mirror of
https://github.com/vlang/v.git
synced 2023-08-10 21:13:21 +03:00
341 lines
6.7 KiB
V
341 lines
6.7 KiB
V
module strconv
|
||
|
||
/*
|
||
|
||
f32/f64 to string utilities
|
||
|
||
Copyright (c) 2019-2021 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 the f32/f64 to string utilities functions
|
||
|
||
These functions are based on the work of:
|
||
Publication:PLDI 2018: Proceedings of the 39th ACM SIGPLAN
|
||
Conference on Programming Language Design and ImplementationJune 2018
|
||
Pages 270–282 https://doi.org/10.1145/3192366.3192369
|
||
|
||
inspired by the Go version here:
|
||
https://github.com/cespare/ryu/tree/ba56a33f39e3bbbfa409095d0f9ae168a595feea
|
||
|
||
*/
|
||
|
||
import math.bits
|
||
|
||
//import math
|
||
|
||
/*
|
||
|
||
General Utilities
|
||
|
||
*/
|
||
fn assert1(t bool, msg string) {
|
||
if !t {
|
||
panic(msg)
|
||
}
|
||
}
|
||
|
||
[inline]
|
||
fn bool_to_int(b bool) int {
|
||
if b {
|
||
return 1
|
||
}
|
||
return 0
|
||
}
|
||
|
||
[inline]
|
||
fn bool_to_u32(b bool) u32 {
|
||
if b {
|
||
return u32(1)
|
||
}
|
||
return u32(0)
|
||
}
|
||
|
||
[inline]
|
||
fn bool_to_u64(b bool) u64 {
|
||
if b {
|
||
return u64(1)
|
||
}
|
||
return u64(0)
|
||
}
|
||
|
||
fn get_string_special(neg bool, expZero bool, mantZero bool) string {
|
||
if !mantZero {
|
||
return "nan"
|
||
}
|
||
if !expZero {
|
||
if neg {
|
||
return "-inf"
|
||
} else {
|
||
return "+inf"
|
||
}
|
||
}
|
||
if neg {
|
||
return "-0e+00"
|
||
}
|
||
return "0e+00"
|
||
}
|
||
|
||
/*
|
||
|
||
32 bit functions
|
||
|
||
*/
|
||
fn decimal_len_32(u u32) int {
|
||
// Function precondition: u is not a 10-digit number.
|
||
// (9 digits are sufficient for round-tripping.)
|
||
// This benchmarked faster than the log2 approach used for u64.
|
||
assert1(u < 1000000000, "too big")
|
||
|
||
if u >= 100000000 { return 9 }
|
||
else if u >= 10000000 { return 8 }
|
||
else if u >= 1000000 { return 7 }
|
||
else if u >= 100000 { return 6 }
|
||
else if u >= 10000 { return 5 }
|
||
else if u >= 1000 { return 4 }
|
||
else if u >= 100 { return 3 }
|
||
else if u >= 10 { return 2 }
|
||
return 1
|
||
}
|
||
|
||
fn mul_shift_32(m u32, mul u64, ishift int) u32 {
|
||
// QTODO
|
||
//assert ishift > 32
|
||
|
||
hi, lo := bits.mul_64(u64(m), mul)
|
||
shifted_sum := (lo >> u64(ishift)) + (hi << u64(64-ishift))
|
||
assert1(shifted_sum <= 2147483647, "shiftedSum <= math.max_u32")
|
||
return u32(shifted_sum)
|
||
}
|
||
|
||
fn mul_pow5_invdiv_pow2(m u32, q u32, j int) u32 {
|
||
return mul_shift_32(m, pow5_inv_split_32[q], j)
|
||
}
|
||
|
||
fn mul_pow5_div_pow2(m u32, i u32, j int) u32 {
|
||
return mul_shift_32(m, pow5_split_32[i], j)
|
||
}
|
||
|
||
fn pow5_factor_32(i_v u32) u32 {
|
||
mut v := i_v
|
||
for n := u32(0); ; n++ {
|
||
q := v/5
|
||
r := v%5
|
||
if r != 0 {
|
||
return n
|
||
}
|
||
v = q
|
||
}
|
||
return v
|
||
}
|
||
|
||
// multiple_of_power_of_five_32 reports whether v is divisible by 5^p.
|
||
fn multiple_of_power_of_five_32(v u32, p u32) bool {
|
||
return pow5_factor_32(v) >= p
|
||
}
|
||
|
||
// multiple_of_power_of_two_32 reports whether v is divisible by 2^p.
|
||
fn multiple_of_power_of_two_32(v u32, p u32) bool {
|
||
return u32(bits.trailing_zeros_32(v)) >= p
|
||
}
|
||
|
||
// log10_pow2 returns floor(log_10(2^e)).
|
||
fn log10_pow2(e int) u32 {
|
||
// The first value this approximation fails for is 2^1651
|
||
// which is just greater than 10^297.
|
||
assert1(e >= 0, "e >= 0")
|
||
assert1(e <= 1650, "e <= 1650")
|
||
return (u32(e) * 78913) >> 18
|
||
}
|
||
|
||
// log10_pow5 returns floor(log_10(5^e)).
|
||
fn log10_pow5(e int) u32 {
|
||
// The first value this approximation fails for is 5^2621
|
||
// which is just greater than 10^1832.
|
||
assert1(e >= 0, "e >= 0")
|
||
assert1(e <= 2620, "e <= 2620")
|
||
return (u32(e) * 732923) >> 20
|
||
}
|
||
|
||
// pow5_bits returns ceil(log_2(5^e)), or else 1 if e==0.
|
||
fn pow5_bits(e int) int {
|
||
// This approximation works up to the point that the multiplication
|
||
// overflows at e = 3529. If the multiplication were done in 64 bits,
|
||
// it would fail at 5^4004 which is just greater than 2^9297.
|
||
assert1(e >= 0, "e >= 0")
|
||
assert1(e <= 3528, "e <= 3528")
|
||
return int( ((u32(e)*1217359)>>19) + 1)
|
||
}
|
||
|
||
/*
|
||
|
||
64 bit functions
|
||
|
||
*/
|
||
fn decimal_len_64(u u64) int {
|
||
// http://graphics.stanford.edu/~seander/bithacks.html#IntegerLog10
|
||
log2 := 64 - bits.leading_zeros_64(u) - 1
|
||
t := (log2 + 1) * 1233 >> 12
|
||
return t - bool_to_int(u < powers_of_10[t]) + 1
|
||
}
|
||
|
||
fn shift_right_128(v Uint128, shift int) u64 {
|
||
// The shift value is always modulo 64.
|
||
// In the current implementation of the 64-bit version
|
||
// of Ryu, the shift value is always < 64.
|
||
// (It is in the range [2, 59].)
|
||
// Check this here in case a future change requires larger shift
|
||
// values. In this case this function needs to be adjusted.
|
||
assert1(shift < 64, "shift < 64")
|
||
return (v.hi << u64(64 - shift)) | (v.lo >> u32(shift))
|
||
}
|
||
|
||
fn mul_shift_64(m u64, mul Uint128, shift int) u64 {
|
||
hihi, hilo := bits.mul_64(m, mul.hi)
|
||
lohi, _ := bits.mul_64(m, mul.lo)
|
||
mut sum := Uint128{lo: lohi + hilo,hi: hihi}
|
||
if sum.lo < lohi {
|
||
sum.hi++ // overflow
|
||
}
|
||
return shift_right_128(sum, shift-64)
|
||
}
|
||
|
||
fn pow5_factor_64(v_i u64) u32 {
|
||
mut v := v_i
|
||
for n := u32(0); ; n++ {
|
||
q := v/5
|
||
r := v%5
|
||
if r != 0 {
|
||
return n
|
||
}
|
||
v = q
|
||
}
|
||
return u32(0)
|
||
}
|
||
|
||
fn multiple_of_power_of_five_64(v u64, p u32) bool {
|
||
return pow5_factor_64(v) >= p
|
||
}
|
||
|
||
fn multiple_of_power_of_two_64(v u64, p u32) bool {
|
||
return u32(bits.trailing_zeros_64(v)) >= p
|
||
}
|
||
|
||
/*
|
||
|
||
f64 to string with string format
|
||
|
||
*/
|
||
|
||
// f32_to_str_l return a string with the f32 converted in a string in decimal notation
|
||
pub fn f32_to_str_l(f f64) string {
|
||
return f64_to_str_l(f32(f))
|
||
}
|
||
|
||
// f64_to_str_l return a string with the f64 converted in a string in decimal notation
|
||
pub fn f64_to_str_l(f f64) string {
|
||
s := f64_to_str(f,18)
|
||
|
||
// check for +inf -inf Nan
|
||
if s.len > 2 && (s[0] == `n` || s[1] == `i`) {
|
||
return s
|
||
}
|
||
|
||
m_sgn_flag := false
|
||
mut sgn := 1
|
||
mut b := [26]byte{}
|
||
mut d_pos := 1
|
||
mut i := 0
|
||
mut i1 := 0
|
||
mut exp := 0
|
||
mut exp_sgn := 1
|
||
|
||
// get sign and decimal parts
|
||
for c in s {
|
||
if c == `-` {
|
||
sgn = -1
|
||
i++
|
||
} else if c == `+` {
|
||
sgn = 1
|
||
i++
|
||
}
|
||
else if c >= `0` && c <= `9` {
|
||
b[i1++] = c
|
||
i++
|
||
} else if c == `.` {
|
||
if sgn > 0 {
|
||
d_pos = i
|
||
} else {
|
||
d_pos = i-1
|
||
}
|
||
i++
|
||
} else if c == `e` {
|
||
i++
|
||
break
|
||
} else {
|
||
return "Float conversion error!!"
|
||
}
|
||
}
|
||
b[i1] = 0
|
||
|
||
// get exponent
|
||
if s[i] == `-` {
|
||
exp_sgn = -1
|
||
i++
|
||
} else if s[i] == `+` {
|
||
exp_sgn = 1
|
||
i++
|
||
}
|
||
for c in s[i..] {
|
||
exp = exp * 10 + int(c-`0`)
|
||
}
|
||
|
||
// allocate exp+32 chars for the return string
|
||
mut res := []byte{len: exp+32, init: 0}
|
||
mut r_i := 0 // result string buffer index
|
||
|
||
//println("s:${sgn} b:${b[0]} es:${exp_sgn} exp:${exp}")
|
||
|
||
if sgn == 1 {
|
||
if m_sgn_flag {
|
||
res[r_i++] = `+`
|
||
}
|
||
} else {
|
||
res[r_i++] = `-`
|
||
}
|
||
|
||
i = 0
|
||
if exp_sgn >= 0 {
|
||
for b[i] != 0 {
|
||
res[r_i++] = b[i]
|
||
i++
|
||
if i >= d_pos && exp >= 0 {
|
||
if exp == 0 {
|
||
res[r_i++] = `.`
|
||
}
|
||
exp--
|
||
}
|
||
}
|
||
for exp >= 0 {
|
||
res[r_i++] = `0`
|
||
exp--
|
||
}
|
||
} else {
|
||
mut dot_p := true
|
||
for exp > 0 {
|
||
res[r_i++] = `0`
|
||
exp--
|
||
if dot_p {
|
||
res[r_i++] = `.`
|
||
dot_p = false
|
||
}
|
||
}
|
||
for b[i] != 0 {
|
||
res[r_i++] = b[i]
|
||
i++
|
||
}
|
||
}
|
||
res[r_i] = 0
|
||
return unsafe { tos(res.data,r_i) }
|
||
}
|