Cosmic Compiler Bug

psilvaggio · ‎2013-03-04

Posted on March 04, 2013 at 16:33

I'm using Cosmic Eval C Compiler V 4.3.7.

The code of concern is as follows:

if( RST->SR & (u8)0x02 == (u8)0x02)

{....}

I'm simply checking bit 1 of the reset register. I checked the disassembler because the program was not working as expected and this is what I found:

main.c:215 if( RST->SR & (u8)0x02 == (u8)0x02){

0x9272 <.ckResetForIWDG+12> 0xC650B3 LD A,0x50b3 LD A,0x50b3

0x9275 <.ckResetForIWDG+15> 0xA501 BCP A,#0x01 BCP A,#0x01

0x9277 <.ckResetForIWDG+17> 0x275F JREQ 0x92d8

.....}

This is clearly why my program will not work as expected, the disassembler tells me that I'm checking bit 0 not bit 1! Am I missing something?

psilvaggio · ‎2013-03-04

Posted on March 04, 2013 at 19:32

I found a work around by using a temp variable to store the result of the AND and compare using the temp variable. However, as far as I know my original bit of code was legal C...

luca239955_stm1_st · ‎2013-03-05

Posted on March 05, 2013 at 10:40

Hello,

the problem is in the source code: as it is written, since the operator == has higher priority than the operator &, the compiler understands it as

if( RST->SR & ( (u8)0x02 == (u8)0x02) )

whereas what you wanted to write is

if( (RST->SR & (u8)0x02) == (u8)0x02 )

which is usually written simply as

if( RST->SR & (u8)0x02 )

Regards.