Directive: Remove, "truncate," the fractional portion from a floating-point constant.

((CON ┆ VAR ┆ OBJ ┆ PUB ┆ PRI ┆ DAT))
  TRUNC ( FloatConstant )

Returns: Integer that is the given floating-point constant value truncated at the decimal point.

• FloatConstant is the floating-point constant expression to be truncated to an integer.

Explanation

TRUNC is one of three directives (FLOAT, ROUND and TRUNC) used for floating-point constant expressions. TRUNC returns an integer constant that is the given floating-point constant expression with the fractional portion removed.

Using TRUNC

TRUNC can be used to retrieve the integer portion of a floating-point constant. For example:

CON
  OneHalf     = 0.5
  Bigger      = 1.4999
  Int1        = trunc(OneHalf)
  Int2        = trunc(Bigger)
  Int3        = trunc(Bigger * 10.0) + 4 

The above code creates two floating-point constants, OneHalf and Bigger, equal to 0.5 and 1.4999, respectively. The next three constants, Int1, Int2 and Int3, are integer constants that are based on OneHalf and Bigger using the TRUNC directive. Int1 = 0, Int2 = 1, and Int3 = 18.

About Floating-Point Constants

The Propeller compiler handles floating-point constants as a single-precision real number as described by the IEEE-754 standard. Single-precision real numbers are stored in 32 bits, with a 1-bit sign, an 8-bit exponent, and a 23-bit mantissa (the fractional part). This provides approximately 7.2 significant decimal digits.

Floating-point constant expressions can be defined and used for many compile-time purposes, but for run-time floating-point operations, the FloatMath and FloatString objects provide math functions compatible with single-precision numbers. See the Constant Assignment '=', FLOAT, and ROUND, as well the FloatMath and FloatString objects for more information.