P60ARM-B/IG/GP1N Zarlink Semiconductor, Inc., P60ARM-B/IG/GP1N Datasheet - Page 32

• Manufacturer Part Number: P60ARM-B/IG/GP1N
• Description: A Low Power, General Purpose 32 Bit RISC Microprocessor
• Manufacturer: Zarlink Semiconductor, Inc.

P60ARM-B
(5)
(6)
(7)
Note that the zero in bit 7 of an instruction with a register controlled shift is compulsory; a one in this bit
will cause the instruction to be a multiply or undefined instruction.
4.4.3 Immediate operand rotates
The immediate operand rotate field is a 4 bit unsigned integer which specifies a shift operation on the 8 bit
immediate value. This value is zero extended to 32 bits, and then subject to a rotate right by twice the value
in the rotate field. This enables many common constants to be generated, for example all powers of 2.
4.4.4 Writing to R15
When Rd is a register other than R15, the condition code flags in the CPSR may be updated from the ALU
flags as described above.
When Rd is R15 and the S flag in the instruction is not set the result of the operation is placed in R15 and
the CPSR is unaffected.
When Rd is R15 and the S flag is set the result of the operation is placed in R15 and the SPSR corresponding
to the current mode is moved to the CPSR. This allows state changes which atomically restore both PC and
CPSR. This form of instruction shall not be used in User mode.
4.4.5 Using R15 as an operand
If R15 (the PC) is used as an operand in a data processing instruction the register is used directly.
The PC value will be the address of the instruction, plus 8 or 12 bytes due to instruction prefetching. If the
shift amount is specified in the instruction, the PC will be 8 bytes ahead. If a register is used to specify the
shift amount the PC will be 12 bytes ahead.
4.4.6 TEQ, TST, CMP & CMN opcodes
These instructions do not write the result of their operation but do set flags in the CPSR. An assembler shall
always set the S flag for these instructions even if it is not specified in the mnemonic.
The TEQP form of the instruction used in earlier processors shall not be used in the 32 bit modes, the PSR
transfer operations should be used instead. If used in these modes, its effect is to move SPSR_<mode> to
CPSR if the processor is in a privileged mode and to do nothing if in User mode.
4.4.7 Instruction Cycle Times
Data Processing instructions vary in the number of incremental cycles taken as follows:
28
ASR by 32 or more has result filled with and carry out equal to bit 31 of Rm.
ROR by 32 has result equal to Rm, carry out equal to bit 31 of Rm.
ROR by n where n is greater than 32 will give the same result and carry out as ROR by n-32;
therefore repeatedly subtract 32 from n until the amount is in the range 1 to 32 and see above.
Normal Data Processing
Data Processing with register specified shift
1S
1S + 1I