Analog Devices ADSP-21020 - Manual (Page 9)

ADSP-21020
REV. C –9–
Table III. Universal Registers
Name Function
Register File
R15–R0
Register file locations
Program Sequencer
PC*
Program counter; address of instruction cur-
rently executing
PCSTK Top of PC stack
PCSTKP PC stack pointer
FADDR* Fetch address
DADDR* Decode address
LADDR Loop termination address, code; top of loop
address stack
CURLCNTR Current loop counter; top of loop count stack
LCNTR Loop count for next nested counter-controlled
loop
Data Address Generators
I7–I0
DAG1 index registers
M7–M0 DAG1 modify registers
L7–L0 DAG1 length registers
B7–B0 DAG1 base registers
I15–I8 DAG2 index registers
M15–M8 DAG2 modify registers
L15–L8 DAG2 length registers
B15–B8 DAG2 base registers
Bus Exchange
PX1
PMD-DMD bus exchange 1 (16 bits)
PX2 PMD-DMD bus exchange 2 (32 bits)
PX 48-bit PX1 and PX2 combination
Timer
TPERIOD
Timer period
TCOUNT Timer counter
Memory Interface
DMWAIT
Wait state and page size control for data
memory
DMBANK1 Data memory bank 1 upper boundary
DMBANK2 Data memory bank 2 upper boundary
DMBANK3 Data memory bank 3 upper boundary
DMADR* Copy of last data memory address
PMWAIT Wait state and page size control for program
memory
PMBANK1 Program memory bank 1 upper boundary
PMADR* Copy of last program memory address
System Registers
MODE1
Mode control bits for bit-reverse, alternate reg-
isters, interrupt nesting and enable, ALU satu-
ration, floating-point rounding mode and
boundary
MODE2 Mode control bits for interrupt sensitivity,
cache disable and freeze, timer enable, and I/O
flag configuration
IRPTL Interrupt latch
IMASK Interrupt mask
IMASKP Interrupt mask pointer (for nesting)
ASTAT Arithmetic status flags, bit test, I/O flag values,
and compare accumulator
STKY Sticky arithmetic status flags, circular buffer
overflow flags, stack status flags (not sticky)
USTAT1 User status register l
USTAT2 User status register 2
*read-only
Refer to User’s Manual for bit-level definitions of each register.
Table IV. ALU Compute Operations
Fixed-Point Floating-Point
Rn = Rx + Ry Fn = Fx + Fy
Rn = Rx – Ry Fn = Fx – Fy
Rn = Rx + Ry, Rm = Rx – Ry Fn = Fx + Fy, Fm = Fx – Fy
Rn = Rx + Ry + CI Fn = ABS (Fx + Fy)
Rn = Rx – Ry + CI – l Fn = ABS (Fx – Fy)
Rn = (Rx + Ry)/2 Fn = (Fx + Fy)/2
COMP(Rx, Ry) COMP(Fx, Fy)
Rn = –Rx Fn = –Fx
Rn = ABS Rx Fn = ABS Fx
Rn = PASS Rx Fn = PASS Fx
Rn = MIN(Rx, Ry) Fn = MIN(Fx, Fy)
Rn = MAX(Rx, Ry) Fn = MAX(Fx, Fy)
Rn = CLIP Rx BY Ry Fn = CLIP Fx BY Fy
Rn = Rx + CI Fn = RND Fx
Rn = Rx + CI – 1 Fn = SCALB Fx BY Ry
Rn = Rx + l Rn = MANT Fx
Rn = Rx – l Rn = LOGB Fx
Rn = Rx AND Ry Rn = FIX Fx BY Ry
Rn = Rx OR Ry Rn = FIX Fx
Rn = Rx XOR Ry Fn = FLOAT Rx BY Ry
Rn = NOT Rx Fn = FLOAT Rx
Fn = RECIPS Fx
Fn = RSQRTS Fx
Fn = Fx COPYSIGN Fy
Rn, Rx, Ry R15–R0; register file location, fixed-point
Fn, Fx, Fy F15–F0; register file location, floating point