Compiler problem again?

[lseletron]

Posted on July 31, 2007 at 10:32

Compiler problem again?

[lseletron]

Posted on July 30, 2007 at 04:38

Hi,

I followed Luca's recommendation and installed the latest Cosmic compiler. Now the .ls file says at the beginning:

1 ; C Compiler for ST7 (COSMIC Software)

2 ; Generator V4.5.5 - 12 Jan 2006

3 ; Optimizer V4.4.2 - 11 Jan 2006

But I still have problems with my program. In the following code

line 1:unsigned char l_ShortAddress;

line ;

line 3:if(((g_DaliPacket[DALI_ADDRESS_BYTE]&0b011111110)>>1)==g_MyDaliSettings.m_ShortAddress)

line 4:{

line 5:retval=DALI_NORMAL_COMMAND_FOR_ME;

line 6:}

line 5 will not be executed as it should. I fix the problem by uncommenting line 2, which is weird as line 2 does nothing useful.

Here is the translation for both cases (line 2 commented and not commented):

// Commented, not working properly:

2788 switch .text

2790 xref _IsDaliPacketForMe$L

2791 0cf5 _IsDaliPacketForMe:

2792 ; 1294 unsigned char retval=DALI_COMMAND_NOT_FOR_ME;

2793 0cf5 a601 ld a,#1

2794 0cf7 c7ffff ld _IsDaliPacketForMe$L-1,a

2795 ; 1296 if (0==GetBit(g_DaliPacket[DALI_ADDRESS_BYTE],B_7))

2796 0cfa c6003f ld a,_g_DaliPacket

2797 0cfd 2b17 jrmi L306

2798 ; 1301 if(((g_DaliPacket[DALI_ADDRESS_BYTE]&0b011111110)>>1)==g_MyDaliSettings.m_ShortAddress)

2799 0cff 5f clr x

2800 0d00 90ce0028 ld y,_g_MyDaliSettings+4

2801 0d04 3f00 clr c_y

2802 0d06 b300 cp x,c_y

2803 0d08 2703cc0da6 jrne L706

2804 0d0d 90bf01 ld c_y+1,y

2805 0d10 b101 cp a,c_y+1

2806 0d12 26f6 jrne L706

2807 ; 1303 retval=DALI_NORMAL_COMMAND_FOR_ME;

// Not commented working OK

2788 switch .text

2790 xref _IsDaliPacketForMe$L

2791 0cf5 _IsDaliPacketForMe:

2792 ; 1294 unsigned char retval=DALI_COMMAND_NOT_FOR_ME;

2793 0cf5 a601 ld a,#1

2794 0cf7 c7ffff ld _IsDaliPacketForMe$L-1,a

2795 ; 1296 if (0==GetBit(g_DaliPacket[DALI_ADDRESS_BYTE],B_7))

2796 0cfa c6003f ld a,_g_DaliPacket

2797 0cfd 2b1b jrmi L306

2798 ; 1300 l_ShortAddress=g_MyDaliSettings.m_ShortAddress;

2799 0cff c60028 ld a,_g_MyDaliSettings+4

2800 0d02 c7fffe ld _IsDaliPacketForMe$L-2,a

2801 ; 1301 if(((g_DaliPacket[DALI_ADDRESS_BYTE]&0b011111110)>>1)==g_MyDaliSettings.m_ShortAddress)

2802 0d05 5f clr x

2803 0d06 9097 ld y,a

2804 0d08 3f00 clr c_y

2805 0d0a b300 cp x,c_y

2806 0d0c 2703cc0daa jrne L706

2807 0d11 90bf01 ld c_y+1,y

2808 0d14 b101 cp a,c_y+1

2809 0d16 26f6 jrne L706

2810 ; 1303 retval=DALI_NORMAL_COMMAND_FOR_ME;

Why does this happen?

I am doing something wrong?

Thanks

[jpl2]

Posted on July 31, 2007 at 10:32

Hi,

There is an optimizer problem here. You should try a more efficient syntax by casting the result of the shift back to (unsigned char), as the C standard rules are considering the result of any operator as at least an int. Forcing the shift result to a char will allow a direct char compare and the optimizer will not fail with the widening:

if((unsigned char)((g_DaliPacket[DALI_ADDRESS_BYTE]&0b011111110)>>1)==g_MyDaliSettings.m_ShortAddress)

And the resulting code will be more efficient.