Encoding:

Format:

LDC1 ft, offset(base)

Purpose:

Load Doubleword to Floating Point

To load a doubleword from memory to an FPR.

Description:

 FPR[ft] = 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 FPR ft. The 16-bit signed offset is added to the contents of GPR base to form the effective address.

Restrictions:

Pre-Release 6: An Address Error exception occurs if EffectiveAddress_2..0 != 0 (not doubleword-aligned).

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)
paddr = paddr xor ((BigEndianCPU xor ReverseEndian) || 02)
memlsw = LoadMemory(CCA, WORD, pAddr, vAddr, DATA)
paddr = paddr xor 0b100
memmsw = LoadMemory(CCA, WORD, pAddr, vAddr+4, DATA)
memdoubleword = memmsw || memlsw
StoreFPR(ft, UNINTERPRETED_DOUBLEWORD, memdoubleword)

Exceptions:

Coprocessor Unusable, Reserved Instruction, TLB Refill, TLB Invalid, Address Error, Watch