DOUBLE PRECISION MULTIPLY MODE
3 - 16
DATA ARITHMETIC LOGIC UNIT
MOTOROLA
3.4
DOUBLE PRECISION MULTIPLY MODE
The Data ALU double precision multiply operation multiplies two 48-bit operands with a
96-bit result. The processor enters the dedicated Double Precision Multiply Mode when
the user sets bit 14 (DM) of the Status Register (bit 6 of the MR register). The mode is
disabled by clearing the DM bit. For information on the DM bit, see Section 5.4.2.13 -
Double Precision Multiply Mode (Bit 14).
CAUTION:
While in the Double Precision Multiply Mode, only the double precision multiply algorithms
shown in Figure 3-11, Figure 3-12, and Figure 3-13 may be executed by the Data ALU;
any other Data ALU operation will give indeterminate results.
Figure 3-11 shows the full double precision multiply algorithm. To allow for pipeline
delay, the ANDI instruction should not be immediately followed by a Data ALU instruc-
tion. For example, the ORI instruction sets the DM mode bit, but, due to the instruction
execution pipeline, the Data ALU enters the Double Precision Multiply mode only after
Y:
X:
R5
MSP2
LSP2
MSP1
LSP1
R1
DP2
DP0
DP3
DP1
R0
R0
DP3_DP2_DP1_DP0 = MSP1_LSP1 x MSP2_LSP2
ori
#$40,mr
;enter mode
move
x:(r1)+,x0
y:(r5)+,y0
;load operands
mpy
y0,x0,a
x:(r1)+,x1
y:(r5)+,y1
;LSP*LSP
➞
a
mac
x1,y0,a
a0,y:(r0)
;shifted(a)+
; MSP*LSP
➞
a
mac
x0,y1,a
;a+LSP*MSP
➞
a
mac
y1,x1,a
a0,x:(r0)+
;shifted(a)+
; MSP*MSP
➞
a
move
a,l:(r0)+
andi
#$bf,mr
;exit mode
non-Data ALU operation
;pipeline delay
Figure 3-11 Full Double Precision Multiply Algorithm
Summary of Contents for DSP56K
Page 12: ...xii LIST of TABLES MOTOROLA List of Tables Continued Table Page Number Title Number ...
Page 13: ...MOTOROLA DSP56K FAMILY INTRODUCTION 1 1 SECTION 1 DSP56K FAMILY INTRODUCTION ...
Page 31: ...MOTOROLA DATA ARITHMETIC LOGIC UNIT 3 1 SECTION 3 DATA ARITHMETIC LOGIC UNIT ...
Page 50: ...DATA ALU SUMMARY 3 20 DATA ARITHMETIC LOGIC UNIT MOTOROLA ...
Page 51: ...MOTOROLA ADDRESS GENERATION UNIT 4 1 SECTION 4 ADDRESS GENERATION UNIT ...
Page 77: ...MOTOROLA PROGRAM CONTROL UNIT 5 1 SECTION 5 PROGRAM CONTROL UNIT ...
Page 124: ...INSTRUCTION GROUPS 6 30 INSTRUCTION SET INTRODUCTION MOTOROLA ...
Page 125: ...MOTOROLA PROCESSING STATES 7 1 SECTION 7 PROCESSING STATES STOP WAIT EXCEPTION NORMAL RESET ...
Page 167: ...STOP PROCESSING STATE MOTOROLA PROCESSING STATES 7 43 ...
Page 168: ...STOP PROCESSING STATE 7 44 PROCESSING STATES MOTOROLA ...
Page 169: ...MOTOROLA PORT A 8 1 SECTION 8 PORT A ...
Page 176: ...PORT A INTERFACE 8 8 PORT A MOTOROLA ...
Page 177: ...MOTOROLA PLL CLOCK OSCILLATOR 9 1 SECTION 9 PLL CLOCK OSCILLATOR x x d Φ VCO ...
Page 191: ...10 2 ON CHIP EMULATION OnCE MOTOROLA SECTION 10 ON CHIP EMULATION OnCE ...
Page 218: ...USING THE OnCE MOTOROLA ON CHIP EMULATION OnCE 10 29 ...
Page 604: ...INSTRUCTION ENCODING A 338 INSTRUCTION SET DETAILS MOTOROLA ...
Page 605: ...MOTOROLA BENCHMARK PROGRAMS B 1 APPENDIX B BENCHMARK PROGRAMS T T T T T P1 P3 P2 P4 T T T ...
Page 609: ...BENCHMARK PROGRAMS MOTOROLA BENCHMARK PROGRAMS B 5 ...
Page 611: ...BENCHMARK PROGRAMS MOTOROLA BENCHMARK PROGRAMS B 7 ...
Page 613: ...BENCHMARK PROGRAMS MOTOROLA BENCHMARK PROGRAMS B 9 ...
Page 615: ...BENCHMARK PROGRAMS MOTOROLA BENCHMARK PROGRAMS B 11 ...