Programming Forums > Application Development > Assembly

saxman · Dec 16th, 2004, 12:50 PM

I'm calling the FREAD function in assembly, but I have an issue. This is what I'm trying to accomplish:

unsigned short int * *value1;
unsigned short int * *value2;
unsigned short int * *value3;
unsigned short int * *value4;
FILE * **GSShandle

// ~~ cut out some code to show you what I'm looking at ~~ //

fread(&value1, sizeof(short int), 1, GSShandle);
fread(&value2, sizeof(short int), 1, GSShandle);
fread(&value3, sizeof(short int), 1, GSShandle);
fread(&value4, sizeof(short int), 1, GSShandle);

As you can see, the valueX variables are defined one after another. In theory, I would believe that I could use a single FREAD and write to all 4. This is what I put into ASM:

(Toggle Plain Text)

push * *ebx * * * * * *;I had put GSShandle here prior to this code
push * *4 * * * * * * *;4 values
push * *2 * * * * * * *;Define each value as 'WORD' size
push * *offset value1 *;Set the offset to 'VALUE1'
call * *fseek * * * * *;Do it's thing
add * * esp, 10h * * *;Fix our stack

When I try it, the results are not what I thought they would be. I am having a pretty difficult time debugging this and seeing what it's 'actually' doing. I was wondering if anyone had any clue as to why my ASM code doesn't work. I realize I could do each of the 4 FREAD's, but I thought it'd be neat to do all 4 in 1 shot.

EDIT: Perhaps this belongs in the C forum instead of this one. I guess I put it here since I was experimenting with the function in assembly... would it be too much trouble if this was moved to C? I think my chances of getting a reply would increase!

SubhadeepGhosh · Jan 4th, 2005, 3:44 AM

Hey,
The first thing I would like to point out is....instead of using offset use lea...offset is a compile time directive....while lea is a runtime directive...try that and let me know....

Dec 16th, 2004, 12:50 PM	#1
saxman Newbie Join Date: Dec 2004 Posts: 7 Rep Power: 0	I'm calling the FREAD function in assembly, but I have an issue. This is what I'm trying to accomplish: (Toggle Plain Text) unsigned short int * value1; unsigned short int value2; unsigned short int value3; unsigned short int value4; FILE *GSShandle // ~~ cut out some code to show you what I'm looking at ~~ // fread(&value1, sizeof(short int), 1, GSShandle); fread(&value2, sizeof(short int), 1, GSShandle); fread(&value3, sizeof(short int), 1, GSShandle); fread(&value4, sizeof(short int), 1, GSShandle); unsigned short int value1; unsigned short int value2; unsigned short int value3; unsigned short int value4; FILE *GSShandle // ~~ cut out some code to show you what I'm looking at ~~ // fread(&value1, sizeof(short int), 1, GSShandle); fread(&value2, sizeof(short int), 1, GSShandle); fread(&value3, sizeof(short int), 1, GSShandle); fread(&value4, sizeof(short int), 1, GSShandle); As you can see, the valueX variables are defined one after another. In theory, I would believe that I could use a single FREAD and write to all 4. This is what I put into ASM: (Toggle Plain Text) push ebx * * * * ;I had put GSShandle here prior to this code push 4 * * * * * ;4 values push 2 * * * * * ;Define each value as 'WORD' size push offset value1 ;Set the offset to 'VALUE1' call * fseek * * * ;Do it's thing add * esp, 10h * * ;Fix our stack push ebx * * * * ;I had put GSShandle here prior to this code push 4 * * * * * ;4 values push 2 * * * * * ;Define each value as 'WORD' size push offset value1 ;Set the offset to 'VALUE1' call * fseek * * * ;Do it's thing add * esp, 10h * * *;Fix our stack When I try it, the results are not what I thought they would be. I am having a pretty difficult time debugging this and seeing what it's 'actually' doing. I was wondering if anyone had any clue as to why my ASM code doesn't work. I realize I could do each of the 4 FREAD's, but I thought it'd be neat to do all 4 in 1 shot. EDIT: Perhaps this belongs in the C forum instead of this one. I guess I put it here since I was experimenting with the function in assembly... would it be too much trouble if this was moved to C? I think my chances of getting a reply would increase!

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Jan 4th, 2005, 3:44 AM	#2
SubhadeepGhosh Newbie Join Date: Jan 2005 Posts: 4 Rep Power: 0	Hey, The first thing I would like to point out is....instead of using offset use lea...offset is a compile time directive....while lea is a runtime directive...try that and let me know....

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Programming Forums > Application Development > Assembly

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