Merging 2 rows into key=value string with BusyBox

Question

I need to write an sh script for embedded linux, which only has BusyBox (v1.30.1). I can use "sh", "awk", or "sed".

I have a script which receives 2 variables:

columns="usr sys nic idle io irq sirq"
points="2.2 4.5 0.0 93.1 0.0 0.0 0.0"

Both variables can have arbitrary number of measurements (from 1 to ~15).

I need to combine them to get a 3'd variable:

payload="usr=2.2, sys=4.5, nic=0.0, idle=93.1, io=0.0, irq=0.0, sirq=0.0"

Sh doesn't support arrays, so I can't iterate through "columns" and "points". Is there any way to achieve this task inside sh script (ideally) or with external commands available in BusyBox?

Edit: added what I tried as per James Brown request (obviously it didn't work as sh doesn't support arrays):

for index in ${!columns[*]}; do 
  payload="${payload} ${columns[$index]}=${points[$index]}"
done

Answer 1

Using Busybox awk:

$ payload=$(busybox awk -v c="$columns" -v p="$points" '
BEGIN {
    n=split(c,cc)
    m=split(p,pp)
    if(m==n)
        for(i=1;i<=n;i++)
            printf "%s=%s%s",cc[i],pp[i],(i==n?ORS:", ")
}')
$ echo $payload
usr=2.2 sys=4.5 nic=0.0 idle=93.1 io=0.0 irq=0.0 sirq=0.0