
AX BX CX DX SP BP SI DI IP
--I------ 0269 0004 0000 000A 0379 0000 0100 0100 0031
MOV BX,Æ018AÅ .TOKEN_LEN =0003
--I------ 0269 0003 0000 000A 0379 0000 0100 0100 0035
MOV 018CÆBXÅ,AL .TOKEN =00
--I------ 0269 0003 0000 000A 0379 0000 0100 0100 0039
INC WORD Æ018AÅ .TOKEN_LEN =0003
--I------ 0269 0003 0000 000A 0379 0000 0100 0100 003D
JMPS 0029 .COLLECT_TOKEN
*0B9F:0029 .COLLECT_TOKEN
ÆAha! TOKEN_LEN is 3, instead of 0. It seems that TOKEN_LEN is not
getting reset for each new token. Try changing TOKEN_LEN on the fly to
see if our theory is correct.Å
START END
0B5F:0000 0B5F:09FF
SYMBOLS
#itest.tex
#p.main_loop,2
#g
0002 PASS 0B9F:0010 .MAIN_LOOP
--I--Z-P- 0F00 0BAA 0000 005C 037B 0000 0100 0100 0010
CALL 0029 .COLLECT_TOKENow
0001 PASS 0B9F:0010 .MAIN_LOOP
--I----P- 020A 0003 0000 000A 037B 0000 0100 0100 0010
CALL 0029 .COLLECT_TOKEN
ÆChange the value of TOKEN_LEN to 0.Å
#sw.token_len
0BAA:018A 0003 0
0BAA:018C 6F4EØ .
ÆPress next token (pass point still set at MAIN_LOOP).Å
#g
is
0001 PASS 0B9F:0010 .MAIN_LOOP
--I------ 020A 0002 0000 000A 037B 0000 0100 0010
CALL 0029 .COLLECT_TOKEN
*0B9F:0029 .COLLECT_TOKEN
ÆIt printed "is" correctly. That must be the problem. Put in both
changes at the source level, reassemble, and relink.Å
#^C
C>edlin sample.a86
End of input file
*sdec cx
75: dec cx
*75d
*1,20sloop:
17: main_loop:
*18i
18:* mov token_len,0
19:*^Z
*e
C>rasm86 sample $1o
--------------------------------------------------
RASM-86 Relocating Assembler Version 1.0
Serial No. PPPP-OOOO-SSSSSS All Rights reserved
Copyright (C) 1982,1983 Digital Research, Inc.
--------------------------------------------------
END OF PASS 1
END OF PASS 2
SEGMENTS
________
00B4 DATA
00AC CODE
END OF ASSEMBLY. NUMBER OF ERRORS: 0. USE FACTOR: 1%
C>link86 sample
--------------------------------------------------
LINK-86 Linkage Editor Version 1.0
Serial No. PPPP-OOOO-SSSSSS All Rights Reserved
Copyright (C) 1982,1983 Digital Research, Inc.
--------------------------------------------------
CODE 000B1
DATA 001B4
USE FACTOR: 00%
ÆOne last try!Å
C>sample test.tex
Now
is
the
time
for
all
good
men
to
come
to
the
aid
of
their
country.
ÆFinally! Just out of curiosity, use the pass point feature to count
the number of tokens in the file.Å
C>sid86 sample sample
--------------------------------------------------
SID-86 Symbolic Debugger Version 1.0
Serial No. PPPP-OOOO-SSSSSS All Rights Reserved
Copyright (C) 1983 Digital Research, Inc.
--------------------------------------------------
START END
0B5F:0000 0B5F:09FF
SYMBOLS
#itest.tex
ÆSet pass count of FFFF, so SID-86 counts each time MAIN_LOOP is
executed.Å
#p.main_loop,ffff
ÆExecute program, suppressing pass point display.Å
#-g
Now
is
the
time
for
all
good
men
to
come
to
the
aid
of
their
country.
PROGRAM TERMINATED NORMALLY
ÆDisplay the pass point and its current pass count.Å
#p
FFED 0B9F:0010 .MAIN_LOOP
ÆSubtract from FFFF to calculate number of times MAIN_LOOP was
executed.Å
#hffff-ffed
0012 #18
ÆThere are 18 tokens in the file.Å
#^C
ÆList the final version of the program.Å
C>type sample.a86
;
; This program reads an ASCII file, breaking it up into "tokens",
; which are displayed on the console.
;
fcb equ 5ch
cr equ 0dh
lf equ 0ah
tab equ 09h
end_file equ 1ah
init:
mov dx,fcb
mov ah,15
int 21h
or al,al
jnz err
main_loop:
mov token_len,0
call collect_token
cmp token,end_file
jz done
call print_token
jmps main_loop
done:
retf
err: mov dx,offset nofile
call printm
jmp done
collect_token:
call get_char
call check_delim
jz coli
mov bx,token_len
mov tokenÆbxÅ,al
inc token_len
jmps collect_token
coli: ret
check_delim:
cmp al,cr
jz cret
cmp al,lf
jz creet
cmp al,tab
jz cret
cmp al,' '
cret: ret
get_char:
cmp buffptr, buffsize
jc get1
mov dx,offset buff
call setdta
mov dx,fcb
call readsec
mov buffptr,0
get1:
mov bx,buffptr
mov al,buffÆbxÅ
inc buffptr
ret
print_token:
mov cx,token_len
jcxz pr2
sub bx,bx
pr1: mov dl,tokenÆbxÅ
push cx
push bx
call conout
pop bx
pop cx
inc bx
loop pr1
mov dl,cr
call conout
mov dl,lf
call conout
pr2:
ret
conout: mov ah,2
int 21h
ret
printm: mov ah,9
int 21h
ret
readsec:
mov ah,20
int 21h
ret
setdta: mov ah,26
int 21h
ret
dseg
nofile db 'NO FILE$'
buffsize equ 128
buffptr dw buffsize
buff rb buffsize
max_token equ 40
token_len rw 1
token rb max_token
end
«eof»