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Bitwise logical AND stores in a bit ....

Hi,

I get a curious result when compiling such a following code :

typedef union  {

  unsigned char                cCtrlFullByte;

  struct {
    unsigned char  bEnable          : 1;
    unsigned char  cUnused          : 7;

  }  cCtrlStruct;
} CtrlUnion;

void main (void)  {

    unsigned char  dummy = 0x55;
    CtrlUnion  xdata    bitUnion;

    bitUnion.cCtrlStruct.bEnable = dummy & 0x40;

    return;
}

It results in :

MOV A,#0x55
ANL A,#0x00
MOV R7,A
MOV DPTR, #0x0000
MOVX A,@DPTR
ANL A,#0xFE
ORL A,R7
MOVX @DPTR, A

I thought that the bit result of bitwise logical AND is 1 if result is not 0, else 0.
It seems that I didn't understand ANSI the same way than Keil compiler ? Am I wrong ?

Arnaud DELEULE

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0 Norbert Paul over 23 years ago in reply to Mark Odell
I'm aware.

These aren't really variables. I dont see any possibility
for an implementation to interfere with _mbr in:

struct {some_type_here _mbr;} variable;

It could be any prefix as well. I just wanted someprefix
for my little digits to lean on.

Norbert
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0 Norbert Paul over 23 years ago in reply to Mark Odell
I'm aware.

These aren't really variables. I dont see any possibility
for an implementation to interfere with _mbr in:

struct {some_type_here _mbr;} variable;

It could be any prefix as well. I just wanted someprefix
for my little digits to lean on.

Norbert
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0 Mark Odell over 23 years ago in reply to Norbert Paul

If I write a compiler and have some internal _mbr variable used in one of my libraries it would be within my right. Then you'd have a problem. My point is, never use _ as a leading char in anything. It's just safer.

- Mark
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