Managing Overflow - 2024.1 English

Vitis Model Composer User Guide (UG1483)

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2024.1 English

Sometimes the data type definition for a block will not support the incoming data value on a signal. In these cases, an overflow condition can occur if the value on the signal is too large or too small to be represented by the data type of the block. The two types of overflow that can occur are wrap overflow, and saturation overflow:

Wrap on Overflow
This is the default overflow mechanism, and causes the bit value to wrap at the overflow point. For instance, when an arithmetic operation such as multiplying two numbers produces a result larger than the maximum value for the data type, effectively causing a wrap around.
Saturate on Overflow
This is an overflow mechanism in which all operations such as addition and multiplication are limited to a fixed range between the minimum and maximum values supported by the data type. In essence, the value will reach the maximum or minimum value and stop.

Wrapping is the default method for handling overflow, as it occurs naturally as the value overruns the data type. There is no checking required. However, the Saturate on Overflow option requires some additional logic in order to check the data value against the permitted maximum or minimum value to prevent wrapping. This additional logic consumes available resources on the target device.