2-12 SC140 DSP Core Reference Manual
DALU
2.2.1.3 Bit-Field Unit (BFU)
The BFU i s th e log i c p a rt of the ALU. It co nta in s a 40-bit parallel bidirectional shifter (with a 40-bit input
and a 40-bit output) mask generation unit and logic unit. The BFU is used in the following operations:
•Multi-bit left/right shift (arithmetic or logical)
•One-bit rotate (right or left)
•Bit-field insert and extract
•Count leading bits (ones or zeros)
•Logical operations
•Sign or zero extension operations
Table 2-6 lists the instructions which are executed in the BFU. A more detailed description of each
instruction is given in Appendix A, “SC140 DSP Core Instruction Set.”
NEG Negate
RND Round
SAT.F Saturate fractional value in data register to fit in high portion
SAT.L Saturate value in data register to fit in 32 bits
SBC Subtract long with carry
SBR Subtract and round
SUB Subtract
SUB2 Subtract two words
SUBL Shift left and subtract
SUBNC.W Subtract with no carry bit generation
TFR Transfer data register to a data register
TFRF Transfer data register to a data register if T bit is false
TFRT Transfer data register to a data register if T bit is true
TSTEQ Test for equal to zero
TSTEQ.L 32-bit compare for equal to zero
TSTGE Test for greater than or equal to zero
TSTGT Test for greater than zero
Table 2-5. DALU Arithmetic Instructions (MAC) (Continued)
Instruction Description