TAILIEUCHUNG - ARM Architecture Reference Manual- P6

ARM Architecture Reference Manual- P6: The ARM instruction set architecture has evolved significantly since it was first developed, and will continue to be developed in the future. In order to be precise about which instructions exist in any particular ARM implementation, five major versions of the instruction set have been defined to date. | ARM Instructions Operation if ConditionPassed cond then if address 1 0 0b00 Rd Memory address 4 else if address 1 0 0b01 Rd Memory address 4 Rotate_Right 8 else if address 1 0 0b10 Rd Memory address 4 Rotate_Right 16 else address 1 0 0b11 Rd Memory address 4 Rotate_Right 24 Usage LDRT can be used by a privileged exception handler that is emulating a memory access instruction that would normally execute in User mode. The access is restricted as if it had User mode privilege. Notes User mode If this instruction is executed in User mode an ordinary User mode access is performed. Operand restrictions If the same register is specified for Rd and Rn the results are UNPREDICTABLE. Data abort F or details of the effects of the instruction if a data abort occurs see Effects of data-aborted instructions on page A2-17. Alignment If an implementation includes a System Control coprocessor See Chapter B2 The System Control Coprocessor and alignment checking is enabled an address with bits 1 0 0b00 causes an alignment exception. ARM DDI 0100E Copyright 1996-2000 ARM Limited. All rights reserved. A4-51 ARM Instructions MCR 31 28 27 26 25 24 23 21 20 19 16 15 12 11 87 543 0 cond 1110 opcode_1 0 CRn Rd cp_num opcode_2 1 CRm The MCR Move to Coprocessor from ARM Register instruction passes the value of register Rd to the coprocessor whose number is cp_num. If no coprocessors indicate that they can execute the instruction an Undefined Instruction exception is generated. Syntax MCR cond coproc opcode_1 Rd CRn CRm opcode_2 MCR2 coproc opcode_1 Rd CRn CRm opcode_2 where cond Is the condition under which the instruction is executed. The conditions are defined in The condition field on page A3-5. If cond is omitted the AL always condition is used. MCR2 Causes the condition field of the instruction to be set to 0b1111. This provides additional opcode space for coprocessor designers. The resulting instructions can only be executed unconditionally. coproc Specifies the name of the .

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