In the Intel x86 instruction set, for example, there are two ways of doing sign extension: Thus, by padding the left side with ones, the negative sign and the value of the original number are maintained. If ten bits are used to represent the value " 11 1111 0001" (decimal negative 15) using two's complement, and this is sign extended to 16 bits, the new representation is " 1111 1111 1111 0001". Thus, both the value and the fact that the value was positive are maintained. This is done by appending digits to the most significant side of the number, following a procedure dependent on the particular signed number representation used.įor example, if six bits are used to represent the number " 00 1010" (decimal positive 10) and the sign extend operation increases the word length to 16 bits, then the new representation is simply " 0000 0000 0000 1010".
Sign extension (abbreviated as sext) is the operation, in computer arithmetic, of increasing the number of bits of a binary number while preserving the number's sign (positive/negative) and value.
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