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(int8)a=(int8)b+(int8)c; // how to know if overflow?

 
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future



Joined: 14 May 2004
Posts: 330

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(int8)a=(int8)b+(int8)c; // how to know if overflow?
PostPosted: Sun Jul 11, 2004 3:20 pm     Reply with quote
Without setting "a" to int16 and comparing >255.
ckielstra



Joined: 18 Mar 2004
Posts: 3680
Location: The Netherlands

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PostPosted: Sun Jul 11, 2004 6:09 pm     Reply with quote
How about testing the carry bit in the status register?

Code:
unsigned char STATUS;
#locate STATUS=0x0FD8
#define CARRY_BIT   0

(int8)a=(int8)b+(int8)c;
if (bit_test(status, CARRY_BIT))
{
  // We had an overflow
}


For signed integers you would have to test the Overflow bit (bit 3).
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