ref: e44ea2b103b1d7964a4ad345e7ce6bd24615ebf0
dir: /sys/man/2/encode/
.TH ENCODE 2 .SH NAME dec64, enc64, dec32, enc32, dec16, enc16, \ dec64x, enc64x, dec32x, enc32x, \ dec64chr, enc64chr, dec32chr, enc32chr, dec16chr, enc16chr, \ encodefmt \- encoding byte arrays as strings .SH SYNOPSIS .B #include <u.h> .br .B #include <libc.h> .PP .B int dec64(uchar *out, int lim, char *in, int n) .PP .B int dec64x(uchar *out, int lim, char *in, int n, int (*map)(int)) .PP .B int enc64(char *out, int lim, uchar *in, int n) .PP .B int enc64x(char *out, int lim, uchar *in, int n, int (*map)(int)) .PP .B int dec32(uchar *out, int lim, char *in, int n) .PP .B int dec32x(uchar *out, int lim, char *in, int n, int (*map)(int)) .PP .B int enc32(char *out, int lim, uchar *in, int n) .PP .B int enc32x(char *out, int lim, uchar *in, int n, int (*map)(int)) .PP .B int dec16(uchar *out, int lim, char *in, int n) .PP .B int enc16(char *out, int lim, uchar *in, int n) .PP .B int dec64chr(int c) .PP .B int enc64chr(int o) .PP .B int dec32chr(int c) .PP .B int enc32chr(int o) .PP .B int dec16chr(int c) .PP .B int enc16chr(int o) .PP .B int encodefmt(Fmt*) .SH DESCRIPTION The functions described here handle encoding and decoding of bytes to printable ASCII strings as specified by RFC4648. .PP .IR Enc16 , .I enc32 and .I enc64 create null terminated strings. They return the size of the encoded string (without the null) or -1 if the encoding fails. The encoding fails if .IR lim , the length of the output buffer (including null), is too small. .PP .IR Dec16 , .I dec32 and .I dec64 return the number of bytes decoded or -1 if the decoding fails. The decoding fails if the output buffer is not large enough or, for base 32, if the input buffer length is not a multiple of 8. .PP .IR Dec16chr , .I dec32chr and .I dec64chr return the value for a symbol of the alphabet or -1 when the symbol is not in the alphabet. .PP .IR Enc16chr , .I enc32chr and .I enc64chr encode a symbol of the alphabet given a value. if the value is out of range then zero is returned. .PP The .I enc64x and .I enc32x variants are identical to the above, except that they take a function mapping from an arbitrary index in the alphabet to the encoded character. For example, in the following 32-character alphabet, .EX .I ABCDEFGHIJKLMNOPQRSTUVWXYZ234567 .EE the chr function would map the value .I 3 to the character .IR D . The .I dec64x and .I dec32x variants are similar to the above, however the function passed maps from a character within the alphabet to the index within the alphabet. .PP .I Encodefmt can be used with .IR fmtinstall (2) and .IR print (2) to print encoded representations of byte arrays. The verbs are .TP .B H base 16 (i.e. hexadecimal). The default encoding is in upper case. The .B l flag forces lower case. .TP .B < base 32. The default is upper case, same as .BR H . .TP .B [ base 64 (same as MIME) .PD .PP The length of the array is specified as .IR f2 . For example, to display a 15 byte array as hex: .EX char x[15]; fmtinstall('H', encodefmt); print("%.*H\\n", sizeof x, x); .EE .SH SOURCE .B /sys/src/libc/port/u16.c .br .B /sys/src/libc/port/u32.c .br .B /sys/src/libc/port/u64.c .br .B /sys/src/libc/port/encodefmt.c .SH HISTORY In Jan 2018, base 32 encoding was changed from non-standard to standard RFC4648 alphabet. .TP old: .B "23456789abcdefghijkmnpqrstuvwxyz" .TP new: .B "ABCDEFGHIJKLMNOPQRSTUVWXYZ234567"