360 Assembly/360 Instructions/L
L - Load - Opcode 58 - RX format Instruction (32 Bit)
- L 2,N2
- L 11,106(8,10)
The specific syntax is
- L target register,offset(index register,base register)
Where the offset, index register and base register values will be determined automatically by the assembler if the USING pseudo-instruction has been used, and the target address label used is within 4096 bytes of the value of some base register.
|RX Instruction (4 bytes)|
|Byte 1||Byte 2||Bytes 3 and 4|
|target register||Source Address|
|(In Hex)||(8 bits)
- The first argument is a target register which value is affected by the instruction.
- The second argument is the source value location address where the contents are to be loaded into the target register. This consists of a base register, an index register, and a displacement address. The displacement is used as an unsigned offset of 0 to 4095 from the value in the base register, and this displacement is added to the value contained in the base register. If the index register is 0, it is ignored; otherwise, its contents are added to the previous result to obtain the final address.
- The base_register and index_register values are 0 to 15. The offset address is 0 to 4095.
The target and base_register values will be determined automatically by the assembler if the USING pseudo-instruction has been used, and the target address label used (the displacement) is within 4096 bytes of the value of some base register.
The L instruction is available on all models of the 360, 370 and z/System.
The L instruction reads a 32-bit integer value from the memory address specified by the argument and puts it to the register specified by the first argument. The high bits of a 64-bit register are unchanged.
The source argument address shall be aligned to word boundary (i.e. 4 bytes). The Condition Code field in the Program Status Word is not changed.
Exceptions and Faults
- The source address must be within the range of valid memory or an operation exception occurs.
- The source address must be aligned to a word boundary or an address exception occurs.
- The storage key for the source address must be such that the location is readable by the current process (or the process must be privileged with a key of zero) or a memory protect violate exception occurs.
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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