360 Assembly/360 Instructions/LR
LR - Load Register - RR Instruction - Opcode 18
- LR 2,6 Copy the contents of register 6 into register 2, replacing the existing contents of register 2
The specific syntax is
- LR target register, source register.
|RR Instruction (2 bytes)|
0..F / (dec 0..15)
0..F / (dec 0..15)
- The first argument is a target register which value is affected by the instruction.
- The second argument is the source register.
- The target register and source register values are 0 to 15.
The LR instruction is used to copy the contents of the second register argument (the source register) into the first register argument (the target register), replacing the contents of the target register with the contents of the source register. The following is an example of how the instruction would assemble in various forms from an assembly language listing:
1826 LR 2,6 1892 LR 9,2 18FA LR 15,10
When it is necessary to copy the contents of a register in order to preserve the value in the original register, or where the purpose is to propagate the value contained in one register to another register.
The LR instruction is available on all models of the 360, 370 and z/System.
The LR instruction copies the 32-bit value from the register specified by the second argument to the register specified by the first argument.
Register 0 is valid for either register and is not ignored as in some other instructions.
Condition codes are not changed.
Exceptions and Faults
Since LA does not access memory, but only calculates a number, which can, but does not have to be, an address, the most closely related instruction is probably ALR - Add Logical Register. To think about it, LA calculates a number, L loads a value from memory. To think of LA as being related to Load instructions is neither proper, nor helpful.
- To load an 8-bit byte (character) value from memory, see IC.
- To load one or more 8-bit byte values into a register according to a mask, see ICM
- To load a 16-bit half-word value from memory, see LH.
- To load a 12-bit unsigned value into a register or add up to 4095 to the values in one or two 32-bit registers, see LA.
- To copy a 32-bit word value from one register to another register, see LR.
- To load a 32-bit word value from memory, see L.
- To store an 8-bit byte (character) value in memory, see STC.
- To store one or more 8-bit byte values into memory according to a mask, see STCM
- To store a 16-bit half-word value in memory, see STH.
- To store a 32-bit word value in memory, see ST.
- To load a 20-bit signed value into a 32-bit or 64-bit register from an extended (20-bit) signed memory offset, see LAY.
- To load a 32-bit value into a 64-bit register from an extended (20-bit) signed memory offset, see LGF.
- To copy a 64-bit value from one 64-bit register to another 64-bit register, see LGR.
- To load a 64-bit value into a 64-bit register from memory, see LG.
- To store a 32-bit value from a register to an extended (20-bit) signed memory offset, see STY.
- To store a 64-bit value from a 64-bit register to an address in memory, see STG.
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