Propeller Manual

LONG – Spin Language Reference
Page 128 · Propeller Manual v1.1
LONG
Designator: Declare long-sized symbol, long aligned/sized data, or read/write a long of main
memory.
VAR
LONG Symbol 〈[Count ]〉
DAT
〈Symbol〉 LONG Data 〈[Count]〉
((PUB ┆ PRI))
LONG [BaseAddress] 〈[Offset ]〉
• Symbol is the desired name for the variable (Syntax 1) or data block (Syntax 2).
•
Count is an optional expression indicating the number of long-sized elements for
Symbol (Syntax 1) or the number of long-sized entries of Data (Syntax 2) to store in
a data table.
•
Data is a constant expression or comma-separated list of constant expressions.
•
BaseAddress is an expression describing the long-aligned address of main memory to
read or write. If Offset is omitted, BaseAddress is the actual address to operate on. If
Offset is specified, BaseAddress + Offset * 4 is the actual address to operate on.
•
Offset is an optional expression indicating the offset from BaseAddress to operate on.
Offset is in units of longs.
Explanation
LONG is one of three multi-purpose declarations (BYTE, WORD, and LONG) that declares or
operates on memory.
LONG can be used to:
1) declare a long-sized (32-bit) symbol or a multi-long symbolic array in a
VAR block, or
2) declare long-aligned, and/or long-sized, data in a
DAT block, or T
3) read or write a long of main memory at a base address with an optional offset.
Range of Long
Memory that is long-sized (32 bits) can contain a value that is one of 2
32
possible
combinations of bits (i.e., one of 4,294,967,296 combinations). The Spin language performs
all mathematic operations using 32-bit signed math, meaning every long value is considered
to be in the range -2,147,483,648 to +2,147,483,647. However, the actual numeric value
contained within a long is subject to how a computer and user interpret it. In Propeller
Assembly a long value can be treated as both signed and unsigned.