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RENESAS TOOL NEWS on April 16, 2004: RSO-M3T-NC308WA-040416D
A Note on Using C-Compiler Package
M3T-NC308WA
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Please take note of the following problem in using the M3T-NC308WA C-compiler package for the M32C/80 and M16C/80 series MCUs:
- On a division or remainder operation including a variable or constant of type long long
- Versions Concerned
M3T-NC308WA V.5.00 Release 1 through V.5.20 Release 1
- Description
Performing a division or remainder operation including a variable or
constant of type long long overwrites the contents of the address registers incorrectly.
- Conditions
This problem occurs if the following two conditions are satisfied:
| (1) |
In the program exists a division or remainder operation. |
| (2) |
Either the dividend or the divisor in operation (1) is a variable or constant of type signed/unsigned long long.
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- 3.1 Example
--------------------------------------------------------------
#include <stdio.h>
const char far ch[10] = "Hello\n";
long long func1(long long ll1,long long ll2)
{
long long ll3;
ll3 = ll1 / ll2; /* Conditions (1) and (2) */
return ll3;
}
int main(void)
{
long long ll;
int far *i;
i = ch;
ll = func1( 2000, 1000 );
printf( "%s\n",i );
}
--------------------------------------------------------------
- Workaround
Use the #pragma ASM--#pragma ENDASM directive or an asm() function in
the inline assemble functions to save address registers A0 and A1 on the
stack before a division or remainder operation begins; then recover them
immediately after the operation ends.
Example:
---------------------------------------------------------------------
#include <stdio.h>
const char far ch[10] = "Hello\n";
long long func1(long long ll1,long long ll2)
{
long long ll3;
asm( " pushm A0,A1" ); /* Save A0 and A1 */
ll3 = ll1 / ll2;
asm( " popm A0,A1" ); /* Recover A0 and A1 */
return ll3;
}
int main(void)
{
long long ll;
int far *i;
i = ch;
ll = func1( 2000, 1000 );
printf( "%s\n",i );
}
---------------------------------------------------------------------
- Schedule of Fixing the Problem
We plan to fix this problem in our next release of the product.
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