Encoding:

Format:

LHX rd, index(base)

LHX rd, rs(rt)

Purpose:

Load Halfword Indexed

To load a halfword value from memory as a signed value, using indexed addressing.

Description:

 rd = memory[base+index]

The contents of GPR index is added to the contents of GPR base to form an effective address. The contents of the 16bit halfword at the memory location specified by the aligned effective address are fetched, sign-extended to the length of the destination GPR, and placed in GPR rd.

Restrictions:

The effective address must be naturally-aligned. If the least-significant bit of the ef fective address is non-zero, an

Address Error exception occurs.

Operation:

ValidateAccessToDSPResources()
vAddr31..0 = GPR[index]31..0 + GPR[base]31..0
if ( vAddr0 != 0 ) then
   SignalException( AddressError )
endif
( pAddr, CCA ) = AddressTranslation( vAddr, DATA, LOAD )
halfwordGPRLEN..0 = LoadMemory( CCA, HALFWORD, pAddr, vAddr, DATA )
GPR[rd]31..0 = sign_extend( halfword15..0 )

Exceptions:

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