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Quinni
Joined: 24 Mar 2006
Posts: 1
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| Problem w. built-in function toupper (convert to uppercase) |
 Posted: Fri Mar 24, 2006 11:21 am |
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Hi,
Does anyone know why the line
strnew[i]=toupper(*ptr);
does not work? It works in every ANSI C-Compiler but not with the CCS-Compiler. Its a simple task converting a char to uppercase.
I have found the work around you can see below, but i would like to know why the specific line does not work.
This is only a code fragment - all pointers and variables are set correctly!
Thx for any answer.
Quinni
char c;
char * ptr;
This does NOT Work
strnew[i]=toupper(*ptr); // this line does not work as i expect
//convert to uppercase and store it in a new string
This Code works:
c=*ptr; //first store dereferenced pointer to c
strnew[i]=toupper(c); //convert c to uppercase and store it in new string |
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treitmey
Joined: 23 Jan 2004
Posts: 1094
Location: Appleton,WI USA
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| Posted: Fri Mar 24, 2006 12:39 pm |
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..
Last edited by treitmey on Fri Mar 24, 2006 4:05 pm; edited 1 time in total |
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PCM programmer
Joined: 06 Sep 2003
Posts: 21708
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| Posted: Fri Mar 24, 2006 2:51 pm |
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It looks like the problem occurs when the result from toupper()
is assigned to an array with a variable index. Look at the test
program shown below. It produces the results shown below. It's only
incorrect in the 2nd test. I tested this with PCM vs. 3.248 and 3.449.
| Code: |
first result = 41
2nd result = 61 <-- incorrect
3rd result = 41
(Values are in Hex)
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| Code: |
#include <16F877.H>
#fuses XT, NOWDT, NOPROTECT, BROWNOUT, PUT, NOLVP
#use delay(clock=4000000)
#use rs232(baud=9600, xmit=PIN_C6, rcv=PIN_C7, ERRORS)
//============================
void main()
{
char *ptr;
char c;
char string[10] = {"a"};
char strnew[10];
int8 i;
ptr = string;
c = toupper(*ptr);
printf("first result = %x \n\r", c);
i = 0;
ptr = string;
strnew[i] = toupper(*ptr);
printf("2nd result = %x \n\r", strnew[0]);
ptr = string;
strnew[0] = toupper(*ptr);
printf("3rd result = %x \n\r", strnew[0]);
while(1);
} |
=======================
I don't have time to investigate this right now. I've got to
do some work at the company. But as a work-around you can
use the following replacement function for toupper(). I tested
it with the program above and it always works.
| Code: |
char my_toupper(char c)
{
if(c >= 'a' && c <= 'z')
c -= 0x20;
return(c);
} |
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Ttelmah
Guest
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| Posted: Sat Mar 25, 2006 9:02 am |
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Yes, it a definite bug.
If you look at the assembler generated, in the specific case of using a pointer reference on both sides of the equation (remember in C an array, and pointer are just two different constructs giving the same result), with a variable index on the left side, the code generates:
| Code: |
.................... strnew[i] = (toupper(*ptr));
00BE: MOVLW 2D
00BF: ADDWF 37,W
00C0: MOVWF 38
00C1: MOVF 21,W
00C2: MOVWF 04
00C3: MOVF 00,W
00C4: MOVWF 39
00C5: SUBLW 60
00C6: BTFSC 03.0
00C7: GOTO 0CF
00C8: MOVF 39,W
00C9: SUBLW 7A
00CA: BTFSS 03.0
00CB: GOTO 0CF
00CC: MOVF 39,W
00CD: ANDLW DF //Correctly generates result
00CE: GOTO 0CF
00CF: MOVF 38,W //Uurgh, W is now destroyed
00D0: MOVWF 04
00D1: MOVF 39,W //Retreive the original value...
00D2: MOVWF 00 //and save this.
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I'd report this, but in the meantime, probably use:
| Code: |
#define toupper(x) ((x)>='a' && (x)<='z')?(x&0xDF):(x)
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Which has the advantage of 'overwriting' the existing declaration, without having to change the rest of the code (though produces slightly bulkier code).
Best Wishes |
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