i need VHDL code for stair case waveform

Multisim has expanded its circuit simulation capabilities and enhanced the engineer's toolbox with a large set of custom instruments and analyzes, developed in LabVIEW and now available for download to Multisim users. Using the rich set of mathematical functions, programming algorithms, and measurement tools in LabVIEW, engineers actually have a unique set of capabilities that can redefine how SPICE can be used for circuit design. Connecting the digital circuits to the sensor devices is simple if the sensor devices are inherently digital. Switches, relays and encoders are easily connected to door circuits due to the on / off nature of their signals. However, when it comes to analogue devices, the interconnection becomes much more complex. What is needed is a way to electronically translate analog signals into digital (binary) quantities, and vice versa. An analog-to-digital converter, or ADC, performs the above task while a digital-to-analog converter, or DAC, performs the latter. An ADC enters an electrical analog signal such as voltage or current and outputs a binary number.