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
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.
8.6 Glossary
8.6.1 Double-Number words
8.6.2 Double-Number extension words