Field offset contiguous data allocation – Interphase Tech CONDOR 4221 User Manual
Page 66
Chapter 3 - MACSI Host Interface
54
Field Offset
The value in the far left column specifies the field offset. This value measures increments of 16 bits from the
beginning of the record, and may be thought of as the displacement to be added to a pointer to short integer
data type required to differentiate the particular field.
This construct is indicated by the term Offst appearing in the table heading, and is used for objects that may
appear in different locations, either in host system memory or the Short I/O space.
Contiguous Data Allocation
Finally, contiguous allocated space may be specified with a starting address and an ending address, as follows:
For addresses, the final number will always represent the last byte address of the allocated space. For offsets,
it represents the final offset location, as follows:
Onboard Command Queue Entry
Offst
15
14
13
12
11
10
9
8
7
6
5
4
3
2
1
0
0x00
Queue Entry Control Register
0x01
Reserved
Command Response Block
Addr
15
14
13
12
11
10
9
8
7
6
5
4
3
2
1
0
0x73A
to
0x73E
Reserved
(8 Bytes)
Initialize Controller
Offst
15
14
13
12
11
10
9
8
7
6
5
4
3
2
1
0
0x07
Controller Initialization Block Offset
0x08
to
0x11
Reserved
(20 Bytes)