 Trying To Program In Assembly And Keep Getting Error |
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  Nov 15 2006, 05:47 AM
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#1
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Newbie  Group: Members Posts: 5 Joined: 15-November 06 Member No.: 33,396  |
I am brand new at learning Assembly...and can't seem to get this proram to execute....
This is my code.... CODE ;;;;;%include "NASMENV\lib\io.mac" .STACK 100H .DATA char_prompt db "Please input a character: ",0 out_msg1 db "The ASCII code of ' ",0 out_msg2 db "' in hex is ",0 query_msg db "Do you want to quit (Y/N): ",0 ; translation table: 4-bit binary to hex hex-table db "012345789ABCDEF", 0 .CODE .STARTUP read_char: PutStr char_prompt; request a char. input GetCh AL PutStr out_msg1 PutCh AL PutStr out_msg2 mov AH,AL ; save input character in AH mov EBX, hex_table; EBX = translation table shr AL,4 ; move upper 4 bits to lower half xlatb ; replace AL with hex digit PutCh AL ; write the first hex digit mov AL,AH ; restore input character to AL and AL,0FH ; mask off upper 4 bits xlatb PutCh AL ; write the second hex digit nwln PutStr query_msg; query user whether to terminate GetCh AL ; read response cmp AL, 'Y' ; if response is not 'Y' jne read_char; read another character done: .EXIT When I attempt to make...I get the below.... PLEASE HELP! This is driving me bonkers! QUOTE J:\NASMENV\ASM\Hex2Char>make
MAKE Version 5.2 Copyright © 1987, 2000 Borland /NASMENV/NASM/nasm-0.98.39/nasm -o hex2char.obj -f obj -l hex2char.lst - P /NASMENV/lib/io.mac hex2char.asm J:\NASMENV\lib\io.mac:7: warning: redefining multi-line macro `.STACK' J:\NASMENV\lib\io.mac:15: warning: redefining multi-line macro `.DATA' J:\NASMENV\lib\io.mac:21: warning: redefining multi-line macro `.UDATA' J:\NASMENV\lib\io.mac:27: warning: redefining multi-line macro `.CODE' J:\NASMENV\lib\io.mac:35: warning: redefining multi-line macro `.STARTUP' J:\NASMENV\lib\io.mac:49: warning: redefining multi-line macro `.EXIT' J:\NASMENV\lib\io.mac:57: warning: redefining multi-line macro `nwln' J:\NASMENV\lib\io.mac:64: warning: redefining multi-line macro `PutCh' J:\NASMENV\lib\io.mac:74: warning: redefining multi-line macro `PutStr' J:\NASMENV\lib\io.mac:84: warning: redefining multi-line macro `GetStr' J:\NASMENV\lib\io.mac:99: warning: redefining multi-line macro `GetCh' J:\NASMENV\lib\io.mac:120: warning: redefining multi-line macro `PutInt' J:\NASMENV\lib\io.mac:130: warning: redefining multi-line macro `GetInt' J:\NASMENV\lib\io.mac:143: warning: redefining multi-line macro `PutLInt' J:\NASMENV\lib\io.mac:152: warning: redefining multi-line macro `GetLInt' hex2char.asm:18: error: parser: instruction expected ** error 1 ** deleting hex2char.obj |
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Nov 16 2006, 01:27 AM
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#2
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Super Member Group: Members Posts: 397 Joined: 9-June 06 From: Wisconsin Member No.: 24,924 |
QUOTE hex-table db "012345789ABCDEF", 0 EBX is a 32-bit variable. This means it can hold a total of 32 bits / 8 bits per byte or a total of 4 bytes. The value you are trying to put in there is 17 bytes. Perhaps you are supposed to be putting the location of hex_table in EBX? I'm not familiar with some of the instructions you are using so I couldn't tell you. Post back and I can try and help you out more. I've been using assembly for 3 years. |
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Nov 16 2006, 11:53 PM
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#3
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Newbie Group: Members Posts: 5 Joined: 15-November 06 Member No.: 33,396 |
Hi Ghostrider!
 Thanks soooooo much for responding. I can't imagine anyone who would take this course because they want to. I am currently enrolled in the course because I have toooo...a tutor...I definitely need... anyway... I believe I am moving the hex_table into EBX...see a copy of the code below.... Any and all help is greatly appreciated...Thanks...mov EBX, hex_table; EBX = translation table QUOTE(Angela @ Nov 14 2006, 11:47 PM)  I am brand new at learning Assembly...and can't seem to get this proram to execute.... This is my code.... CODE ;;;;;%include "NASMENV\lib\io.mac" .STACK 100H .DATA char_prompt db "Please input a character: ",0 out_msg1 db "The ASCII code of ' ",0 out_msg2 db "' in hex is ",0 query_msg db "Do you want to quit (Y/N): ",0 ; translation table: 4-bit binary to hex hex-table db "012345789ABCDEF", 0 .CODE .STARTUP read_char: PutStr char_prompt; request a char. input GetCh AL PutStr out_msg1 PutCh AL PutStr out_msg2 mov AH,AL; save input character in AH mov EBX, hex_table; EBX = translation table shr AL,4; move upper 4 bits to lower half xlatb ; replace AL with hex digit PutCh AL; write the first hex digit mov AL,AH; restore input character to AL and AL,0FH; mask off upper 4 bits xlatb PutCh AL; write the second hex digit nwln PutStr query_msg; query user whether to terminate GetCh AL; read response cmp AL, 'Y'; if response is not 'Y' jne read_char; read another character done: .EXIT When I attempt to make...I get the below.... PLEASE HELP! This is driving me bonkers! |
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Nov 17 2006, 01:30 AM
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#4
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Super Member Group: Members Posts: 397 Joined: 9-June 06 From: Wisconsin Member No.: 24,924 |
I'm sorry I can't elorborate on this more, but I found this on the internet. It explains the xlatb function. You need to put the address of the table in EBX, not the table itself.
CODE lea EBX, hex-table ;lea stands for load effective address. Here is what I found on the internet: QUOTE Description Locates a byte entry in a table in memory, using the contents of the AL register as a table index, then copies the contents of the table entry back into the AL register. The index in the AL register is treated as an unsigned integer. The XLAT and XLATB instructions get the base address of the table in memory from either the DS:EBX or the DS:BX registers (depending on the address-size attribute of the instruction, 32 or 16, respectively). (The DS segment may be overridden with a segment override prefix.) At the assembly-code level, two forms of this instruction are allowed: the "explicit-operand" form and the "no-operand" form. The explicit-operand form (specified with the XLAT mnemonic) allows the base address of the table to be specified explicitly with a symbol. This explicit-operands form is provided to allow documentation; however, note that the documentation provided by this form can be misleading. That is, the symbol does not have to specify the correct base address. The base address is always specified by the DS:(E)BX registers, which must be loaded correctly before the XLAT instruction is executed. The no-operands form (XLATB) provides a "short form" of the XLAT instructions. Here also the processor assumes that the DS:(E)BX registers contain the base address of the table. Hope this helps. |
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Nov 17 2006, 07:28 PM
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#5
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Newbie Group: Members Posts: 5 Joined: 15-November 06 Member No.: 33,396 |
Hi Ghostrider! Any help is elaboration is better than none...I will try this..and I'll let you know how it turns out. Thanks again soooo much for your time and Assembly knowledge. It's much appreciated.
Angela QUOTE(ghostrider @ Nov 16 2006, 07:30 PM) I'm sorry I can't elorborate on this more, but I found this on the internet. It explains the xlatb function. You need to put the address of the table in EBX, not the table itself. CODE lea EBX, hex-table ;lea stands for load effective address. Here is what I found on the internet: Hope this helps. |
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Nov 18 2006, 03:35 AM
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#6
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Super Member Group: Members Posts: 397 Joined: 9-June 06 From: Wisconsin Member No.: 24,924 |
I'm glad I was able to help you out. I know Assembly starts out boring and not fun, but ever since I learned it I have noticed that I prorgam more creatively, and problem solving is much easier. Both of those skills are great to have. Also, why do you have 5 semicolons in front of your include statement?
CODE ;;;;;%include "NASMENV\lib\io.mac" |
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Nov 20 2006, 11:11 AM
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#7
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Newbie Group: Members Posts: 5 Joined: 15-November 06 Member No.: 33,396 |
Hi Ghostrider! Well I figured it out.
in my code... I used hex-table db "0123456789ABCDEF" instead hex_table db "0123456789ABCDEF". I used a hyphen instead of the underscore. That made the difference. In regard to the semi colons on my include statement.....that was intentional. I also removed the semi colons and my program ran. Thanks for getting my juices to flowing. I hope that your available in the future...because I am sure that I will have more assembly questions. Angela QUOTE(ghostrider @ Nov 17 2006, 09:35 PM) I'm glad I was able to help you out. I know Assembly starts out boring and not fun, but ever since I learned it I have noticed that I prorgam more creatively, and problem solving is much easier. Both of those skills are great to have. Also, why do you have 5 semicolons in front of your include statement? CODE ;;;;;%include "NASMENV\lib\io.mac" |
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