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RENESAS TOOL NEWS on April 16, 2008: 080416/tn1
| A Note on Using the C Compiler Packages
for the R32C/100 and the M32C Series of MCUs |
Please take note of the following problem in using the C compiler package
for the R32C/100 series, M16C family, and the one for the M32C series* of
MCUs, M3T-NC308WA:
- With issuing preprocessing directive #pragma DMAC to extend the C compiler's functionality
*The M32C series is the generic name of the M32C/80 and M16C/80 series.
1. Products and Versions Concerned
(1) C compiler package for the R32C/100 series
V.1.01 Release 00
(2) C compiler package for the M32C series (M3T-NC308WA)
V.5.00 Release 1 through V.5.41 Release 01
2. Description
If a variable specified with #pragma DMAC is used in a controlling
expression, assemble errors may arise.
3. Conditions
This problem occurs if the following conditions are all satisfied:
(1) Any of the optimizing options -O1, -O2, -O3, -O4, -O5, -OR, -OS,
-OR_MAX and -OS_MAX are selected.
(2) An external variable is specified with #pragma DMAC.
(3) The external variable in (2) and an integer constant are bitwise-
ANDed in the controlling expression in an if, while, or for
statement.
(4) The integer constant in (3) is 2 to the nth power (1, 2, 4, 8, etc).
Example in C compiler package for R32C/100 series:
---------------------------------------------------------------------
unsigned char val;
unsigned long dmd0;
#pragma DMAC dmd0 DMD0 /* Condition (2) */
void func(void)
{
if(dmd0 & 0x00000001L) { /* Conditions (3) and (4) */
val++;
}
}
---------------------------------------------------------------------
4. Workaround
Assign the variable specified with #pragma DMAC to a temporary variable,
and then evaluate it in the controlling expression.
Example:
---------------------------------------------------------------------
unsigned char val;
unsigned long dmd0;
#pragma DMAC dmd0 DMD0
void func(void)
{
unsigned long tmp;
tmp = dmd0; /* Assigned to tmp */
if(tmp & 0x00000001L) {
val = 0x1;
}
}
---------------------------------------------------------------------
5. Schedule of Fixing the Problem
We plan to fix this problem in the next release of the products.
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