Gpdata_Buffer; Little Endian Vs. Big Endian Byte Order - AVT Pike Technical Manual

Configuration of the camera
GPDATA_INFO

GPDATA_BUFFER

Register Name
0xF1000FFC GPDATA_INFO
0xF1001000
... GPDATA_BUFFER
0xF10017FC
GPDATA_BUFFER
GPDATA_BUFFER is a general purpose register that regulates the exchange of
data between camera and host for:
• writing look-up tables (LUTs) into the camera
• uploading/downloading of the shading image
Buffer size query
indicates the actual storage range
Field
---
BufferSize
Table 163: Advanced register: GPData buffer
Note
• Read the BufferSize before using
• GPDATA_BUFFER can be used by only one function at a
time.

Little endian vs. big endian byte order

• Read/WriteBlock accesses to GPDATA_BUFFER are recommended, to read
or write more than 4 byte data. This increases the transfer speed com-
pared to accessing every single quadlet.
• The big endian byte order of the 1394 bus is unlike the little endian
byte order of common operating systems (Intel PC). Each quadlet of the
local buffer, containing the LUT data or shading image for instance, has
to be swapped bytewise from little endian byte order to big endian byte
order before writing on the bus.
Bit depth little endian
8 bit L0 L1 L2 L3
16 bit L0 H0 L1 H1
Table 164: Swapped first quadlet at address offset 0
Bit Description
[0..15] Reserved
[16..31] Size of GPDATA_BUFFER
(byte)
big endian
L3 L2 L1 L0
H1 L1 H0 L0
PIKE Technical Manual V4.1.0
Description
L: low byte
H: high byte
309