8 The optional Double-Number word set

8.1 Introduction

Sixteen-bit Forth systems often use double-length numbers. However, many Forths on small embedded systems do not, and many users of Forth on systems with a cell size of 32 bits or more find that the use of double-length numbers is much diminished. Therefore, the words that manipulate double-length entities have been placed in this optional word set.

8.2 Additional terms and notation

None.

8.3 Additional usage requirements

8.3.1 Text interpreter input number conversion

When the text interpreter processes a number, except a <cnum>, that is immediately followed by a decimal point and is not found as a definition name, the text interpreter shall convert it to a double-cell number.

For example, entering DECIMAL 1234 leaves the single-cell number 1234 on the stack, and entering DECIMAL 1234. leaves the double-cell number 1234 0 on the stack.

See: 3.4.1.3 Text interpreter input number conversion.

8.4 Additional documentation requirements

8.4.1 System documentation

8.4.1.1 Implementation-defined options

no additional requirements.

8.4.1.2 Ambiguous conditions

d outside range of n in 8.6.1.1140 D>S.

8.4.1.3 Other system documentation

no additional requirements.

8.4.2 Program documentation

no additional requirements.

8.5 Compliance and labeling

8.5.1 Forth-2012 systems

The phrase "Providing the Double-Number word set" shall be appended to the label of any Standard System that provides all of the Double-Number word set.

The phrase "Providing name(s) from the Double-Number Extensions word set" shall be appended to the label of any Standard System that provides portions of the Double-Number Extensions word set.

The phrase "Providing the Double-Number Extensions word set" shall be appended to the label of any Standard System that provides all of the Double-Number and Double-Number Extensions word sets.

8.5.2 Forth-2012 programs

The phrase "Requiring the Double-Number word set" shall be appended to the label of Standard Programs that require the system to provide the Double-Number word set.

The phrase "Requiring name(s) from the Double-Number Extensions word set" shall be appended to the label of Standard Programs that require the system to provide portions of the Double-Number Extensions word set.

The phrase "Requiring the Double-Number Extensions word set" shall be appended to the label of Standard Programs that require the system to provide all of the Double-Number and Double-Number Extensions word sets.