D950-CORE Datasheet, PDF (16/89 Pages) STMicroelectronics – 16-Bit Fixed Point Digital Signal Processor DSP Core

D950-Core
4.1.4 Barrel Shifter Unit (BSU)
The D950-Core BSU provides a complete set of shifting functions
Arithmetic shift: 40-bit input (either a 32 bit operand sign extended to 40-bit, or a 40-bit
accumulator), providing a valid result
8-bit EXT/sign
16-bit MSB
16-bit LSB
Right: shifts the 40-bit input data to the right, the upper part is sign extended
TST
TST
8-bit EXT/sign
16-bit MSB
16-bit LSB
0
Left: shifts the 40-bit input data to the left, the upper part is fed by 0
Logical shift: provides a 32-bit result which is loaded into a 40-bit accumulator, the 8-bit
extension of which is reset.
0
8-bit EXT = 0
16-bit MSB
16-bit LSB
Right: shifts the 32-bit input data to the right, the upper part is fed by 0
TST
TST
8-bit EXT = 0
16-bit MSB
16-bit LSB
0
Left: shifts the 32-bit input data to the left, the upper part is fed by 0
Rotation:
Right: rotates the input data to the right (only through the BSC register)
Left: rotates the 32-bit input data to the left
TS0T
8-bit EXT = 0
16-bit MSB
16-bit LSB
Left with TST: rotates the 33-bit data made of the concatenation of TST-bit
of CCR with the 32-bit input data to the left (the LSB of the 32-bit input is
fed by TST-bit, the MSB of the 32-bit input feeds the TST-bit of CCR).
TST
16-bit MSB
16-bit LSB
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