Encoding:

Format:

LBUX rd, index(base)

LBUX rd, rs(rt)

Purpose:

Load Unsigned Byte Indexed

To load a byte from memory as an unsigned 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 8bit byte at the memory location specified by the aligned effective address are fetched, zero-extended to the GPR register length and placed in GPR rd.

Restrictions:

None.

Operation:

ValidateAccessToDSPResources()
vAddr31..0 = GPR[index]31..0 + GPR[base]31..0
( pAddr, CCA ) = AddressTranslation( vAddr, DATA, LOAD )
pAddr = pAddrPSIZE-1..2 || ( pAddr1..0 xor ReverseEndian2 )
memwordGPRLEN..0 = LoadMemory ( CCA, BYTE, pAddr, vAddr, DATA )
GPR[rd]31..0 = zero_extend( memword7..0 )

Exceptions:

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