EXTRACTBITS

Block Screenshot

Contents

• Description
• Data types
• Parameters
• Default properties
• Interfacing function
• Computational function
• Example
• See also

Description

For an integer input this block outputs a contiguous selection of bits. The operation can be summarized by this expression:

Output = Input ∧ Mask

i.e. a bitwise AND between Input and Mask an integer of the same length as input with the bits to extract set to 1 and the other bits set to 0. Bits to Extract parameter defines the method by which the user selects the output bits as summarized by the following table with index 0, as that of the least significant bit :

The output value depends also on the forth parameter Treat Bit Field as an Integer :

• 0 : the output is directly the result of extraction.

• 1 : the output is the integer conversion of the extraction result according to the signed or non-signed status of the input.

Data types

The block supports the following types :

• Input : scalar. All Scilab's integer type (Data Type parameter).

• Output : same type than input.

Parameters

• Data Type (3:int32, 4:int16, 5:int8, ...)

  It indicates the integer type on input: Between 3 and 8.

  Properties : Type 'vec' of size 1.

• Bits to Extract

  It indicates the mode used to extract bits from the input data : Between 1 and 5 (1:Upper Half, 2:Lower Half, 3:Range from MSB, 4:Range to LSB, 5:Range of bits)

  Properties : Type 'vec' of size 1.

• Number of Bits or Index of Bit

  When the Bits to Extract field is set to :

  • 1 or 2, this parameter is ignored.

  • 3 or 4, this parameter is used to determine the number of bits to extract. This number must be if the type is :

    • int32 or uint32: positive and less than 32.

    • int16 or uint16: positive and less than 16.

    • int8 or uint8: positive and less than 8.

  • 5, this parameter is used to determine range of bits to extract and it must have the [Start, End] form vector. Start must be less than End. These values must be, if the type is:

    • int32 or uint32: positive and less than 32.

    • int16 or uint16: positive and less than 16.

    • int8 or uint8: positive and less than 8.

  See description for more information

  Properties : Type 'vec' of size -1.

• Treat Bit Field as an Integer (0:No, 1:Yes)

  0 or 1. It indicates the scaling mode to use on the output bits selection. See description for more explanation.

  Properties : Type 'vec' of size 1.

Default properties

• always active: no

• direct-feedthrough: yes

• zero-crossing: no

• mode: no

• regular inputs:

  - port 1 : size [1,1] / type 3

• regular outputs:

  - port 1 : size [1,1] / type 3

• number/sizes of activation inputs: 0

• number/sizes of activation outputs: 0

• continuous-time state: no

• discrete-time state: no

• object discrete-time state: no

• name of computational function: extract_bit_32_UH0

Example

In the following table, we present the results obtained for the number 215 according to several combinations of the parameters.

In the following diagram, two decimal digit numbers are coded on an only byte. The diagram decode the input to obtain two separate digits.

Interfacing function

• SCI/modules/scicos_blocks/macros/IntegerOp/EXTRACTBITS.sci

Computational function

• SCI/modules/scicos_blocks/src/c/extract_bit_32_UH0.c
• SCI/modules/scicos_blocks/src/c/extract_bit_32_UH1.c
• SCI/modules/scicos_blocks/src/c/extract_bit_u32_UH1.c
• SCI/modules/scicos_blocks/src/c/extract_bit_32_LH.c
• SCI/modules/scicos_blocks/src/c/extract_bit_32_MSB0.c
• SCI/modules/scicos_blocks/src/c/extract_bit_32_MSB1.c
• SCI/modules/scicos_blocks/src/c/extract_bit_u32_MSB1.c
• SCI/modules/scicos_blocks/src/c/extract_bit_32_LSB.c
• SCI/modules/scicos_blocks/src/c/extract_bit_32_RB0.c
• SCI/modules/scicos_blocks/src/c/extract_bit_32_RB1.c
• SCI/modules/scicos_blocks/src/c/extract_bit_u32_RB1.c
• SCI/modules/scicos_blocks/src/c/extract_bit_16_UH0.c
• SCI/modules/scicos_blocks/src/c/extract_bit_16_UH1.c
• SCI/modules/scicos_blocks/src/c/extract_bit_u16_UH1.c
• SCI/modules/scicos_blocks/src/c/extract_bit_16_LH.c
• SCI/modules/scicos_blocks/src/c/extract_bit_16_MSB0.c
• SCI/modules/scicos_blocks/src/c/extract_bit_16_MSB1.c
• SCI/modules/scicos_blocks/src/c/extract_bit_u16_MSB1.c
• SCI/modules/scicos_blocks/src/c/extract_bit_16_LSB.c
• SCI/modules/scicos_blocks/src/c/extract_bit_16_RB0.c
• SCI/modules/scicos_blocks/src/c/extract_bit_16_RB1.c
• SCI/modules/scicos_blocks/src/c/extract_bit_u16_RB1.c
• SCI/modules/scicos_blocks/src/c/extract_bit_8_UH0.c
• SCI/modules/scicos_blocks/src/c/extract_bit_8_UH1.c
• SCI/modules/scicos_blocks/src/c/extract_bit_u8_UH1.c
• SCI/modules/scicos_blocks/src/c/extract_bit_8_LH.c
• SCI/modules/scicos_blocks/src/c/extract_bit_8_MSB0.c
• SCI/modules/scicos_blocks/src/c/extract_bit_8_MSB1.c
• SCI/modules/scicos_blocks/src/c/extract_bit_u8_MSB1.c
• SCI/modules/scicos_blocks/src/c/extract_bit_8_LSB.c
• SCI/modules/scicos_blocks/src/c/extract_bit_8_RB0.c
• SCI/modules/scicos_blocks/src/c/extract_bit_8_RB1.c
• SCI/modules/scicos_blocks/src/c/extract_bit_u8_RB1.c

See also

• BITSET — Set a Bit
• BITCLEAR — Clear a Bit
• LOGICAL_OP — 論理演算子