562 lines
11 KiB
V
562 lines
11 KiB
V
/*
|
|
|
|
atof util
|
|
|
|
Copyright (c) 2019 Dario Deledda. All rights reserved.
|
|
Use of this source code is governed by an MIT license
|
|
that can be found in the LICENSE file.
|
|
|
|
This file contains utilities for convert a string in a f64 variable
|
|
IEEE 754 standard is used
|
|
|
|
Know limitation:
|
|
- limited to 18 significant digits
|
|
|
|
The code is inspired by:
|
|
Grzegorz Kraszewski krashan@teleinfo.pb.edu.pl
|
|
URL: http://krashan.ppa.pl/articles/stringtofloat/
|
|
Original license: MIT
|
|
|
|
*/
|
|
module strconv
|
|
|
|
union Float64u {
|
|
mut:
|
|
f f64
|
|
u u64
|
|
}
|
|
|
|
/*
|
|
|
|
96 bit operation utilities
|
|
Note: when u128 will be available these function can be refactored
|
|
|
|
*/
|
|
|
|
// right logical shift 96 bit
|
|
fn lsr96(s2 u32, s1 u32, s0 u32) (u32,u32,u32) {
|
|
mut r0 := u32(0)
|
|
mut r1 := u32(0)
|
|
mut r2 := u32(0)
|
|
r0 = (s0>>1) | ((s1 & u32(1))<<31)
|
|
r1 = (s1>>1) | ((s2 & u32(1))<<31)
|
|
r2 = s2>>1
|
|
return r2,r1,r0
|
|
}
|
|
|
|
// left logical shift 96 bit
|
|
fn lsl96(s2 u32, s1 u32, s0 u32) (u32,u32,u32) {
|
|
mut r0 := u32(0)
|
|
mut r1 := u32(0)
|
|
mut r2 := u32(0)
|
|
r2 = (s2<<1) | ((s1 & (u32(1)<<31))>>31)
|
|
r1 = (s1<<1) | ((s0 & (u32(1)<<31))>>31)
|
|
r0 = s0<<1
|
|
return r2,r1,r0
|
|
}
|
|
|
|
// sum on 96 bit
|
|
fn add96(s2 u32, s1 u32, s0 u32, d2 u32, d1 u32, d0 u32) (u32,u32,u32) {
|
|
mut w := u64(0)
|
|
mut r0 := u32(0)
|
|
mut r1 := u32(0)
|
|
mut r2 := u32(0)
|
|
w = u64(s0) + u64(d0)
|
|
r0 = u32(w)
|
|
w >>= 32
|
|
w += u64(s1) + u64(d1)
|
|
r1 = u32(w)
|
|
w >>= 32
|
|
w += u64(s2) + u64(d2)
|
|
r2 = u32(w)
|
|
return r2,r1,r0
|
|
}
|
|
|
|
// subtraction on 96 bit
|
|
fn sub96(s2 u32, s1 u32, s0 u32, d2 u32, d1 u32, d0 u32) (u32,u32,u32) {
|
|
mut w := u64(0)
|
|
mut r0 := u32(0)
|
|
mut r1 := u32(0)
|
|
mut r2 := u32(0)
|
|
w = u64(s0) - u64(d0)
|
|
r0 = u32(w)
|
|
w >>= 32
|
|
w += u64(s1) - u64(d1)
|
|
r1 = u32(w)
|
|
w >>= 32
|
|
w += u64(s2) - u64(d2)
|
|
r2 = u32(w)
|
|
return r2,r1,r0
|
|
}
|
|
|
|
/*
|
|
|
|
Constants
|
|
|
|
*/
|
|
|
|
|
|
const (
|
|
//
|
|
// f64 constants
|
|
//
|
|
digits = 18
|
|
double_plus_zero = u64(0x0000000000000000)
|
|
double_minus_zero = u64(0x8000000000000000)
|
|
double_plus_infinity = u64(0x7FF0000000000000)
|
|
double_minus_infinity = u64(0xFFF0000000000000)
|
|
//
|
|
// parser state machine states
|
|
//
|
|
fsm_a = 0
|
|
fsm_b = 1
|
|
fsm_c = 2
|
|
fsm_d = 3
|
|
fsm_e = 4
|
|
fsm_f = 5
|
|
fsm_g = 6
|
|
fsm_h = 7
|
|
fsm_i = 8
|
|
fsm_stop = 9
|
|
//
|
|
// Possible parser return values.
|
|
//
|
|
parser_ok = 0 // parser finished OK
|
|
parser_pzero = 1 // no digits or number is smaller than +-2^-1022
|
|
parser_mzero = 2 // number is negative, module smaller
|
|
parser_pinf = 3 // number is higher than +HUGE_VAL
|
|
parser_minf = 4 // number is lower than -HUGE_VAL
|
|
//
|
|
// char constants
|
|
// Note: Modify these if working with non-ASCII encoding
|
|
//
|
|
c_dpoint = `.`
|
|
c_plus = `+`
|
|
c_minus = `-`
|
|
c_zero = `0`
|
|
c_nine = `9`
|
|
c_ten = u32(10)
|
|
)
|
|
/*
|
|
|
|
Utility
|
|
|
|
*/
|
|
|
|
// NOTE: Modify these if working with non-ASCII encoding
|
|
fn is_digit(x byte) bool {
|
|
return (x >= c_zero && x <= c_nine) == true
|
|
}
|
|
|
|
fn is_space(x byte) bool {
|
|
return (x == `\t` || x == `\n` || x == `\v` || x == `\f` || x == `\r` || x == ` `)
|
|
}
|
|
|
|
fn is_exp(x byte) bool {
|
|
return (x == `E` || x == `e`) == true
|
|
}
|
|
|
|
/*
|
|
|
|
Support struct
|
|
|
|
*/
|
|
|
|
// The structure is filled by parser, then given to converter.
|
|
pub struct PrepNumber {
|
|
pub mut:
|
|
negative bool // 0 if positive number, 1 if negative
|
|
exponent int // power of 10 exponent
|
|
mantissa u64 // integer mantissa
|
|
}
|
|
/*
|
|
|
|
String parser
|
|
NOTE: #TOFIX need one char after the last char of the number
|
|
|
|
*/
|
|
|
|
// parser return a support struct with all the parsing information for the converter
|
|
fn parser(s string) (int,PrepNumber) {
|
|
mut state := fsm_a
|
|
mut digx := 0
|
|
mut c := byte(` `) // initial value for kicking off the state machine
|
|
mut result := parser_ok
|
|
mut expneg := false
|
|
mut expexp := 0
|
|
mut i := 0
|
|
mut pn := PrepNumber{
|
|
}
|
|
for state != fsm_stop {
|
|
match state {
|
|
// skip starting spaces
|
|
fsm_a {
|
|
if is_space(c) == true {
|
|
c = s[i]
|
|
i++
|
|
}
|
|
else {
|
|
state = fsm_b
|
|
}
|
|
}
|
|
// check for the sign or point
|
|
fsm_b {
|
|
state = fsm_c
|
|
if c == c_plus {
|
|
c = s[i]
|
|
i++
|
|
}
|
|
else if c == c_minus {
|
|
pn.negative = true
|
|
c = s[i]
|
|
i++
|
|
}
|
|
else if is_digit(c) {
|
|
}
|
|
else if c == c_dpoint {
|
|
}
|
|
else {
|
|
state = fsm_stop
|
|
}
|
|
}
|
|
// skip the inital zeros
|
|
fsm_c {
|
|
if c == c_zero {
|
|
c = s[i++]
|
|
}
|
|
else if c == c_dpoint {
|
|
c = s[i++]
|
|
state = fsm_d
|
|
}
|
|
else {
|
|
state = fsm_e
|
|
}
|
|
}
|
|
// reading leading zeros in the fractional part of mantissa
|
|
fsm_d {
|
|
if c == c_zero {
|
|
c = s[i++]
|
|
if pn.exponent > -2147483647 {
|
|
pn.exponent--
|
|
}
|
|
}
|
|
else {
|
|
state = fsm_f
|
|
}
|
|
}
|
|
// reading integer part of mantissa
|
|
fsm_e {
|
|
if is_digit(c) {
|
|
if digx < digits {
|
|
pn.mantissa *= 10
|
|
pn.mantissa += u64(c - c_zero)
|
|
digx++
|
|
}
|
|
else if pn.exponent < 2147483647 {
|
|
pn.exponent++
|
|
}
|
|
c = s[i++]
|
|
}
|
|
else if c == c_dpoint {
|
|
c = s[i++]
|
|
state = fsm_f
|
|
}
|
|
else {
|
|
state = fsm_f
|
|
}
|
|
}
|
|
// reading fractional part of mantissa
|
|
fsm_f {
|
|
if is_digit(c) {
|
|
if digx < digits {
|
|
pn.mantissa *= 10
|
|
pn.mantissa += u64(c - c_zero)
|
|
pn.exponent--
|
|
digx++
|
|
}
|
|
c = s[i++]
|
|
}
|
|
else if is_exp(c) {
|
|
c = s[i++]
|
|
state = fsm_g
|
|
}
|
|
else {
|
|
state = fsm_g
|
|
}
|
|
}
|
|
// reading sign of exponent
|
|
fsm_g {
|
|
if c == c_plus {
|
|
c = s[i++]
|
|
}
|
|
else if c == c_minus {
|
|
expneg = true
|
|
c = s[i++]
|
|
}
|
|
state = fsm_h
|
|
}
|
|
// skipping leading zeros of exponent
|
|
fsm_h {
|
|
if c == c_zero {
|
|
c = s[i++]
|
|
}
|
|
else {
|
|
state = fsm_i
|
|
}
|
|
}
|
|
// reading exponent digits
|
|
fsm_i {
|
|
if is_digit(c) {
|
|
if expexp < 214748364 {
|
|
expexp *= 10
|
|
expexp += int(c - c_zero)
|
|
}
|
|
c = s[i++]
|
|
}
|
|
else {
|
|
state = fsm_stop
|
|
}
|
|
}
|
|
else {
|
|
}}
|
|
// C.printf("len: %d i: %d str: %s \n",s.len,i,s[..i])
|
|
if i >= s.len {
|
|
state = fsm_stop
|
|
}
|
|
}
|
|
if expneg {
|
|
expexp = -expexp
|
|
}
|
|
pn.exponent += expexp
|
|
if pn.mantissa == 0 {
|
|
if pn.negative {
|
|
result = parser_mzero
|
|
}
|
|
else {
|
|
result = parser_pzero
|
|
}
|
|
}
|
|
else if pn.exponent > 309 {
|
|
if pn.negative {
|
|
result = parser_minf
|
|
}
|
|
else {
|
|
result = parser_pinf
|
|
}
|
|
}
|
|
else if pn.exponent < -328 {
|
|
if pn.negative {
|
|
result = parser_mzero
|
|
}
|
|
else {
|
|
result = parser_pzero
|
|
}
|
|
}
|
|
return result,pn
|
|
}
|
|
|
|
/*
|
|
|
|
Converter to the bit form of the f64 number
|
|
|
|
*/
|
|
|
|
// converter return a u64 with the bit image of the f64 number
|
|
fn converter(mut pn PrepNumber) u64 {
|
|
mut binexp := 92
|
|
mut s2 := u32(0) // 96-bit precision integer
|
|
mut s1 := u32(0)
|
|
mut s0 := u32(0)
|
|
mut q2 := u32(0) // 96-bit precision integer
|
|
mut q1 := u32(0)
|
|
mut q0 := u32(0)
|
|
mut r2 := u32(0) // 96-bit precision integer
|
|
mut r1 := u32(0)
|
|
mut r0 := u32(0)
|
|
mask28 := u32(0xF<<28)
|
|
mut result := u64(0)
|
|
// working on 3 u32 to have 96 bit precision
|
|
s0 = u32(pn.mantissa & u64(0x00000000FFFFFFFF))
|
|
s1 = u32(pn.mantissa>>32)
|
|
s2 = u32(0)
|
|
// so we take the decimal exponent off
|
|
for pn.exponent > 0 {
|
|
q2,q1,q0 = lsl96(s2, s1, s0) // q = s * 2
|
|
r2,r1,r0 = lsl96(q2, q1, q0) // r = s * 4 <=> q * 2
|
|
s2,s1,s0 = lsl96(r2, r1, r0) // s = s * 8 <=> r * 2
|
|
s2,s1,s0 = add96(s2, s1, s0, q2, q1, q0) // s = (s * 8) + (s * 2) <=> s*10
|
|
pn.exponent--
|
|
for (s2 & mask28) != 0 {
|
|
q2,q1,q0 = lsr96(s2, s1, s0)
|
|
binexp++
|
|
s2 = q2
|
|
s1 = q1
|
|
s0 = q0
|
|
}
|
|
}
|
|
for pn.exponent < 0 {
|
|
for !((s2 & (u32(1)<<31)) != 0) {
|
|
q2,q1,q0 = lsl96(s2, s1, s0)
|
|
binexp--
|
|
s2 = q2
|
|
s1 = q1
|
|
s0 = q0
|
|
}
|
|
q2 = s2 / c_ten
|
|
r1 = s2 % c_ten
|
|
r2 = (s1>>8) | (r1<<24)
|
|
q1 = r2 / c_ten
|
|
r1 = r2 % c_ten
|
|
r2 = ((s1 & u32(0xFF))<<16) | (s0>>16) | (r1<<24)
|
|
r0 = r2 / c_ten
|
|
r1 = r2 % c_ten
|
|
q1 = (q1<<8) | ((r0 & u32(0x00FF0000))>>16)
|
|
q0 = r0<<16
|
|
r2 = (s0 & u32(0xFFFF)) | (r1<<16)
|
|
q0 |= r2 / c_ten
|
|
s2 = q2
|
|
s1 = q1
|
|
s0 = q0
|
|
pn.exponent++
|
|
}
|
|
// C.printf("mantissa before normalization: %08x%08x%08x binexp: %d \n", s2,s1,s0,binexp)
|
|
// normalization, the 28 bit in s2 must the leftest one in the variable
|
|
if s2 != 0 || s1 != 0 || s0 != 0 {
|
|
for (s2 & mask28) == 0 {
|
|
q2,q1,q0 = lsl96(s2, s1, s0)
|
|
binexp--
|
|
s2 = q2
|
|
s1 = q1
|
|
s0 = q0
|
|
}
|
|
}
|
|
// rounding if needed
|
|
/*
|
|
* "round half to even" algorithm
|
|
* Example for f32, just a reminder
|
|
*
|
|
* If bit 54 is 0, round down
|
|
* If bit 54 is 1
|
|
* If any bit beyond bit 54 is 1, round up
|
|
* If all bits beyond bit 54 are 0 (meaning the number is halfway between two floating-point numbers)
|
|
* If bit 53 is 0, round down
|
|
* If bit 53 is 1, round up
|
|
*/
|
|
/* test case 1 complete
|
|
s2=0x1FFFFFFF
|
|
s1=0xFFFFFF80
|
|
s0=0x0
|
|
*/
|
|
|
|
/* test case 1 check_round_bit
|
|
s2=0x18888888
|
|
s1=0x88888880
|
|
s0=0x0
|
|
*/
|
|
|
|
/* test case check_round_bit + normalization
|
|
s2=0x18888888
|
|
s1=0x88888F80
|
|
s0=0x0
|
|
*/
|
|
|
|
// C.printf("mantissa before rounding: %08x%08x%08x binexp: %d \n", s2,s1,s0,binexp)
|
|
// s1 => 0xFFFFFFxx only F are rapresented
|
|
nbit := 7
|
|
check_round_bit := u32(1)<<u32(nbit)
|
|
check_round_mask := u32(0xFFFFFFFF)<<u32(nbit)
|
|
if (s1 & check_round_bit) != 0 {
|
|
// C.printf("need round!! cehck mask: %08x\n", s1 & ~check_round_mask )
|
|
if (s1 & ~check_round_mask) != 0 {
|
|
// C.printf("Add 1!\n")
|
|
s2,s1,s0 = add96(s2, s1, s0, 0, check_round_bit, 0)
|
|
}
|
|
else {
|
|
// C.printf("All 0!\n")
|
|
if (s1 & (check_round_bit<<u32(1))) != 0 {
|
|
// C.printf("Add 1 form -1 bit control!\n")
|
|
s2,s1,s0 = add96(s2, s1, s0, 0, check_round_bit, 0)
|
|
}
|
|
}
|
|
s1 = s1 & check_round_mask
|
|
s0 = u32(0)
|
|
// recheck normalization
|
|
if s2 & (mask28<<u32(1)) != 0 {
|
|
// C.printf("Renormalize!!")
|
|
q2,q1,q0 = lsr96(s2, s1, s0)
|
|
binexp--
|
|
s2 = q2
|
|
s1 = q1
|
|
s0 = q0
|
|
}
|
|
}
|
|
// tmp := ( u64(s2 & ~mask28) << 24) | ((u64(s1) + u64(128)) >> 8)
|
|
// C.printf("mantissa after rounding : %08x%08x%08x binexp: %d \n", s2,s1,s0,binexp)
|
|
// C.printf("Tmp result: %016x\n",tmp)
|
|
// end rounding
|
|
// offset the binary exponent IEEE 754
|
|
binexp += 1023
|
|
if binexp > 2046 {
|
|
if pn.negative {
|
|
result = double_minus_infinity
|
|
}
|
|
else {
|
|
result = double_plus_infinity
|
|
}
|
|
}
|
|
else if binexp < 1 {
|
|
if pn.negative {
|
|
result = double_minus_zero
|
|
}
|
|
else {
|
|
result = double_plus_zero
|
|
}
|
|
}
|
|
else if s2 != 0 {
|
|
mut q := u64(0)
|
|
binexs2 := u64(binexp)<<52
|
|
q = (u64(s2 & ~mask28)<<24) | ((u64(s1) + u64(128))>>8) | binexs2
|
|
if pn.negative {
|
|
q |= (u64(1)<<63)
|
|
}
|
|
result = q
|
|
}
|
|
return result
|
|
}
|
|
|
|
/*
|
|
|
|
Public functions
|
|
|
|
*/
|
|
|
|
// atof64 return a f64 from a string doing a parsing operation
|
|
pub fn atof64(s string) f64 {
|
|
mut pn := PrepNumber{
|
|
}
|
|
mut res_parsing := 0
|
|
mut res := Float64u{}
|
|
|
|
res_parsing,pn = parser(s + ' ') // TODO: need an extra char for now
|
|
// println(pn)
|
|
match res_parsing {
|
|
parser_ok {
|
|
res.u = converter(mut pn)
|
|
}
|
|
parser_pzero {
|
|
res.u = double_plus_zero
|
|
}
|
|
parser_mzero {
|
|
res.u = double_minus_zero
|
|
}
|
|
parser_pinf {
|
|
res.u = double_plus_infinity
|
|
}
|
|
parser_minf {
|
|
res.u = double_minus_infinity
|
|
}
|
|
else {
|
|
}}
|
|
return res.f
|
|
}
|