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Gpdata_buffer, Little endian vs. big endian byte order, R in chapter – ALLIED Vision Technologies Stingray F-504 User Manual

Page 342: E chapter, Table 169: advanced register: gpdata buffer

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Configuration of the camera

STINGRAY Technical Manual V4.4.4

340

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

GPDATA_INFO

Buffer size query

GPDATA_BUFFER

indicates the actual storage range

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.

Register

Name

Field

Bit

Description

0xF1000FFC GPDATA_INFO

---

[0..15]

Reserved

BufferSize

[16..31]

Size of GPDATA_BUFFER
(byte)

0xF1001000

0xF10017FC

GPDATA_BUFFER

Table 169: Advanced register: GPData buffer

Note

Read the BufferSize before using.

GPDATA_BUFFER can be used by only one function at a
time.

Bit depth

little endianbig endian

Description

8 bit

L0 L1 L2 L3  L3 L2 L1 L0

L: low byte

H: high byte

16 bit

L0 H0 L1 H1  H1 L1 H0 L0

Table 170: Swapped first quadlet at address offset 0