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authorIndrajith K L2022-12-03 17:00:20 +0530
committerIndrajith K L2022-12-03 17:00:20 +0530
commitf5c4671bfbad96bf346bd7e9a21fc4317b4959df (patch)
tree2764fc62da58f2ba8da7ed341643fc359873142f /v_windows/v/old/vlib/strconv/f32_str.v
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Adds most of the toolsHEADmaster
Diffstat (limited to 'v_windows/v/old/vlib/strconv/f32_str.v')
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diff --git a/v_windows/v/old/vlib/strconv/f32_str.v b/v_windows/v/old/vlib/strconv/f32_str.v
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+module strconv
+
+/*=============================================================================
+
+f32 to string
+
+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 to string 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
+
+=============================================================================*/
+
+// pow of ten table used by n_digit reduction
+const (
+ ten_pow_table_32 = [
+ u32(1),
+ u32(10),
+ u32(100),
+ u32(1000),
+ u32(10000),
+ u32(100000),
+ u32(1000000),
+ u32(10000000),
+ u32(100000000),
+ u32(1000000000),
+ u32(10000000000),
+ u32(100000000000),
+ ]
+)
+
+//=============================================================================
+// Conversion Functions
+//=============================================================================
+const (
+ mantbits32 = u32(23)
+ expbits32 = u32(8)
+ bias32 = 127 // f32 exponent bias
+ maxexp32 = 255
+)
+
+// max 46 char
+// -3.40282346638528859811704183484516925440e+38
+[direct_array_access]
+pub fn (d Dec32) get_string_32(neg bool, i_n_digit int, i_pad_digit int) string {
+ n_digit := i_n_digit + 1
+ pad_digit := i_pad_digit + 1
+ mut out := d.m
+ // mut out_len := decimal_len_32(out)
+ mut out_len := dec_digits(out)
+ out_len_original := out_len
+
+ mut fw_zeros := 0
+ if pad_digit > out_len {
+ fw_zeros = pad_digit - out_len
+ }
+
+ mut buf := []byte{len: int(out_len + 5 + 1 + 1)} // sign + mant_len + . + e + e_sign + exp_len(2) + \0}
+ mut i := 0
+
+ if neg {
+ if buf.data != 0 {
+ // The buf.data != 0 check here, is needed for clean compilation
+ // with `-cc gcc -cstrict -prod`. Without it, gcc produces:
+ // error: potential null pointer dereference
+ buf[i] = `-`
+ }
+ i++
+ }
+
+ mut disp := 0
+ if out_len <= 1 {
+ disp = 1
+ }
+
+ if n_digit < out_len {
+ // println("orig: ${out_len_original}")
+ out += strconv.ten_pow_table_32[out_len - n_digit - 1] * 5 // round to up
+ out /= strconv.ten_pow_table_32[out_len - n_digit]
+ out_len = n_digit
+ }
+
+ y := i + out_len
+ mut x := 0
+ for x < (out_len - disp - 1) {
+ buf[y - x] = `0` + byte(out % 10)
+ out /= 10
+ i++
+ x++
+ }
+
+ // no decimal digits needed, end here
+ if i_n_digit == 0 {
+ unsafe {
+ buf[i] = 0
+ return tos(&byte(&buf[0]), i)
+ }
+ }
+
+ if out_len >= 1 {
+ buf[y - x] = `.`
+ x++
+ i++
+ }
+
+ if y - x >= 0 {
+ buf[y - x] = `0` + byte(out % 10)
+ i++
+ }
+
+ for fw_zeros > 0 {
+ buf[i] = `0`
+ i++
+ fw_zeros--
+ }
+
+ buf[i] = `e`
+ i++
+
+ mut exp := d.e + out_len_original - 1
+ if exp < 0 {
+ buf[i] = `-`
+ i++
+ exp = -exp
+ } else {
+ buf[i] = `+`
+ i++
+ }
+
+ // Always print two digits to match strconv's formatting.
+ d1 := exp % 10
+ d0 := exp / 10
+ buf[i] = `0` + byte(d0)
+ i++
+ buf[i] = `0` + byte(d1)
+ i++
+ buf[i] = 0
+
+ return unsafe {
+ tos(&byte(&buf[0]), i)
+ }
+}
+
+fn f32_to_decimal_exact_int(i_mant u32, exp u32) (Dec32, bool) {
+ mut d := Dec32{}
+ e := exp - strconv.bias32
+ if e > strconv.mantbits32 {
+ return d, false
+ }
+ shift := strconv.mantbits32 - e
+ mant := i_mant | 0x0080_0000 // implicit 1
+ // mant := i_mant | (1 << mantbits32) // implicit 1
+ d.m = mant >> shift
+ if (d.m << shift) != mant {
+ return d, false
+ }
+ for (d.m % 10) == 0 {
+ d.m /= 10
+ d.e++
+ }
+ return d, true
+}
+
+fn f32_to_decimal(mant u32, exp u32) Dec32 {
+ mut e2 := 0
+ mut m2 := u32(0)
+ if exp == 0 {
+ // We subtract 2 so that the bounds computation has
+ // 2 additional bits.
+ e2 = 1 - strconv.bias32 - int(strconv.mantbits32) - 2
+ m2 = mant
+ } else {
+ e2 = int(exp) - strconv.bias32 - int(strconv.mantbits32) - 2
+ m2 = (u32(1) << strconv.mantbits32) | mant
+ }
+ even := (m2 & 1) == 0
+ accept_bounds := even
+
+ // Step 2: Determine the interval of valid decimal representations.
+ mv := u32(4 * m2)
+ mp := u32(4 * m2 + 2)
+ mm_shift := bool_to_u32(mant != 0 || exp <= 1)
+ mm := u32(4 * m2 - 1 - mm_shift)
+
+ mut vr := u32(0)
+ mut vp := u32(0)
+ mut vm := u32(0)
+ mut e10 := 0
+ mut vm_is_trailing_zeros := false
+ mut vr_is_trailing_zeros := false
+ mut last_removed_digit := byte(0)
+
+ if e2 >= 0 {
+ q := log10_pow2(e2)
+ e10 = int(q)
+ k := pow5_inv_num_bits_32 + pow5_bits(int(q)) - 1
+ i := -e2 + int(q) + k
+
+ vr = mul_pow5_invdiv_pow2(mv, q, i)
+ vp = mul_pow5_invdiv_pow2(mp, q, i)
+ vm = mul_pow5_invdiv_pow2(mm, q, i)
+ if q != 0 && (vp - 1) / 10 <= vm / 10 {
+ // We need to know one removed digit even if we are not
+ // going to loop below. We could use q = X - 1 above,
+ // except that would require 33 bits for the result, and
+ // we've found that 32-bit arithmetic is faster even on
+ // 64-bit machines.
+ l := pow5_inv_num_bits_32 + pow5_bits(int(q - 1)) - 1
+ last_removed_digit = byte(mul_pow5_invdiv_pow2(mv, q - 1, -e2 + int(q - 1) + l) % 10)
+ }
+ if q <= 9 {
+ // The largest power of 5 that fits in 24 bits is 5^10,
+ // but q <= 9 seems to be safe as well. Only one of mp,
+ // mv, and mm can be a multiple of 5, if any.
+ if mv % 5 == 0 {
+ vr_is_trailing_zeros = multiple_of_power_of_five_32(mv, q)
+ } else if accept_bounds {
+ vm_is_trailing_zeros = multiple_of_power_of_five_32(mm, q)
+ } else if multiple_of_power_of_five_32(mp, q) {
+ vp--
+ }
+ }
+ } else {
+ q := log10_pow5(-e2)
+ e10 = int(q) + e2
+ i := -e2 - int(q)
+ k := pow5_bits(i) - pow5_num_bits_32
+ mut j := int(q) - k
+ vr = mul_pow5_div_pow2(mv, u32(i), j)
+ vp = mul_pow5_div_pow2(mp, u32(i), j)
+ vm = mul_pow5_div_pow2(mm, u32(i), j)
+ if q != 0 && ((vp - 1) / 10) <= vm / 10 {
+ j = int(q) - 1 - (pow5_bits(i + 1) - pow5_num_bits_32)
+ last_removed_digit = byte(mul_pow5_div_pow2(mv, u32(i + 1), j) % 10)
+ }
+ if q <= 1 {
+ // {vr,vp,vm} is trailing zeros if {mv,mp,mm} has at
+ // least q trailing 0 bits. mv = 4 * m2, so it always
+ // has at least two trailing 0 bits.
+ vr_is_trailing_zeros = true
+ if accept_bounds {
+ // mm = mv - 1 - mm_shift, so it has 1 trailing 0 bit
+ // if mm_shift == 1.
+ vm_is_trailing_zeros = mm_shift == 1
+ } else {
+ // mp = mv + 2, so it always has at least one
+ // trailing 0 bit.
+ vp--
+ }
+ } else if q < 31 {
+ vr_is_trailing_zeros = multiple_of_power_of_two_32(mv, q - 1)
+ }
+ }
+
+ // Step 4: Find the shortest decimal representation
+ // in the interval of valid representations.
+ mut removed := 0
+ mut out := u32(0)
+ if vm_is_trailing_zeros || vr_is_trailing_zeros {
+ // General case, which happens rarely (~4.0%).
+ for vp / 10 > vm / 10 {
+ vm_is_trailing_zeros = vm_is_trailing_zeros && (vm % 10) == 0
+ vr_is_trailing_zeros = vr_is_trailing_zeros && (last_removed_digit == 0)
+ last_removed_digit = byte(vr % 10)
+ vr /= 10
+ vp /= 10
+ vm /= 10
+ removed++
+ }
+ if vm_is_trailing_zeros {
+ for vm % 10 == 0 {
+ vr_is_trailing_zeros = vr_is_trailing_zeros && (last_removed_digit == 0)
+ last_removed_digit = byte(vr % 10)
+ vr /= 10
+ vp /= 10
+ vm /= 10
+ removed++
+ }
+ }
+ if vr_is_trailing_zeros && (last_removed_digit == 5) && (vr % 2) == 0 {
+ // Round even if the exact number is .....50..0.
+ last_removed_digit = 4
+ }
+ out = vr
+ // We need to take vr + 1 if vr is outside bounds
+ // or we need to round up.
+ if (vr == vm && (!accept_bounds || !vm_is_trailing_zeros)) || last_removed_digit >= 5 {
+ out++
+ }
+ } else {
+ // Specialized for the common case (~96.0%). Percentages below
+ // are relative to this. Loop iterations below (approximately):
+ // 0: 13.6%, 1: 70.7%, 2: 14.1%, 3: 1.39%, 4: 0.14%, 5+: 0.01%
+ for vp / 10 > vm / 10 {
+ last_removed_digit = byte(vr % 10)
+ vr /= 10
+ vp /= 10
+ vm /= 10
+ removed++
+ }
+ // We need to take vr + 1 if vr is outside bounds
+ // or we need to round up.
+ out = vr + bool_to_u32(vr == vm || last_removed_digit >= 5)
+ }
+
+ return Dec32{
+ m: out
+ e: e10 + removed
+ }
+}
+
+//=============================================================================
+// String Functions
+//=============================================================================
+
+// f32_to_str return a string in scientific notation with max n_digit after the dot
+pub fn f32_to_str(f f32, n_digit int) string {
+ mut u1 := Uf32{}
+ u1.f = f
+ u := unsafe { u1.u }
+
+ neg := (u >> (strconv.mantbits32 + strconv.expbits32)) != 0
+ mant := u & ((u32(1) << strconv.mantbits32) - u32(1))
+ exp := (u >> strconv.mantbits32) & ((u32(1) << strconv.expbits32) - u32(1))
+
+ // println("${neg} ${mant} e ${exp-bias32}")
+
+ // Exit early for easy cases.
+ if (exp == strconv.maxexp32) || (exp == 0 && mant == 0) {
+ return get_string_special(neg, exp == 0, mant == 0)
+ }
+
+ mut d, ok := f32_to_decimal_exact_int(mant, exp)
+ if !ok {
+ // println("with exp form")
+ d = f32_to_decimal(mant, exp)
+ }
+
+ // println("${d.m} ${d.e}")
+ return d.get_string_32(neg, n_digit, 0)
+}
+
+// f32_to_str return a string in scientific notation with max n_digit after the dot
+pub fn f32_to_str_pad(f f32, n_digit int) string {
+ mut u1 := Uf32{}
+ u1.f = f
+ u := unsafe { u1.u }
+
+ neg := (u >> (strconv.mantbits32 + strconv.expbits32)) != 0
+ mant := u & ((u32(1) << strconv.mantbits32) - u32(1))
+ exp := (u >> strconv.mantbits32) & ((u32(1) << strconv.expbits32) - u32(1))
+
+ // println("${neg} ${mant} e ${exp-bias32}")
+
+ // Exit early for easy cases.
+ if (exp == strconv.maxexp32) || (exp == 0 && mant == 0) {
+ return get_string_special(neg, exp == 0, mant == 0)
+ }
+
+ mut d, ok := f32_to_decimal_exact_int(mant, exp)
+ if !ok {
+ // println("with exp form")
+ d = f32_to_decimal(mant, exp)
+ }
+
+ // println("${d.m} ${d.e}")
+ return d.get_string_32(neg, n_digit, n_digit)
+}