mirror of
https://github.com/nim-lang/Nim.git
synced 2025-12-28 17:04:41 +00:00
60 lines
1.8 KiB
Nim
60 lines
1.8 KiB
Nim
#
|
|
#
|
|
# Nim's Runtime Library
|
|
# (c) Copyright 2019 Nim contributors
|
|
#
|
|
# See the file "copying.txt", included in this
|
|
# distribution, for details about the copyright.
|
|
#
|
|
|
|
proc c_sprintf(buf, frmt: cstring): cint {.header: "<stdio.h>",
|
|
importc: "sprintf", varargs, noSideEffect.}
|
|
|
|
proc writeToBuffer(buf: var array[65, char]; value: cstring) =
|
|
var i = 0
|
|
while value[i] != '\0':
|
|
buf[i] = value[i]
|
|
inc i
|
|
|
|
proc writeFloatToBuffer*(buf: var array[65, char]; value: BiggestFloat): int =
|
|
## This is the implementation to format floats in the Nim
|
|
## programming language. The specific format for floating point
|
|
## numbers is not specified in the Nim programming language and
|
|
## might change slightly in the future, but at least wherever you
|
|
## format a float, it should be consistent.
|
|
##
|
|
## returns the amount of bytes written to `buf` not counting the
|
|
## terminating '\0' character.
|
|
##
|
|
## * `buf` - A buffer to write into. The buffer does not need to be
|
|
## initialized and it will be overridden.
|
|
##
|
|
var n: int = c_sprintf(addr buf, "%.16g", value)
|
|
var hasDot = false
|
|
for i in 0..n-1:
|
|
if buf[i] == ',':
|
|
buf[i] = '.'
|
|
hasDot = true
|
|
elif buf[i] in {'a'..'z', 'A'..'Z', '.'}:
|
|
hasDot = true
|
|
if not hasDot:
|
|
buf[n] = '.'
|
|
buf[n+1] = '0'
|
|
buf[n+2] = '\0'
|
|
result = n + 2
|
|
else:
|
|
result = n
|
|
# On Windows nice numbers like '1.#INF', '-1.#INF' or '1.#NAN' or 'nan(ind)'
|
|
# of '-1.#IND' are produced.
|
|
# We want to get rid of these here:
|
|
if buf[n-1] in {'n', 'N', 'D', 'd', ')'}:
|
|
writeToBuffer(buf, "nan")
|
|
result = 3
|
|
elif buf[n-1] == 'F':
|
|
if buf[0] == '-':
|
|
writeToBuffer(buf, "-inf")
|
|
result = 4
|
|
else:
|
|
writeToBuffer(buf, "inf")
|
|
result = 3
|