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#
#
# 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
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