hello, I would like to do a bit test of a unsigned char variable. It's like a jb in assembler.
here is my code in c.
unsigned char displ; unsigned char display3 = 0xA8; unsigned char i; sbit display_data = P1^0; displ = display3; for (i=0; i<7; i++) { if (displ^0 == 1){ display_data = 0; } else { display_data = 1; } displ>>=1; }
I don't have any warning or error, but the result of test is wrong. is it possible to do in c?
tkx.
This slightly modified example does what you want:
C51 COMPILER V8.08a, COMPILATION OF MODULE DISPL OBJECT MODULE PLACED IN displ.OBJ COMPILER INVOKED BY: c51.exe displ.c CODE line level source 1 unsigned char displ; 2 unsigned char display3 = 0xA8; 3 unsigned char i; 4 sfr P1 = 0x90; 5 sbit display_data = P1^0; 6 7 void test (void) { 8 1 displ = display3; 9 1 for (i = 0 ; i < 7; ++i ) { 10 2 if (displ & 0x01) { // (displ^0 == 1){ 11 3 display_data = 0; 12 3 } 13 2 else { 14 3 display_data = 1; 15 3 } 16 2 displ >>= 1; 17 2 } 18 1 } ; FUNCTION test (BEGIN) ; SOURCE LINE # 7 ; SOURCE LINE # 8 0000 850000 R MOV displ,display3 ; SOURCE LINE # 9 0003 E4 CLR A 0004 F500 R MOV i,A 0006 ?C0001: ; SOURCE LINE # 10 0006 E500 R MOV A,displ 0008 30E004 JNB ACC.0,?C0004 ; SOURCE LINE # 11 000B C290 CLR display_data ; SOURCE LINE # 12 000D 8002 SJMP ?C0005 000F ?C0004: ; SOURCE LINE # 13 ; SOURCE LINE # 14 000F D290 SETB display_data ; SOURCE LINE # 15 0011 ?C0005: ; SOURCE LINE # 16 0011 E500 R MOV A,displ 0013 C3 CLR C 0014 13 RRC A 0015 F500 R MOV displ,A ; SOURCE LINE # 17 0017 0500 R INC i 0019 E500 R MOV A,i 001B B407E8 CJNE A,#07H,?C0001 ; SOURCE LINE # 18 001E ?C0006: 001E 22 RET ; FUNCTION test (END)
I detest the use of
for (i = 0 ; i < 7; ++i ) { instead of for (i = 0 ; i < 7; ++i ) {
Is it just me that consider that style rendering the code unreadable?. In my opininion any '{' should be in the same column as the matchibg '}'
now that I have been 'mean', let me be 'kind'
instead of
if (displ^0 == 1) use sbit Ralph displ^0 .... if (Ralph)
Erik
"I detest the use of..."
It is purely a matter of style - and such debates always produce strong opinions.
Others would say that they detest the useless waste of a line with just a '{' on it, that it unnecessarily breaks up the code, etc, etc...
"Is it just me that consider that style rendering the code unreadable?"
I don't know about "unreadable", but I also dislike it.
However, this style has extremely good credentials - it's what messrs Kernighan & Ritchie themselves use in their definitive work on the subject!
c-faq.com/.../layout.html
I used to detest that K&R style also, but after contracting for so many companies, each invariably with different coding style rules, I've learned to be at peace with whatever as long as it's consistent. For forum posts however, I have adopted the K&R style for the simple reason of conserving vertical space in threads.
Right now, I'm contracting to the same outfit where the K and the R of K&R work, so guess which brace style I'm using at present. ;-)
This is not quite as K&R would have it:
for (i=0; i<7; i++) { if (displ^0 == 1){ display_data = 0; } else { display_data = 1; } displ>>=1; }
"True" K&R style would be:
The "controlled" lines are indented relative to the "controlling" lines.
I guess they did that to illustrate the lf/cr independence of C.
so, this would be step one towards the 'ultimate' C program (the whole shebang in one line)
OK, I agree that on matters of style everybody has a (different) opinion and the only reason I happened to bring it up was that this particular 'style' threw me off a bit in this case. I appreciate getting one 'yes' (makes me feel not crazy [in this respect]) and let us leave it at that.
PS re 'conserving linespace' I often do this if (blah) { // since blah is set .....
"PS re 'conserving linespace' I often do this if (blah) { // since blah is set ....."
Yes - so do I!
The comment aligns with the indented text:
if( condition ) { // Condition is true - time to do stuff do_stuff(); do_other_stuff(); etc(); }
well, fortunately, while we have to adhere to the syntax, we are free to improve on the style.
I have a lingering suspicion that K&R are, at least partially, responsible for much of the "elegant" C that abounds
PS if anyone does not get that I am fastidious when stating "elegant" the are now told.