Hi Andres,
On Thu, Sep 02, 2010 at 09:35:22PM +0200, Andres Vahter wrote:
> horner_mul_int.s43
>
> ;******************************************************************************
> ; MSP430FG439 Integer-Integer multiplication using Horner's Algorithm
> ;
> ; Description: This code performs a 16-bit integer-integer multplication
> ; of numbers to return an 16-bit integer
> ;
> ;
> ; Note: This code assumes 32.768kHz XTAL on LFXT1 on the MSP430FG439
> ; MSP430FG439
> ; -----------------
> ; | XIN|-
> ; | | 32.768kHz
> ; | XOUT|-
> ; | |
> ;
> ;
> ; K. Venkat
> ; Texas Instruments Inc.
> ; July 2006
> ; Built with IAR Embedded Workbench Version: 3.41A
> ;*******************************************************************************/
> public mul_horner_int
>
> RSEG CODE
>
> mul_horner_int
>
> mov.w R12,R13 ; The operand "input" in register
> R12
> rla.w R13
> add.w R12,R13 ; X1=X*2^1+X
> rla.w R13
> rla.w R13
> add.w R12,R13 ; X2=X1*2^2+X
> rla.w R13
> add.w R12,R13 ; X3=X2*2^1+X
> rla.w R13
> add.w R12,R13 ; X4=X4*2^1+X
> rla.w R13
> rla.w R13
> rla.w R13
> add.w R12,R13 ; Final Result=X5=X4*2^3+X
> mov.w R13,R12 ; The final answer returned to
> the
> ; calling function
> ret
> END
The binary representation of the number 441 is embedded in the code from left
to right.
441 = 110111001b
Something like the following pseudo-code:
for each binary digit d do:
if d == 1
mov.w R12,R13
rla.w R13
else
rla.w R13
end
baruch
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