left shift in bits

hello, i want to perform left shift by 1 bit in this code for left_1 and right_1

%    1 2 3 4 5 6 7 8 9 10
key=[1 0 1 0 0 0 0 0 1 0]
IP=[3 5 2 7 4 10 1 9 8 6]
left=key(IP(1:5))  
left_1=left
right=key(IP(6:10))  
right_1=right

[James Tursa]

What kind of shift? Circular shift? Fall-off-the-end shift? Shift bits to/from "left" variable and "right" variables?

[ablaze]

circular shift

[Walter Roberson]

How many bits width?

Answer 1

[Walter Roberson]

Multiply by 2.

[Walter Roberson]

For 4 bits (as your values are small):

shifted = pre_shifted * 2;
mask = shifted >= 16;
shifted(mask) = shifted(mask) - 15;