(maxima.info)Functions and Variables for bitwise

---

Prev: Top Up: Top

---

Enter node , (file) or (file)node

43.1 Functions and Variables for bitwise
========================================

 -- Function: bit_not (<int>)

     Inverts all bits of a signed integer.  The result of this action
     reads '-int - 1'.

          (%i1) load("bitwise")$
          (%i2) bit_not(i);
          (%o2)                      bit_not(i)
          (%i3) bit_not(bit_not(i));
          (%o3)                           i
          (%i4) bit_not(3);
          (%o4)                          - 4
          (%i5) bit_not(100);
          (%o5)                         - 101
          (%i6) bit_not(-101);
          (%o6)                          100

 -- Function: bit_and (<int1>, ...)

     This function calculates a bitwise 'and' of two or more signed
     integers.

          (%i1) load("bitwise")$
          (%i2) bit_and(i,i);
          (%o2)                           i
          (%i3) bit_and(i,i,i);
          (%o3)                           i
          (%i4) bit_and(1,3);
          (%o4)                           1
          (%i5) bit_and(-7,7);
          (%o5)                           1

     If it is known if one of the parameters to 'bit_and' is even this
     information is taken into consideration by the function.
          (%i1) load("bitwise")$
          (%i2) declare(e,even,o,odd);
          (%o2)                         done
          (%i3) bit_and(1,e);
          (%o3)                           0
          (%i4) bit_and(1,o);
          (%o4)                           1

 -- Function: bit_or (<int1>, ...)

     This function calculates a bitwise 'or' of two or more signed
     integers.

          (%i1) load("bitwise")$
          (%i2) bit_or(i,i);
          (%o2)                           i
          (%i3) bit_or(i,i,i);
          (%o3)                           i
          (%i4) bit_or(1,3);
          (%o4)                           3
          (%i5) bit_or(-7,7);
          (%o5)                          - 1

     If it is known if one of the parameters to 'bit_or' is even this
     information is taken into consideration by the function.
          (%i1) load("bitwise")$
          (%i2) declare(e,even,o,odd);
          (%o2)                         done
          (%i3) bit_or(1,e);
          (%o3)                         e + 1
          (%i4) bit_or(1,o);
          (%o4)                           o

 -- Function: bit_xor (<int1>, ...)

     This function calculates a bitwise 'or' of two or more signed
     integers.

          (%i1) load("bitwise")$
          (%i2) bit_xor(i,i);
          (%o2)                           0
          (%i3) bit_xor(i,i,i);
          (%o3)                           i
          (%i4) bit_xor(1,3);
          (%o4)                           2
          (%i5) bit_xor(-7,7);
          (%o5)                          - 2

     If it is known if one of the parameters to 'bit_xor' is even this
     information is taken into consideration by the function.
          (%i1) load("bitwise")$
          (%i2) declare(e,even,o,odd);
          (%o2)                         done
          (%i3) bit_xor(1,e);
          (%o3)                         e + 1
          (%i4) bit_xor(1,o);
          (%o4)                         o - 1

 -- Function: bit_lsh (<int>, <nBits>)

     This function shifts all bits of the signed integer 'int' to the
     left by 'nBits' bits.  The width of the integer is extended by
     'nBits' for this process.  The result of 'bit_lsh' therefore is
     'int * 2'.

          (%i1) load("bitwise")$
          (%i2) bit_lsh(0,1);
          (%o2)                           0
          (%i3) bit_lsh(1,0);
          (%o3)                           1
          (%i4) bit_lsh(1,1);
          (%o4)                           2
          (%i5) bit_lsh(1,i);
          (%o5)                     bit_lsh(1, i)
          (%i6) bit_lsh(-3,1);
          (%o6)                          - 6
          (%i7) bit_lsh(-2,1);
          (%o7)                          - 4

 -- Function: bit_rsh (<int>, <nBits>)

     This function shifts all bits of the signed integer 'int' to the
     right by 'nBits' bits.  The width of the integer is reduced by
     'nBits' for this process.

          (%i1) load("bitwise")$
          (%i2) bit_rsh(0,1);
          (%o2)                           0
          (%i3) bit_rsh(2,0);
          (%o3)                           2
          (%i4) bit_rsh(2,1);
          (%o4)                           1
          (%i5) bit_rsh(2,2);
          (%o5)                           0
          (%i6) bit_rsh(-3,1);
          (%o6)                          - 2
          (%i7) bit_rsh(-2,1);
          (%o7)                          - 1
          (%i8) bit_rsh(-2,2);
          (%o8)                          - 1

 -- Function: bit_length (<int>)

     determines how many bits a variable needs to be long in order to
     store the number 'int'.  This function only operates on positive
     numbers.

          (%i1) load("bitwise")$
          (%i2) bit_length(0);
          (%o2)                           0
          (%i3) bit_length(1);
          (%o3)                           1
          (%i4) bit_length(7);
          (%o4)                           3
          (%i5) bit_length(8);
          (%o5)                           4

 -- Function: bit_onep (<int>, <nBit>)

     determines if bits 'nBit' is set in the signed integer 'int'.

          (%i1) load("bitwise")$
          (%i2) bit_onep(85,0);
          (%o2)                         true
          (%i3) bit_onep(85,1);
          (%o3)                         false
          (%i4) bit_onep(85,2);
          (%o4)                         true
          (%i5) bit_onep(85,3);
          (%o5)                         false
          (%i6) bit_onep(85,100);
          (%o6)                         false
          (%i7) bit_onep(i,100);
          (%o7)                   bit_onep(i, 100)

     For signed numbers the sign bit is interpreted to be more than
     'nBit' to the left of the leftmost bit of 'int' that reads '1'.
          (%i1) load("bitwise")$
          (%i2) bit_onep(-2,0);
          (%o2)                         false
          (%i3) bit_onep(-2,1);
          (%o3)                         true
          (%i4) bit_onep(-2,2);
          (%o4)                         true
          (%i5) bit_onep(-2,3);
          (%o5)                         true
          (%i6) bit_onep(-2,4);
          (%o6)                         true

     If it is known if the number to be tested is even this information
     is taken into consideration by the function.
          (%i1) load("bitwise")$
          (%i2) declare(e,even,o,odd);
          (%o2)                         done
          (%i3) bit_onep(e,0);
          (%o3)                         false
          (%i4) bit_onep(o,0);
          (%o4)                         true