5-6
SCSI SCRIPTS Instruction Set
Indirect
When set, the 32-bit user data start address for the Block
Move is the address of a pointer to the actual data buffer
address. The value at the 32-bit start address is loaded
into the chip’s
register using
a third Dword fetch (4-byte transfer across the host
computer bus).
Use the fetched byte count, but fetch the data address
from the address in the instruction.
If 64-bit addressing is desired, the upper Dword of the
address is stored in the
register. When the value in SBMS is 0x0, 32-bit
addressing is assumed.
Once the data pointer address is loaded, it is executed
as when the chip operates in the direct mode. This
indirect feature allows specification of a table of data
buffer addresses. Using the SCSI SCRIPTS compiler, the
table offset is placed in the SCRIPT at compile time.
Then at the actual data transfer time, the offsets are
added to the base address of the data address table by
the external processor. The logical I/O driver builds a
structure of addresses for an I/O rather than treating each
address individually.
Note:
Using indirect and table indirect addressing simultaneously
is not permitted; use only one addressing method at a time.
TIA
Table Indirect
28
32-Bit Addressing
When this bit is set, the 24-bit signed value in the start
address of the move is treated as a relative displacement
from the value in the
register. Both the transfer count and the source/
destination address are fetched from this location.
Use the signed integer offset in bits [23:0] of the second
four bytes of the instruction, added to the value in the
register, to fetch first the
byte count and then the data address. The signed value
Command
Byte Count
Address of Pointer to Data
Содержание LSI53C1000
Страница 6: ...vi Preface...
Страница 16: ...xvi Contents...
Страница 28: ...1 12 Introduction...
Страница 234: ...4 124 Registers...
Страница 314: ...6 40 Specifications This page intentionally left blank...
Страница 318: ...6 44 Specifications This page intentionally left blank...
Страница 344: ...6 70 Specifications This page intentionally left blank...
Страница 350: ...6 76 Specifications Figure 6 42 LSI53C1000 329 Ball Grid Array Bottom view...
Страница 352: ...6 78 Specifications...
Страница 360: ...A 8 Register Summary...
Страница 376: ...IX 12 Index...