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Hey guys,
I'm having a problem with a variable within a function. This variable is set to zero at the begging of the block, and used as an index for a few arrays. The ONLY place where it is changed is in the for(...; ...; Channel++) portion of the loop. Somehow this number is being set to -1. The range for this int 0 - 7. Any clues what could be happening?
I win because I have the most fun in life...
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any chance to see a relevant piece of code ?
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<br />
int Channel; <br />
for( Channel = 0; Channel < NumberOfChannels; Channel++ )<br />
{<br />
Dat = (unsigned char*)m_Dither.Dat[Channel];<br />
Out = (unsigned char*)lpDithered->Data[Channel]; <br />
ChannelData = &(lpDthrCtrl->Data[Channel]);<br />
<br />
memset(Out,0x00,OutLen);<br />
<br />
there is a lot more going on under this portion, but this is the only place that Channel is used.
I win because I have the most fun in life...
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you say it then equals -1.
where have you tested this value.
have you tried to set breakpoints and use your debugger to find out exactly where the change occurs ?
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Im using VS2005, and i test the value using break points and checking the locals portion of the debugger. i do a conditional break at the beginning of the block if (Channel = -1). I also break at the the two function calls within this block. None of these functions take Channel as an argument. I also break at the end of the block to check Channel. Now it is impossible to check the value at each break all the time, because this function is called roughly a million times(deals with individual pixels split into various ink channels for images ~150+ Mb).
I win because I have the most fun in life...
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VonHagNDaz wrote: if (Channel = -1).
  !!!
man, it should be this :
if (Channel <code>==</code> -1)
by using = instead of ==, you're assigning it !
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typo, but thats the statement for the conditional breakpoint, its not in the code. I just found out about those today, i like em
I win because I have the most fun in life...
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toxcct wrote: man, it should be this :
if (Channel == -1)
by using = instead of ==, you're assigning it !
Does the debugger differentiate between == (compare) and = (assign)?
"Approved Workmen Are Not Ashamed" - 2 Timothy 2:15
"Judge not by the eye but by the heart." - Native American Proverb
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since this is a conditional break, no assignments are made. this is a feature within the vs2005 debugger. im not sure of all the ins and outs because i just found out about it today
I win because I have the most fun in life...
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VonHagNDaz wrote: this is a feature within the vs2005 debugger.
I suspected such, hence my question to toxcct for clarification.
"Approved Workmen Are Not Ashamed" - 2 Timothy 2:15
"Judge not by the eye but by the heart." - Native American Proverb
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Actually, it should be written thus:
if (-1 == Channel)
so if you mistakenly use = instead of == the compiler will puke.
If you get in the habit of putting the constant on the left side of the equation it'll save you many headaches.
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yeah, i know this, but I don't like it ! lol
but for beginners, (for which the chance to fall in the trap is approaching the 100%), they should take this habbit...
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VonHagNDaz wrote: for( Channel = 0; Channel < NumberOfChannels; Channel++ )
What is NumberOfChannels? What is its value?
Would it be possible to comment out everything in the for loop?
VonHagNDaz wrote: memset(Out,0x00,OutLen);
What is Out? What is the value of OutLen?
"Approved Workmen Are Not Ashamed" - 2 Timothy 2:15
"Judge not by the eye but by the heart." - Native American Proverb
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number of channels represents the differnt ink cartridges inside of the E*s*n printers we are modifying. 1 - 8 for dual CMYK printing.
I cant comment these out because they access the arrays(one for each channel) which the pixel information for each ink channel is stored.
Out is the pixel data for that channel, and OutLen is the length of the data that is expected. say 16 pixel wide image, four ink channels, you would end up with four arrays each containing the color data for that specific channel for each pixel.
I win because I have the most fun in life...
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VonHagNDaz wrote: number of channels represents the differnt ink cartridges inside of the E*s*n printers we are modifying. 1 - 8 for dual CMYK printing...Out is the pixel data for that channel, and OutLen is the length of the data that is expected. say 16 pixel wide image, four ink channels, you would end up with four arrays each containing the color data for that specific channel for each pixel.
That's all well and good, but it did nothing to answer my questions. When I asked about NumberOfChannels, is it an int, short, char, etc? What value does it have (not what it should have) at the start of the for loop?
"Approved Workmen Are Not Ashamed" - 2 Timothy 2:15
"Judge not by the eye but by the heart." - Native American Proverb
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sorry about that, Channel is an int and is set to zero at the start of the loop, out is an unsigned char*, and Outlen is and unsigned int.
I win because I have the most fun in life...
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VonHagNDaz wrote: Channel is an int and is set to zero at the start of the loop,
That's obvious from your code snippet. I was asking about NumberOfChannels.
VonHagNDaz wrote: ...out is an unsigned char*...
But what is its size? If it has not been initialized, memset() should fail if OutLen is anything other than 0 or 1.
VonHagNDaz wrote: Outlen is and unsigned int.
But what is its value at the time of memset()?
"Approved Workmen Are Not Ashamed" - 2 Timothy 2:15
"Judge not by the eye but by the heart." - Native American Proverb
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man, im sorry i keep making you ask me twice, i dont know where my head is at this morning.
NumberOfChannels is an int. both NumberOfChannels and Outlen are set outside by the calling class, and not altered with in this class.
I win because I have the most fun in life...
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VonHagNDaz wrote: NumberOfChannels is an int.
Ok, but you still have not indicated their respective values prior to being used. Can you not just set a breakpoint on the for and memset() statements and look at their values in the watch window?
"Approved Workmen Are Not Ashamed" - 2 Timothy 2:15
"Judge not by the eye but by the heart." - Native American Proverb
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there values are NumberOfChannels 4 and OutLen 2692. its just randomly that Channel = -1. Sometimes everything works out and Channel never goes to -1, and it never goes to -1 at the same iteration through the loop. It crashes either randomly, or not at all.
I win because I have the most fun in life...
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VonHagNDaz wrote: ...and OutLen 2692.
So does Out have enough room for 2692 characters?
VonHagNDaz wrote: its just randomly that Channel = -1.
Computers never do anything at random. They do exactly what they were instructed to do.
"Approved Workmen Are Not Ashamed" - 2 Timothy 2:15
"Judge not by the eye but by the heart." - Native American Proverb
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DavidCrow wrote: They do exactly what they were instructed to do
You have to use the good ole fashion "tool blame" to keep a small amount of sanity.
Yes, it is being allocated the proper space. A coworker has suggested that it might be a memory error where something is writing to that chunk and skewing the number?
I win because I have the most fun in life...
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VonHagNDaz wrote: A coworker has suggested that it might be a memory error where something is writing to that chunk and skewing the number?
That's what I've been tring to get at for several posts now, but without having any actual numbers, could not be for sure.
"Approved Workmen Are Not Ashamed" - 2 Timothy 2:15
"Judge not by the eye but by the heart." - Native American Proverb
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is there some slick way to see whats going on? ive tried watching that address with the memory view part of the debugger, but it doesnt show where anything is writing to that address.
I win because I have the most fun in life...
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Set a breakpoint on any of the statements within the for loop. Add Channel to the watch window. Go through the for loop using F5. Watch Channel at each iteration. Hopefully you'll see it change to -1.
"Approved Workmen Are Not Ashamed" - 2 Timothy 2:15
"Judge not by the eye but by the heart." - Native American Proverb
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