diff options
Diffstat (limited to 'lib/pure/base64.nim')
| -rw-r--r-- | lib/pure/base64.nim | 242 |
1 files changed, 126 insertions, 116 deletions
diff --git a/lib/pure/base64.nim b/lib/pure/base64.nim index 685313551..4e59a6ca6 100644 --- a/lib/pure/base64.nim +++ b/lib/pure/base64.nim @@ -1,117 +1,127 @@ -# -# -# Nimrod's Runtime Library -# (c) Copyright 2010 Andreas Rumpf -# -# See the file "copying.txt", included in this -# distribution, for details about the copyright. -# - -## This module implements a base64 encoder and decoder. - -const - cb64 = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/" - -proc encode*(s: string, lineLen = 75, newLine="\13\10"): string = - ## encodes `s` into base64 representation. After `lineLen` characters, a - ## `newline` is added. - var total = ((len(s) + 2) div 3) * 4 - var numLines = (total + lineLen - 1) div lineLen +# +# +# Nimrod's Runtime Library +# (c) Copyright 2010 Andreas Rumpf +# +# See the file "copying.txt", included in this +# distribution, for details about the copyright. +# + +## This module implements a base64 encoder and decoder. + +const + cb64 = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/" + +template encodeInternal(s: expr, lineLen: int, newLine: string): stmt {.immediate.} = + ## encodes `s` into base64 representation. After `lineLen` characters, a + ## `newline` is added. + var total = ((len(s) + 2) div 3) * 4 + var numLines = (total + lineLen - 1) div lineLen if numLines > 0: inc(total, (numLines-1) * newLine.len) - - result = newString(total) - var i = 0 - var r = 0 - var currLine = 0 - while i < s.len - 2: - var a = ord(s[i]) - var b = ord(s[i+1]) - var c = ord(s[i+2]) - result[r] = cb64[a shr 2] - result[r+1] = cb64[((a and 3) shl 4) or ((b and 0xF0) shr 4)] - result[r+2] = cb64[((b and 0x0F) shl 2) or ((c and 0xC0) shr 6)] - result[r+3] = cb64[c and 0x3F] - inc(r, 4) - inc(i, 3) - inc(currLine, 4) - if currLine >= lineLen and i != s.len-2: - for x in items(newLine): - result[r] = x - inc(r) - currLine = 0 - - if i < s.len-1: - var a = ord(s[i]) - var b = ord(s[i+1]) - result[r] = cb64[a shr 2] - result[r+1] = cb64[((a and 3) shl 4) or ((b and 0xF0) shr 4)] - result[r+2] = cb64[((b and 0x0F) shl 2)] - result[r+3] = '=' - if r+4 != result.len: - setLen(result, r+4) - elif i < s.len: - var a = ord(s[i]) - result[r] = cb64[a shr 2] - result[r+1] = cb64[(a and 3) shl 4] - result[r+2] = '=' - result[r+3] = '=' - if r+4 != result.len: - setLen(result, r+4) - else: - assert(r == result.len) - -proc decodeByte(b: char): int {.inline.} = - case b - of '+': result = ord('>') - of '0'..'9': result = ord(b) + 4 - of 'A'..'Z': result = ord(b) - ord('A') - of 'a'..'z': result = ord(b) - 71 - else: result = 63 - -proc decode*(s: string): string = - ## decodes a string in base64 representation back into its original form. - ## Whitespace is skipped. - const Whitespace = {' ', '\t', '\v', '\r', '\l', '\f'} - var total = ((len(s) + 3) div 4) * 3 - # total is an upper bound, as we will skip arbitrary whitespace: - result = newString(total) - - var i = 0 - var r = 0 - while true: - while s[i] in Whitespace: inc(i) - if i < s.len-3: - var a = s[i].decodeByte - var b = s[i+1].decodeByte - var c = s[i+2].decodeByte - var d = s[i+3].decodeByte - - result[r] = chr((a shl 2) and 0xff or ((b shr 4) and 0x03)) - result[r+1] = chr((b shl 4) and 0xff or ((c shr 2) and 0x0F)) - result[r+2] = chr((c shl 6) and 0xff or (d and 0x3F)) - inc(r, 3) - inc(i, 4) - else: break - assert i == s.len - # adjust the length: - if i > 0 and s[i-1] == '=': - dec(r) - if i > 1 and s[i-2] == '=': dec(r) - setLen(result, r) - -when isMainModule: - assert encode("leasure.") == "bGVhc3VyZS4=" - assert encode("easure.") == "ZWFzdXJlLg==" - assert encode("asure.") == "YXN1cmUu" - assert encode("sure.") == "c3VyZS4=" - - const longText = """Man is distinguished, not only by his reason, but by this - singular passion from other animals, which is a lust of the mind, - that by a perseverance of delight in the continued and indefatigable - generation of knowledge, exceeds the short vehemence of any carnal - pleasure.""" - const tests = ["", "abc", "xyz", "man", "leasure.", "sure.", "easure.", - "asure.", longText] - for t in items(tests): - assert decode(encode(t)) == t - + + result = newString(total) + var i = 0 + var r = 0 + var currLine = 0 + while i < s.len - 2: + var a = ord(s[i]) + var b = ord(s[i+1]) + var c = ord(s[i+2]) + result[r] = cb64[a shr 2] + result[r+1] = cb64[((a and 3) shl 4) or ((b and 0xF0) shr 4)] + result[r+2] = cb64[((b and 0x0F) shl 2) or ((c and 0xC0) shr 6)] + result[r+3] = cb64[c and 0x3F] + inc(r, 4) + inc(i, 3) + inc(currLine, 4) + if currLine >= lineLen and i != s.len-2: + for x in items(newLine): + result[r] = x + inc(r) + currLine = 0 + + if i < s.len-1: + var a = ord(s[i]) + var b = ord(s[i+1]) + result[r] = cb64[a shr 2] + result[r+1] = cb64[((a and 3) shl 4) or ((b and 0xF0) shr 4)] + result[r+2] = cb64[((b and 0x0F) shl 2)] + result[r+3] = '=' + if r+4 != result.len: + setLen(result, r+4) + elif i < s.len: + var a = ord(s[i]) + result[r] = cb64[a shr 2] + result[r+1] = cb64[(a and 3) shl 4] + result[r+2] = '=' + result[r+3] = '=' + if r+4 != result.len: + setLen(result, r+4) + else: + assert(r == result.len) + +proc encode*[T:TInteger|char](s: openarray[T], lineLen = 75, newLine="\13\10"): string = + ## encodes `s` into base64 representation. After `lineLen` characters, a + ## `newline` is added. + encodeInternal(s, lineLen, newLine) + +proc encode*(s: string, lineLen = 75, newLine="\13\10"): string = + ## encodes `s` into base64 representation. After `lineLen` characters, a + ## `newline` is added. + encodeInternal(s, lineLen, newLine) + +proc decodeByte(b: char): int {.inline.} = + case b + of '+': result = ord('>') + of '0'..'9': result = ord(b) + 4 + of 'A'..'Z': result = ord(b) - ord('A') + of 'a'..'z': result = ord(b) - 71 + else: result = 63 + +proc decode*(s: string): string = + ## decodes a string in base64 representation back into its original form. + ## Whitespace is skipped. + const Whitespace = {' ', '\t', '\v', '\r', '\l', '\f'} + var total = ((len(s) + 3) div 4) * 3 + # total is an upper bound, as we will skip arbitrary whitespace: + result = newString(total) + + var i = 0 + var r = 0 + while true: + while s[i] in Whitespace: inc(i) + if i < s.len-3: + var a = s[i].decodeByte + var b = s[i+1].decodeByte + var c = s[i+2].decodeByte + var d = s[i+3].decodeByte + + result[r] = chr((a shl 2) and 0xff or ((b shr 4) and 0x03)) + result[r+1] = chr((b shl 4) and 0xff or ((c shr 2) and 0x0F)) + result[r+2] = chr((c shl 6) and 0xff or (d and 0x3F)) + inc(r, 3) + inc(i, 4) + else: break + assert i == s.len + # adjust the length: + if i > 0 and s[i-1] == '=': + dec(r) + if i > 1 and s[i-2] == '=': dec(r) + setLen(result, r) + +when isMainModule: + assert encode("leasure.") == "bGVhc3VyZS4=" + assert encode("easure.") == "ZWFzdXJlLg==" + assert encode("asure.") == "YXN1cmUu" + assert encode("sure.") == "c3VyZS4=" + + const longText = """Man is distinguished, not only by his reason, but by this + singular passion from other animals, which is a lust of the mind, + that by a perseverance of delight in the continued and indefatigable + generation of knowledge, exceeds the short vehemence of any carnal + pleasure.""" + const tests = ["", "abc", "xyz", "man", "leasure.", "sure.", "easure.", + "asure.", longText] + for t in items(tests): + assert decode(encode(t)) == t + |