Analog Devices ADSP-21020

ADSP-21020

REV. C –9–

Table III. Universal Registers

Name Function

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