Texas Instruments MSP430x1xx - Manual (Page 95)

Hardware Multiplier Operation
6-7
Hardware Multiplier
6.2.3 Multiply Unsigned and Accumulate, 16x16bit, 16x8bit, 8x16bit, 8x8bit
The following multiplication operation shows 32 bytes of program code and 32
execution cycles (16X16-bit multiplication).
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*
TRANSFER BOTH OPERANDS TO THE REGISTERS IN THE *
* HARDWARE MULTIPLIER MODULE *
* THE RESULT OF THE MULTIPLICATION IS ADDED TO THE *
* CONTENT OF BOTH RESULT REGISTERS, RESLO AND RESHI *
* USE CONSTANT OPERAND1 AND OPERAND2 TO IDENTIFY *
* BYTE DATA *
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OPERAND1 .EQU 0 ; 0: OPERAND1 IS WORD (16BIT)
; 8: OPERAND1 IS BYTE ( 8BIT)
OPERAND2 .EQU 0 ; 0: OPERAND2 IS WORD (16BIT)
; 8: OPERAND2 IS BYTE ( 8BIT)
MPY .EQU 0130H
MPYS .EQU 0132H
MAC .EQU 0134H
MACS .EQU 0136H
OP2 .EQU 0138H
RESLO .EQU 013AH
RESHI .EQU 013CH
SUMEXT .EQU 013EH
.BSS OPER1,2,200H
.BSS OPER2,2
.BSS RAM,8
.IF OPERAND1=8
MOV.B
&OPER1,&MAC ; LOAD 1ST OPERAND,
; DEFINES ADD. UNSIGNED MULTIPLY
.ELSE
MOV
&OPER1,&MAC ; LOAD 1ST OPERAND,
; DEFINES ADD. UNSIGNED MULTIPLY
.ENDIF
.IF OPERAND1=8
MOV.B
&OPER2,&OP2 ; LOAD 2ND OPERAND AND START
; MULTIPLICATION
.ELSE
MOV
&OPER2,&OP2 ; LOAD 2ND OPERAND AND START
; MULTIPLICATION
.ENDIF
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*
EXAMPLE TO ADD THE RESULT OF THE HARDWARE *
* MULTIPLICATION TO THE RAM DATA, 64BITS *
* THE RESULT OF THE MULTIPLICATION IS HELD IN RESLO*
* AND RESHI REGISTERS. THE UPPER TWO WORDS IN THE *
* EXAMPLE ARE FURTHER LOCATED IN THEIR RAM LOCATION*
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ADDC &SUMEXT,&RAM+4 ; ADD SUMEXTENSTION TO RAM+4
ADC &RAM+6 ; IF 64 BIT LENGTH IS USED