Expressions Involving ap_[u]fixed<> types - 2024.1 English

Vitis High-Level Synthesis User Guide (UG1399)

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2024.1 English

Arbitrary precision fixed-point values can participate in expressions that use any operators supported by C/C++. After an arbitrary precision fixed-point type or variable is defined, their usage is the same as for any floating point type or variable in the C/C++ languages.

Observe the following caveats:

  • Zero and Sign Extensions

    All values of smaller bit-width are zero or sign-extended depending on the sign of the source value. You may need to insert casts to obtain alternative signs when assigning smaller bit-widths to larger.

  • Truncations

    Truncation occurs when you assign an arbitrary precision fixed-point of larger bit-width than the destination variable.