serial adder with accumulator verilog code

#Serial adder with accumulator verilog code code
#Serial adder with accumulator verilog code mac

2.3.2 DSP microarchitecture 2.3.2.1 DSP functionality Each action usually requires more than one clock pulse because of the number of steps in an action, even a simple action such as adding.įigure 2.7. The timing of actions is determined by clock pulses which are supplied by a crystal-controlled oscillator, usually at a high speed (as low as 400 MHz for a little notepad computer but close to 3 GHz for a desktop or a fully specified laptop computer). The program must be written so that this sequence is always obeyed. The only difference between a byte of instruction and a byte of data is the way that they are arranged in the memory, instruction first, and its data following, and this correct sequence ensures that the bytes are routed to the correct registers in the microprocessor. The next byte that the microprocessor reads will then be another instruction. When the data has been read the action will be carried out and the result is stored in a register called the accumulator (or it can be stored in memory if another instruction provides for this).

#Serial adder with accumulator verilog code code

The instruction code must contain the information that allows the microprocessor to start a microprogram, then find and read the data (in a register or in the memory).

More usually, one byte will already be stored in a register, usually the accumulator register of the microprocessor, and only one other byte will need to be read from memory. The signals are slightly clipped but are still recognizable as sine waves. The bottom plot shows the result with saturation. The middle plot shows how the result wraps when using the standard two's complement addition. The top plot shows the ideal result, which exceeds the allowable range. In this example, the wave forms are represented as 16-bit integers and are limited to the range −32768 to +32767. Instead of having the calculation results wrapping around at the overflow values, which is standard behavior for two's complement arithmetic, saturation arithmetic operations limit the operation results to the maximum (e.g., +32767 for 16-bit value) or minimum (e.g., −32768 for 16-bit value). To help overcome this problem, the DSP extension of the Cortex-M33 processor supports saturation arithmetic. For example, if we want to utilize the SIMD to maximize processing performance, we cannot do so as the input data values are already restricted to 16 bits (−32768 to +36767 for integer data). In some instances, it is impractical to scale input data to prevent an overflow from happening. If the data processing is carried out in a fixed-point format, the input data values can be scaled accordingly to reduce the chance of an overflow. Thankfully, in most signal processing applications, the input source data values, such as those for audio signals, are only 16–24 bits in size. To avoid the aforementioned issue, an application developer could, therefore, simply restrict the input data value ranges to reduce the chance of the accumulator overflowing. The Cortex-M33 processor does not, however, have a dedicated accumulator register. For example, in some traditional DSPs (e.g., the SHARC processor from Analog Devices), a dedicated accumulator register with a width of 80 bits is available so that this problem does not occur. To solve this problem, many traditional DSPs use a dedicated accumulator register which is wider than the width of the multiplication results.

#Serial adder with accumulator verilog code mac

If the input values for the MAC operation are often close to the limits of the input value range, and there are a high number of elements in the array, the accumulation operations could easily overflow because the multiplication results are 64 bits. In the dot product example in Section 19.3, the input data is 32-bit wide and the accumulator is 64-bit wide. Joseph Yiu, in Definitive Guide to Arm® Cortex®-M23 and Cortex-M33 Processors, 2021 19.5 Dealing with overflows