Select Bit A (Sba[4:0])—Csfs Bits 4–0; Select Register A (Sra[1:0])—Csfs Bits 6–5; Select Bit B (Sbb[4:0])—Csfs Bits 12–8; Select Register B (Srb[1:0])—Csfs Bits 14–13 - Motorola DSP56305 User Manual

and C), each determining one bit in the address. The subregisters are divided into three
parts: a bit select (5 bits, abbreviated SBxx), a register select (2 bits, abbreviated SRxx),
and a reserved bit (without name). The CSFS bits are shown in Figure 14-5 and are
described in the following paragraphs.
11 10
SBB3 SBB2 SBB1 SBB0
23 22
SRC1 SRC0 SBC4 SBC3 SBC2 SBC1 SBC0
Reserved bit, Read as zero, should be written with zero for future compatibility
14.4.3.1.1 Select Bit A (SBA[4:0])—CSFS Bits 4–0
The Select Bit A (SBA[4:0]) bits determine which bit (0 to 23) in a particular CFSR is
selected as the first (LSB) address line of the Step Function Table. Which CFSR is used is
determined by bits SRA[1:0] in CSFS. The values 24 to 31 are invalid and should not be
used.
14.4.3.1.2 Select Register A (SRA[1:0])—CSFS Bits 6–5
The Select Register A (SRA[1:0]) bits select which CFSR from which the selected bit (by
SBA[4:0]) is connected to the first (LSB) address line of the Step Function Table. The
combination of SBA[4:0] and SRA[1:0] determine which bit of which CFSR is used as the
first address line of the Step Function Table.
14.4.3.1.3 Select Bit B (SBB[4:0])—CSFS Bits 12–8
The Select Bit B (SBB[4:0]) bits determine which bit (0 to 23) in a particular CFSR is
selected as the second (middle byte) address line of the Step Function Table. Which
CFSR is used is determined by bits SRB[1:0] in CSFS. The values 24 to 31 are invalid and
should not be used.
14.4.3.1.4 Select Register B (SRB[1:0])—CSFS Bits 14–13
The Select Register B (SRB[1:0]) bits select which CFSR from which the selected bit (by
SBB[4:0]) is connected to the second (middle byte) address line of the Step Function
Table. The combination of SBB[4:0] and SRB[1:0] determine which bit of which CFSR is
used as the second address line of the Step Function Table.
MOTOROLA
9 8 7
SRA1 SRA0 SBA4 SBA3 SBA2 SBA1 SBA0
21 20 19

Figure 14-5 Step Function Select Register (CSFS)

DSP56305 User's Manual
CYCLIC CODE CO-PROCESSOR
6 5 4 3
18 17 16 15
CCOP Programming Model
2 1 0
14 13 12
SRB1 SRB0 SBB4
AA1304
14-11