Any Idea why? ....
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I've created an array of unsigned chars as a parity table. During program initialization, I originally memset the array to all zeros. In the same init sequence, I set elements of the array to one to signify that the parity bit should be set for that particular value. // in header file #define RADAR_PARITYTBLSZ 4096 unsigned char RadarParityTable[RADAR_PARITYTBLSZ]; // in .C file // Initialize parity table for 12 bit radar msgs and 1 bit of parity memset(&RadarParityTable, 0, sizeof(RadarParityTable)); for(i = 0; i < RADAR_PARITYTBLSZ; i++) if(ComputeParity(i) == 0) // this returns 0 if value of i is even RadarParityTable[i] = 1; The problem is that the last element of the array, in this case [4095], (the array is 4096 bytes in size, is mysteriously set to 0x20 instead of 1. I'm using odd parity so the parity for a value of 0xfff or 4095 -- 12 binary bits set means add one to it to make it odd. I set a breakpoint right after the code above in the init sequence and Quickwatch says ALL of the values are zero. Later when I compare parity to the parity table in another module and use quickwatch, the value for that element is 0x20. The only way I was able to fix this was to increase the size of the array by 1 to 4097, initialize the first 4096 elements the same as before, and then all of the values in the array were correct even the last one. I even tried adding this line of code below in the init sequence but it didn't work. RadarParityTable[RADAR_PARITYTBLSZ-1] = 1; Any ideas why it was set to hex 0x20.
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I've created an array of unsigned chars as a parity table. During program initialization, I originally memset the array to all zeros. In the same init sequence, I set elements of the array to one to signify that the parity bit should be set for that particular value. // in header file #define RADAR_PARITYTBLSZ 4096 unsigned char RadarParityTable[RADAR_PARITYTBLSZ]; // in .C file // Initialize parity table for 12 bit radar msgs and 1 bit of parity memset(&RadarParityTable, 0, sizeof(RadarParityTable)); for(i = 0; i < RADAR_PARITYTBLSZ; i++) if(ComputeParity(i) == 0) // this returns 0 if value of i is even RadarParityTable[i] = 1; The problem is that the last element of the array, in this case [4095], (the array is 4096 bytes in size, is mysteriously set to 0x20 instead of 1. I'm using odd parity so the parity for a value of 0xfff or 4095 -- 12 binary bits set means add one to it to make it odd. I set a breakpoint right after the code above in the init sequence and Quickwatch says ALL of the values are zero. Later when I compare parity to the parity table in another module and use quickwatch, the value for that element is 0x20. The only way I was able to fix this was to increase the size of the array by 1 to 4097, initialize the first 4096 elements the same as before, and then all of the values in the array were correct even the last one. I even tried adding this line of code below in the init sequence but it didn't work. RadarParityTable[RADAR_PARITYTBLSZ-1] = 1; Any ideas why it was set to hex 0x20.
Nothing in the code that you show should have this result. Why not use a data breakpoint in the debugger to see when the element is being overwritten? Data breakpoints are set with Edit / BreakPoints and then selecting the Data tab. Enter as the expression: RadarParityTable[4095] Best regards, John
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I've created an array of unsigned chars as a parity table. During program initialization, I originally memset the array to all zeros. In the same init sequence, I set elements of the array to one to signify that the parity bit should be set for that particular value. // in header file #define RADAR_PARITYTBLSZ 4096 unsigned char RadarParityTable[RADAR_PARITYTBLSZ]; // in .C file // Initialize parity table for 12 bit radar msgs and 1 bit of parity memset(&RadarParityTable, 0, sizeof(RadarParityTable)); for(i = 0; i < RADAR_PARITYTBLSZ; i++) if(ComputeParity(i) == 0) // this returns 0 if value of i is even RadarParityTable[i] = 1; The problem is that the last element of the array, in this case [4095], (the array is 4096 bytes in size, is mysteriously set to 0x20 instead of 1. I'm using odd parity so the parity for a value of 0xfff or 4095 -- 12 binary bits set means add one to it to make it odd. I set a breakpoint right after the code above in the init sequence and Quickwatch says ALL of the values are zero. Later when I compare parity to the parity table in another module and use quickwatch, the value for that element is 0x20. The only way I was able to fix this was to increase the size of the array by 1 to 4097, initialize the first 4096 elements the same as before, and then all of the values in the array were correct even the last one. I even tried adding this line of code below in the init sequence but it didn't work. RadarParityTable[RADAR_PARITYTBLSZ-1] = 1; Any ideas why it was set to hex 0x20.
You probably have another array on the atck which is writing beyond its bounds. Take a look at the other vars declared next to your array. Roger Allen Sonork 100.10016 If I had a quote, it would be a very good one.
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Nothing in the code that you show should have this result. Why not use a data breakpoint in the debugger to see when the element is being overwritten? Data breakpoints are set with Edit / BreakPoints and then selecting the Data tab. Enter as the expression: RadarParityTable[4095] Best regards, John
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I've created an array of unsigned chars as a parity table. During program initialization, I originally memset the array to all zeros. In the same init sequence, I set elements of the array to one to signify that the parity bit should be set for that particular value. // in header file #define RADAR_PARITYTBLSZ 4096 unsigned char RadarParityTable[RADAR_PARITYTBLSZ]; // in .C file // Initialize parity table for 12 bit radar msgs and 1 bit of parity memset(&RadarParityTable, 0, sizeof(RadarParityTable)); for(i = 0; i < RADAR_PARITYTBLSZ; i++) if(ComputeParity(i) == 0) // this returns 0 if value of i is even RadarParityTable[i] = 1; The problem is that the last element of the array, in this case [4095], (the array is 4096 bytes in size, is mysteriously set to 0x20 instead of 1. I'm using odd parity so the parity for a value of 0xfff or 4095 -- 12 binary bits set means add one to it to make it odd. I set a breakpoint right after the code above in the init sequence and Quickwatch says ALL of the values are zero. Later when I compare parity to the parity table in another module and use quickwatch, the value for that element is 0x20. The only way I was able to fix this was to increase the size of the array by 1 to 4097, initialize the first 4096 elements the same as before, and then all of the values in the array were correct even the last one. I even tried adding this line of code below in the init sequence but it didn't work. RadarParityTable[RADAR_PARITYTBLSZ-1] = 1; Any ideas why it was set to hex 0x20.
JohnnyG wrote: memset(&RadarParityTable, 0, sizeof(RadarParityTable)); to memset(RadarParityTable, 0, sizeof(RadarParityTable)); Did you corrected this ??? Hth....;) Ramu
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You probably have another array on the atck which is writing beyond its bounds. Take a look at the other vars declared next to your array. Roger Allen Sonork 100.10016 If I had a quote, it would be a very good one.
You were right and John Barton's suggestion helped me identify the problem though I still have to find out why. Apparently, that element in the array gets overwritten when I'm using strtok() on some other data. I'm not sure if it's because I'm using strtok in a thread or if I'm doing some bad pointer arithmetic. I use strtok on a buffer and then later do... *(p - 1) = ' '; because I need to place spaces back into the buffer so that I can look for two spaces. It could be that statement. Anyways, thanks for the help, guys.
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You were right and John Barton's suggestion helped me identify the problem though I still have to find out why. Apparently, that element in the array gets overwritten when I'm using strtok() on some other data. I'm not sure if it's because I'm using strtok in a thread or if I'm doing some bad pointer arithmetic. I use strtok on a buffer and then later do... *(p - 1) = ' '; because I need to place spaces back into the buffer so that I can look for two spaces. It could be that statement. Anyways, thanks for the help, guys.
*(p - 1) = ' '; will put a space character in the byte imedieatly preceeding the location pointed to by p. If p is a pointer to the location after your buffer, the last character of your buffer will become a 0x20 (space character).
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JohnnyG wrote: memset(&RadarParityTable, 0, sizeof(RadarParityTable)); to memset(RadarParityTable, 0, sizeof(RadarParityTable)); Did you corrected this ??? Hth....;) Ramu
Sorry, I didn't answer. I did not get to it but I believe that when I don't put the address of operator (&) it says something about parameter 1 not being right. That's why I used &RadarParityTable. I'll check again if I have time tomorrow. I know that parameter 1 should be a void pointer. Thanks
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*(p - 1) = ' '; will put a space character in the byte imedieatly preceeding the location pointed to by p. If p is a pointer to the location after your buffer, the last character of your buffer will become a 0x20 (space character).
Yes. That space however is going to the end of the wrong array, RadarParityTable. I have to parse another buffer, a file header, and treat the data differently when it encounters two spaces. Because strtok puts a 0x00 or '\0' at the end of each substring where the token exists, the data will be in EBCDIC when written to disk, I had to replace the spaces that strtok put into it. So, I did as you say put a space preceding the spot where strtok found the next substring of data. I must be corrupting that memory somehow, though boundschecker active mode is not catching it. Its funny though that changing the size of the RadarParityTable from 4096 to 4097 fixed the problem.
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JohnnyG wrote: memset(&RadarParityTable, 0, sizeof(RadarParityTable)); to memset(RadarParityTable, 0, sizeof(RadarParityTable)); Did you corrected this ??? Hth....;) Ramu
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Sorry, I didn't answer. I did not get to it but I believe that when I don't put the address of operator (&) it says something about parameter 1 not being right. That's why I used &RadarParityTable. I'll check again if I have time tomorrow. I know that parameter 1 should be a void pointer. Thanks
What error message does it exactly give ??? Using '&' is not correct. Thanks, Ramu
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What error message does it exactly give ??? Using '&' is not correct. Thanks, Ramu
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I've created an array of unsigned chars as a parity table. During program initialization, I originally memset the array to all zeros. In the same init sequence, I set elements of the array to one to signify that the parity bit should be set for that particular value. // in header file #define RADAR_PARITYTBLSZ 4096 unsigned char RadarParityTable[RADAR_PARITYTBLSZ]; // in .C file // Initialize parity table for 12 bit radar msgs and 1 bit of parity memset(&RadarParityTable, 0, sizeof(RadarParityTable)); for(i = 0; i < RADAR_PARITYTBLSZ; i++) if(ComputeParity(i) == 0) // this returns 0 if value of i is even RadarParityTable[i] = 1; The problem is that the last element of the array, in this case [4095], (the array is 4096 bytes in size, is mysteriously set to 0x20 instead of 1. I'm using odd parity so the parity for a value of 0xfff or 4095 -- 12 binary bits set means add one to it to make it odd. I set a breakpoint right after the code above in the init sequence and Quickwatch says ALL of the values are zero. Later when I compare parity to the parity table in another module and use quickwatch, the value for that element is 0x20. The only way I was able to fix this was to increase the size of the array by 1 to 4097, initialize the first 4096 elements the same as before, and then all of the values in the array were correct even the last one. I even tried adding this line of code below in the init sequence but it didn't work. RadarParityTable[RADAR_PARITYTBLSZ-1] = 1; Any ideas why it was set to hex 0x20.
I fixed it. Thanks, everybody. It turns out that on the very first call to strtok and all subsequent calls, I was placing the '\0' that strtok appends to each substring with a space. However, on the first call to strtok, there is no space (my token) before it, and thus I was placing a space into a memory address where my other array's end element existed.