ARM VERSION 1.2 - Manual (Page 38)

Writing ARM and Thumb Assembly Language
2-26 Copyright © 2000, 2001 ARM Limited. All rights reserved. ARM DUI 0068B
2.6.1 Direct loading with MOV and MVN
In ARM state, you can use the MOV and MVN instructions to load a range of 8-bit constant
values directly into a register:
• MOV can load any 8-bit constant value, giving a range of 0x0 to 0xFF (0-255).
It can also rotate these values by any even number. Table 2-4 shows the range of
values that this provides.
• MVN can load the bitwise complement of these values. The numerical values are
-(n+1) , where n are the values given in Table 2-4.
You do not need to calculate the necessary rotation. The assembler performs the
calculation for you.
You do not need to decide whether to use MOV or MVN . The assembler uses whichever is
appropriate. This is useful if the value is an assembly-time variable.
If you write an instruction with a constant that cannot be constructed, the assembler
reports the error:
Immediate n out of range for this operation .
The range of values shown in Table 2-4 can also be used as one of the operands in
data-processing operations. You cannot use their bitwise complements as operands, and
you cannot use them as operands in multiplication operations.
Table 2-4 ARM-state immediate constants
Rotate Binary Decimal Step Hexadecimal
No rotate 000000000000000000000000xxxxxxxx 0-255 1 0-0xFF
Right, 30 bits 0000000000000000000000xxxxxxxx00 0-1020 4 0-0x3FC
Right, 28 bits 00000000000000000000xxxxxxxx0000 0-4080 16 0-0xFF0
Right, 26 bits 000000000000000000xxxxxxxx000000 0-16320 64 0-0x3FC0
... ... ... ...
Right, 8 bits xxxxxxxx000000000000000000000000 0-255 x 2 24 2 24 0-0xFF000000
Right, 6 bits xxxxxx000000000000000000000000xx - - -
Right, 4 bits xxxx000000000000000000000000xxxx - - -
Right, 2 bits xx000000000000000000000000xxxxxx - - -