include builtins\VM\pFPU.e  -- :%down53 etc

function safe_add(atom a, atom b)
atom low,high
    -- NB: be sure to restore the usual/default rounding!
    #ilASM{
        [32]
            lea esi,[a]
            call :%pLoadFlt
            lea esi,[b]
            call :%pLoadFlt
            fld st0
            call :%down53
            fadd st0,st2
            lea edi,[low]
            call :%pStoreFlt
            call :%up53
            faddp
            lea edi,[high]
            call :%pStoreFlt
            call :%near53       -- usual/default
        [64]
            lea rsi,[a]
            call :%pLoadFlt
            lea rsi,[b]
            call :%pLoadFlt
            fld st0
            call :%down64
            fadd st0,st2
            lea rdi,[low]
            call :%pStoreFlt
            call :%up64
            faddp
            lea rdi,[high]
            call :%pStoreFlt
            call :%near64   -- usual/default
        []
          }
    return {low,high}
end function

constant nums = {{1, 2},
                 {0.1, 0.2},
                 {1e100, 1e-100},
                 {1e308, 1e308}}

    for i=1 to length(nums) do
        atom {a,b} = nums[i]
        atom {low,high} = safe_add(a,b)
        printf(1,"%.16g + %.16g =\n", {a, b});
        printf(1,"    [%.16g, %.16g]\n", {low, high});
        printf(1,"    size %.16g\n\n", high - low);
    end for