Guppy PRO Technical Manual
V4.1.2
243
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
compared to accessing every single quadlet.
•
The big endian byte order of the 1394 bus is unlike the little endian byte
order of common Intel PCs. Each quadlet of the local buffer, containing
the LUT data for instance, has to be swapped bytewise from little endian
byte order to big endian byte order before writing on the bus.
Note
•
Read the BufferSize before using.
•
GPDATA_BUFFER can be used by only one function at a
time.
Bit depth
little endian
big 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 151: Swapped first quadlet at address offset 0
