Shift in pasm i got lost

Anubispod

Hi , i need some help ???

i have a word declared in pasm what reads in the value from a buffer what alternates

the 1 value is 35828 dec 1000_1011_1111_0100 bin
the 2 value is 3060 dec 0000_1011_1111_0100 bin
now where im stuck i need to decode that

from right to left
0-10 are the value 11-14 are the ch number and 15 tells me if it is a repeat frame


rdword decode,t4
mov ch,decode
shl ch,#1
shr ch,#12
wrword ch,t4

now it should schow me 1 in the app but it shows 1 and 17 ???? alternating


Mhh i thought it should kill the bit 15 and then move it over to to the right to get only the chanel number

pik33

  shl ch,#1
  shr ch, #12

does the same as shr ch, #11

What did you try to do doing this shl? Get rid of bit 15? If so, the Propeller is 32 bit and you should try

  shl ch,#17
  shr ch,#28

then you will have bits 11..14 in sh, the rest will be lost.

kwinn

You can shift the data back and forth like you did, or you can mask off the desired bits after shifting them as shown below.

        rdword decode,t4
        mov   ch,decode
        shr   ch,#11            ' shift right to remove value
        and   ch,#%1111     ' mask off channel number
        wrword ch,t4

Anubispod

Ahh tank you ,

i have now a other little problem or question

how would i get now my pointer increased by the channel number i hold in a long not res

i have t4 what points to the start of my array,
then i have my channel number 0-11 in a long

when i try some thing like

add t4,ch*2

does not work ???

pik33

This is assembler, not spin or c, and ch is cog register so you cannot do this in this way. Instead

  mov ch2,ch
  shl ch2,#1
  add t4,ch2

(....)

ch2 res 1

Phil Pilgrim (PhiPi)

Don't forget that, even though you read the value from the hub as a 16-bit word, it exists in the cog register as a 32-bit long. So to shift out bit 15, you have to shift left by 17, not 1.

-Phil

Anubispod

Thanks a lot got it working

Electrodude

Anubispod wrote: »

how would i get now my pointer increased by the channel number i hold in a long not res

A res is a long, using it just saves some hub ram.