The Art of Assembly Language, 2nd Edition

10.13 The HLA Standard Library Bits Module

The HLA Standard Library provides the bits.hhf module that provides several bit-related functions, including built-in functions for many of the algorithms we've studied in this chapter. This section describes some of the functions available in the HLA Standard Library.

procedure bits.cnt( b:dword ); @returns( "eax" );

This procedure returns the number of 1 bits present in the b parameter. It returns the count in the EAX register. To count the number of 0 bits in the parameter value, invert the value of the parameter before passing it to bits.cnt. If you want to count the number of bits in a 16-bit operand, simply zero extend it to 32 bits prior to calling this function. Here are a couple of examples:

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