OpenEuphoria

1. how to shift bits in memory

• Posted by gareth_mcdaid Jan 24, 2011
• 1325 views

Hi everyone

I need to know how to shift bits in memory, I’m using version 3.1 of euphoria.

I’ve look in the manual for a inbuilt function to shift bits around in memory, but not been able to find one.

Do I need to write my own?

include misc.e 
include machine.e 
 
--The pic12f675  
 
puts(1,"  pic12f675  \n") 
 
 
constant rom_size    = 1024 --each opcode is incoded with 14 bits. 
                            --wraping is used because the program counter 
                            --is able to address upto 8kb 
 
constant ram_size    = 256  --the ram is 256 bytes it is split into two banks 
                            --each bank is 128 bytes. 
                            --the general purpose ram is mapped across both banks 
                            --and starts at location 20h-5fh or 32-96 
 
--constant eeprom_size = 128 
 
atom rom 
atom ram 
sequence stack 
 
integer pc   -- program counter 
integer regw -- working registery 
integer bank -- selected bank 
 
 
 
 
procedure init() 
 
  pc   = 0 
  regw = 0 
  bank = 0 
 
  stack={} 
  
  rom = allocate(rom_size*2) 
  ram = allocate(ram_size) 
 
end procedure 
 
 
procedure deinit() 
  free(rom) 
  free(ram) 
end procedure 
 
 
procedure reset() 
  free(rom) 
  free(ram) 
 
  rom = allocate(rom_size*2) 
  ram = allocate(ram_size) 
 
  pc   = 0 
  regw = 0 
  bank = 0 
 
  stack= {} 
   
end procedure  
 
 
procedure loadcart() 
  integer fn,char,pos 
  fn = open("data.bin","rb") 
 
  for i=0 to 63 do 
    char=getc(fn) 
    poke(ram+32+i , char) 
  end for 
 
  pos=0 
  for i=0 to (rom_size/2)-1 do 
    char=getc(fn) 
    poke(rom+pos,char) 
    char=getc(fn) 
    poke(rom+pos+1,char) 
    pos+=2 
  end for 
 
 
  close(fn) 
end procedure 
 
function peek2(atom address) 
  return peek(address)*256 + peek(address+1) 
end function 
 
 
integer instr 
integer optype 
integer opcode 
 
procedure execute_op() 
 
  --?peek(rom) 
  --?peek(rom+1) 
  instr = peek2(rom+pc) 
 
   
  instr = and_bits(instr,#3FFF) -- trim of the 2 msbits  
   
  optype = and_bits(instr,#3000) 
 
 
   
  ?instr 
  ?optype 
   
   
  if optype=0 then      
    -- BYTE-ORIENTED FILE REGISTER OPERATIONS 
 
    opcode = and_bits(instr,#F00) 
 
    if opcode=8 then 
      puts(1,"movf\n") 
    end if 
 
    ?opcode 
 
  elsif optype=1 then   
    -- BIT-ORIENTED FILE REGISTER OPERATIONS 
 
  else 
    -- LITERAL AND CONTROL OPERATIONS 
 
  end if   
 
 
  pc+=2 
end procedure 
 
 
init() 
loadcart() 
execute_op() 
 
 
sleep(1) 
 
 
 

3. Re: how to shift bits in memory

• Posted by mattlewis (admin) Jan 24, 2011
• 1301 views

You might try Bit Operations by Juergen Luethje.

Matt

5. Re: how to shift bits in memory

• Posted by unkmar Jan 29, 2011
• 1206 views

I don't know what all is in that zip file.
I do know that bit-shifts are nothing more than multiply or of integers of powers of 2 in euphoria.
These are not bit rotations. The left does not rotate to the right.

integer test = 6 -- 8-bits of binary 00000110 
test *= 2 -- left bit shift by 1, 00001100 
test *= 4 -- left bit shift by 2, 00110000 
test /= power(2, 3) -- power(2,3) = 8, right bit shift by 3, 00000011 
test /= 2 -- right bit shift by 1, 00000001