Encoding:

Format:

LD rt, offset(base)

Purpose:

Load Doubleword

To load a doubleword from memory

Description:

 GPR[rt] = memory[GPR[base] + offset]

The contents of the 64-bit doubleword at the memory location specified by the aligned effective address are fetched and placed in GPR rt. The 16-bit signed offset is added to the contents of GPR base to form the effective address.

Restrictions:

Pre-Release 6: The effective address must be naturally-aligned. If any of the 3 least-significant bits of the address is non-zero, an Address Error exception occurs.

Release 6 allows hardware to provide address misalignment support in lieu of requiring natural alignment.

Note: The pseudocode is not completely adapted for Release 6 misalignment support as the handling is implementation dependent.

Operation:

vAddr = sign_extend(offset) + GPR[base]
(pAddr, CCA) = AddressTranslation (vAddr, DATA, LOAD)
memdoubleword = LoadMemory (CCA, DOUBLEWORD, pAddr, vAddr, DATA)
GPR[rt] = memdoubleword

Exceptions:

TLB Refill, TLB Invalid, Bus Error, Address Error, Reserved Instruction, Watch