2.6.3.3.1 Constant
You specify an Operand2 constant in the form:
#constant
where constant can be:
- any constant that can be produced by shifting an 8-bit value left by any number of bits within a 32-bit word
- any constant of the form 0x00XY00XY
- any constant of the form 0xXY00XY00
- any constant of the form 0xXYXYXYXY
In the constants shown above, X and Y are hexadecimal digits.
In addition, in a small number of instructions, constant can take a wider range of values. These are described in the individual instruction descriptions.
When an Operand2 constant is used with the instructions
MOVS, MVNS, ANDS,
ORRS, ORNS, EORS,
BICS, TEQ or TST, the carry flag is
updated to bit[31] of the constant, if the constant is greater than 255 and can be produced
by shifting an 8-bit value. These instructions do not affect the carry flag if
Operand2 is any other constant.
Instruction substitution
Your assembler might be able to produce an equivalent instruction in cases
where you specify a constant that is not permitted. For example, an assembler might
assemble the instruction CMP Rd, #0xFFFFFFFE as the equivalent instruction
CMN Rd, #0x2.