HD6475328CG Datasheet, PDF (99/459 Pages) Hitachi Semiconductor – Manual Gives a Hardware Description

ΠA one-byte variable (char or unsigned char) is declared as a register variable.
 The variable declared as in Œ is squared by compound substitution
Example: register char a;
a _*= a;
• Solution
The problem can be avoided as follows:
ΠIn the example above, do not declare the variable (a) as a register variable.
Example: register char a;
→ char a;
a _*= a;
a _*= a;
 When squaring one-byte data, do not use compound substitution. Code as follows:
Example: a _*= a;
→
a = a _* a;
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