gen_speed_limit_entries.py

import math
import numpy as np

INT_MAX = 2147483647

def double_to_dec(db):
    """Convert a float to its decimal representation used by the P4 switch and the forkproxy. """

    # return (long) ( Integer.MAX_VALUE/(16*4*Math.PI) * d);
    return int(INT_MAX/(16*4*math.pi) * db)

def int_to_binstr(n):
    """Convert a 64-bit integer to a binary literal form used by the P4 language."""

    return "0b"+np.binary_repr(n,width=64)

def get_lpm_p(d):
    """Get lpm limit rules for the given positive limit."""

    bs = int_to_binstr(double_to_dec(d))[2:]
    ps = []
    prefix = "0"
    for i in range(1,len(bs)):
        if bs[i]=="0":
            ps.append(prefix+"1")
        prefix = prefix + bs[i]
    return [ ( p+(64-len(p))*'0' , len(p) ) for p in ps ]

def get_lpm_n(d):
    """Get lpm limit rules for the given negative limit."""

    bs = int_to_binstr(double_to_dec(d))[2:]
    ps = []
    prefix = "1"
    for i in range(1,len(bs)):
        if bs[i]=="1":
            ps.append(prefix+"0")
        prefix = prefix + bs[i]
    return [ ( p+(64-len(p))*'0' , len(p) ) for p in ps ]

def get_lpm(d):
    """Get the lpm limit rules."""

    if d>=0:
        return get_lpm_p(d)
    else:
        return get_lpm_n(d)
    
def print_lpm_p4(joint_id,d):
    """Print the lpm rules of the given limit according to the P4 syntax."""

    for bits, mask in get_lpm(d):
        print("(",joint_id,",",'0b'+bits,"&&&", hex(int('1'*mask+'0'*(64-mask),2)),") :","override_speed(",int_to_binstr(double_to_dec(d)),");")

print("// AUTOGENERATED FILE. Do not edit manually!\n")

JOINT_SPEED_LIMITS = [3.5,3.5,3.5,3.5,3.5,3.5]

for i in range(6):
    print("// JOINT",i+1,"SPEED LIMIT:",JOINT_SPEED_LIMITS[i])
    print_lpm_p4(i,JOINT_SPEED_LIMITS[i])
    print_lpm_p4(i,-1*JOINT_SPEED_LIMITS[i])
    print()