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RENESAS TOOL NEWS on March 1, 2004: RSO-M3T-NC30WA_2-040301D
A Note on Using C Compiler
M3T-NC30WA
--On Using Standard Library Function "strcpy"--
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Please take note of the following problem in using C compiler (with an
assembler and integrated development environment) M3T-NC30WA for the M16C/60, M16C/30, M16C/Tiny, M16C/20, M16C/10, and R8C/Tiny series MCUs:
- On using standard library function "strcpy"
- Versions Concerned
M3T-NC30WA V.5.10 Release 1 and V.5.20 Release 1
- Description
Using standard library function "strcpy" may cause System Error to arise.
- Conditions
This problem occurs if the following four conditions are satisfied:
| (1) |
Optimizing options -OS and -O5 are both selected.
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| (2) |
Standard library function "strcpy" is used.
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| (3) |
The first argument of the strcpy function is an expression that contains a pointer-type external variable.
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| (4) |
The second argument of the function is a string literal.
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- Examples
Example 1:
--------------------------------------------------------
#include <string.h>
struct SS {
int i;
char c[20];
};
struct SS *ps;
void func(void)
{
strcpy(ps->c,"abcdefghijkl");
}
--------------------------------------------------------
Example 2:
--------------------------------------------------------
char *p;
void func(void)
{
strcpy(p+2,"abcdefghijkl");
}
--------------------------------------------------------
- Workaround
This problem can be circumvented in either of the following ways:
| (1) |
Replace -O5 with any of those, -O1, O2, O3, and O4.
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| (2) |
Use a dummy asm function as follows:
(a) Define a temporary pointer variable.
(b) Assign the string literal to the pointer variable in (a).
(c) Place a dummy asm function immediately after the assignment in (b).
(d) Pass the temporary pointer variable in (a) to the strcpy function as its second argument.
Example:
--------------------------------------------------------
char *p;
void func(void)
{
const char *tmp;
tmp = "abcdefghijkl";
asm(); /* Dummy asm function */
strcpy(p+2,tmp);
}
--------------------------------------------------------
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- Schedule of Fixing the Problem
We plan to fix this problem in our next release of the product.
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