14.9: Chapter Summary

Pharo uses 2’s complement encoding for its internal small integer representation and supports bit manipulation of their internal representation. This is useful when we want to speed up algorithms using simple encoding. We have reviewed the following points:

• Numerical values use complement to encode their negative value.
• Shifting a bit to the left multiple is equivalent to multiply it by 2, modulo the maximum value of its encoding size.
• On the opposite, shifting a bit to the right divides it by 2.
• Bits operations can be performed on any numerical values.
• Complement are useful to turn an addition into a subtraction, thus simplifying the operation.
• SmallInteger are coded on 31 bits on Pharo.

Note that Pharo supports large numbers whose limit in size is mainly the memory you have at your disposal.

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