Topic       : MC68030 - Instruction Assembler Syntax
Author      : Bjørn Ove Årthun/Jiri Kucik
Version     : mc68030.hyp 0.01 (29/02/96)
Subject     : Programming/Others
Nodes       : 120
Index Size  : 2440
HCP-Version : 2
Compiled on : Atari
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View Ref-FileNAME      BFEXTU -- Bit field unsigned extract"

SYNOPSIS  BFEXTU  <ea>{OFFSET:WIDTH},Dn  (68020+)

          No size specs.

FUNCTION  <ea> indicates source operand which a part of bits have to be
          extracted and extended. Offset enables to locate first bit of field;
          width specifies number of bits of this field. Field is extracted,
          and extended to 32 bits by zero. Result is stored in the data
          register Dn.
          Be careful, this instruction operates from MSB to LSB!!

FORMAT                                                      <ea>
          +---------------------------------------========================+
          |15 |14 |13 |12 |11 |10 | 9 | 8 | 7 | 6 | 5 | 4 | 3 | 2 | 1 | 0 |
          |---|---|---|---|---|---|---|---|---|---|-----------|-----------|
          | 1 | 1 | 1 | 0 | 1 | 0 | 0 | 1 | 1 | 1 |    MODE   | REGISTER  |
          |---|-----------|---|-------------------|-----------------------|
          | 0 |  REGISTER |Do |       OFFSET      |Dw |      WIDTH        |
          +---------------------------------------------------------------+

          If Do = 0->Field "OFFSET" contains an immediate value which represents
          effective offset, value from 0 to 31.
          If Do = 1->Field "OFFSET" indicates number of a data register (bits 9
          and 10 of field cleared) which contains effective offset. Signed value
          is represented on 32 bits., so it's extended from -2 EXP 31 to
          (+2 EXP 31) -1.

          If Dw = 0->field "WIDTH" contains an immediate value between 1 and 31
          which indicates a width from 1 to 31 bits. A value of 0 indicates a
          width of 32 bits.
          If Dw = 1->field "WIDTH" indicates number of a data register (bits 3
          and 4 of field cleared) which contains width of bit field. The value
          modulo 32 can go from 1 to 31, indicating a width from 1 to 31 bits.
          A value 0 indicates a width of 32 bits.

REGISTER  <ea> specifies destination, addressing modes are the following:
          +-------------------------------+ +-----------------------------+
          |Addressing Mode|Mode| Register | |Addressing Mode|Mode|Register|
          |-------------------------------| |-----------------------------|
          |      Dn       |000 |Nã reg. Dn| |    Abs.W      |111 |  000   |
          |-------------------------------| |-----------------------------|
          |      An       | -  |     -    | |    Abs.L      |111 |  001   |
          |-------------------------------| |-----------------------------|
          |     (An)      |010 |Nã reg. An| |   (d16,PC)    |111 |  010   |
          |-------------------------------| |-----------------------------|
          |     (An)+     | -  |     -    | |   (d8,PC,Xi)  |111 |  011   |
          |-------------------------------| |-----------------------------|
          |    -(An)      | -  |     -    | |   (bd,PC,Xi)  |111 |  011   |
          |-------------------------------| |-----------------------------|
          |    (d16,An)   |101 |Nã reg. An| |([bd,PC,Xi],od)|111 |  011   |
          |-------------------------------| |-----------------------------|
          |   (d8,An,Xi)  |110 |Nã reg. An| |([bd,PC],Xi,od)|111 |  011   |
          |-------------------------------| |-----------------------------|
          |   (bd,An,Xi)  |110 |Nã reg. An| |    #data      | -  |   -    |
          |-------------------------------| +-----------------------------+
          |([bd,An,Xi]od) |110 |Nã reg. An|
          |-------------------------------|
          |([bd,An],Xi,od)|110 |Nã reg. An|
          +-------------------------------+

RESULT    X - not affected
          N - Set if MSB of field is set. Cleared otherwise.
          Z - Set if all the bits of the field tested are zero.
              Cleared otherwise.
          V - Always cleared.
          C - Always cleared.