Sun Microelectronics
231
13. UltraSPARC Extended Instructions
Description:
Block load and store instructions are selected by using one of the block transfer
ASIs with the LDDA and STDA instructions. These ASIs allow block loads or
stores to be performed to the same address spaces as normal loads and stores.
Little-endian ASIs access data in little-endian format, otherwise the access is as-
sumed to be big-endian. The byte swapping is performed separately for each of
the eight double-precision registers used by the instruction. Endianness does not
matter if these instructions are being used for block copy.
Block stores with commit force the data to be written to memory and invalidate
copies in all caches, if present. As a result, block commit stores maintain coheren-
cy with the I-Cache unlike other stores. They do not, however, flush instructions
that have already been fetched into the pipeline. Execute a FLUSH, DONE, or RE-
TRY instruction to flush the pipeline before executing the modified code.
LDDA with a block transfer ASI loads 64 bytes of data from a 64-byte aligned
memory area into eight double-precision floating-point registers specified by
freg
rd
. The lowest addressed eight bytes in memory are loaded into the lowest
numbered double-precision rd register. An
illegal_instruction
trap is taken if the
floating-point registers are not aligned on an eight-double-precision register
boundary. The least significant 6 bits of the address must be zero or a
mem_address_not_aligned
trap is taken.
STDA with a block transfer ASI stores data from eight double-precision floating-
point registers specified by rs1 to a 64 byte aligned memory area. The lowest ad-
dressed eight bytes in memory are stored from the lowest numbered double pre-
cision freg. An
illegal_instruction
trap is taken if the floating-point registers are not
aligned on an eight register boundary. The least significant 6 bits of the address
must be zero, or a
mem_address_not_aligned
trap is taken.
Traps:
fp_disabled
illegal_instruction (
nonaligned rd. Not checked if opcode is not LDFA or STDFA
)
data_access_exception
mem_address_not_aligned
(Checked for opcode implied alignment if the
opcode is not LDFA or STDFA)
PA_watchpoint
VA_watchpoint
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