Saturate on Overflow - 2025.2 English

Saturate on Overflow - 2025.2 English - UG1483

Vitis Model Composer User Guide (UG1483)

Document ID

UG1483

Release Date

2025-11-20

Version

2025.2 English

Saturate on Integer Overflow

Vitis Model Composer supports overflow detection of integer data values on signals. As previously indicated, the default overflow mechanism is to wrap on overflow. Specific blocks in the standard Simulink library of blocks and in the HLS library have an option to Saturate on integer overflow. You can enable this on the Block Parameters dialog box. This parameter applies only if the output is an integer (int8, int16, int32, uint8, uint16, uint32).

Refer to the Model Composer Block Library for block-specific information.

Figure 1. Saturate on Integer Overflow

Saturate on integer overflow means the output stays at the maximum or minimum supported value when the input exceeds the valid range. The value is saturated, and does not change.

Saturate on Fixed-Point Overflow

For fixed-point data types (on the DTC for example), overflow modes offer more control than the Saturate on integer overflow option. See the following figure for reference.

Figure 2. Fixed-Point Overflow

The following table describes the different fixed-point overflow modes. Graphs illustrate the conditions.

Table 1. Fixed-Point Overflow Modes
Mode	Description	Image
Saturation	When the input value overflows the output data type, the output value reaches saturation at the min or max value, and does not change.
Saturation to Zero	When the input value overflows the output data type, the output value reaches saturation at the min or max value, and returns to zero.
Symmetrical Saturation	Like Saturation to Zero, except the min and max values are symmetrical, or equal in size though opposite in value.
Wrap around	When the input value exceeds the output data type, the output value is wrapped from the maximum value to the minimum value, or from the minimum value to the maximum value, thus cycling through the range of permitted values.
Sign-Magnitude Wrap Around	When the input value exceeds the output data type, the output value reaches the maximum value, and then begins decreasing to return to the minimum value. In an underflow situation, the minimum value is reached, and begins increasing to return to the maximum value.