PYNQ-Z2 floating point conversions

division.cpp

void divide (float a, float b, float *c)
{
#pragma HLS interface s_axilite port=a
#pragma HLS interface s_axilite port=b
#pragma HLS interface s_axilite port=c
#pragma HLS interface ap_ctrl_none port=return
	*c = a / b;
}

division_tb.cpp

#include <iostream>
using namespace std;

void divide(float a, float b, float *c);

int main()
{
	float a = 42.0f;
	float b = 3.0f;
	float c;

	divide(a, b, &c);

	std:cout << c << std::endl;

	return 0;
}

pynq_float.py

import struct

"""
Please note that these functions only work
for single number input and output
"""

def float_to_bytes(a: float) -> bytes:
    return struct.pack("f", a)

  
def bytes_to_float(a: int) -> float:
    return struct.unpack("f", struct.pack("i", a))[0]
  

usage_example.py

from pynq import Overlay
from pynq import MMIO

import struct


def float_to_bytes(a: float) -> bytes:
    return struct.pack("f", a)

  
def bytes_to_float(a: int) -> float:
    return struct.unpack("f", struct.pack("i", a))[0]

  
divide_overlay = Overlay("../../overlays/divide_test/divide_test.bit")
divide_overlay.download()

# Divide 42.9 by 3.0, resulting in 14.3
divide_mmio = MMIO(0x43C0_0000, 0x10000)

divide_mmio.write(0x10, float_to_bytes(42.9));
divide_mmio.write(0x18, float_to_bytes(3.0));

print(bytes_to_float(divide_mmio.read(0x20)))