asm rlc versus c shift<<

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embedtechnology

Joined Dec 25, 2015
36
I want to rotate a variable through another variable so that D7 bit of variable 0 will enter into bit D0 position of
variable 1 ( like ASM: rlc variable 0, rlc variable 1 ) . But in c variable0<<=1 loads 0 into D0 position of variable0
and removes bit D7. I am using mikroc compiler.Actually I want to develop a project which is nothing but a led massage
display,in which row scanning technology is taken into consideration. The syntax is needed for scrolling function.
Any idea please.
 

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dannyf

Joined Sep 13, 2015
2,197
Left shift variable 1.
Set or clear variable 1 lsb based on variable 0 msb.
Left shift variable 0.

Fancier ways to do it also exist.
 

NorthGuy

Joined Jun 28, 2014
611
In C, you would probably define a 16-bit variable then do

C:
int x;
x <<= 1;
You can get the result of the shift from the high byte of the variable. In C it is:

C:
char y;
y = x >> 8;
It may look like a long shift, but most compilers will know that it only means taking the high byte.
 
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