commit d6116f15c38be34e8d5bba4d5d183f78313b5e9a
Author: styan <styan@tilde.black>
Date:   Wed Jun 10 08:16:08 2020 +0000

    Initial commit

diff --git a/Makefile b/Makefile
new file mode 100644
index 0000000..31e8583
--- /dev/null
+++ b/Makefile
@@ -0,0 +1,45 @@
+.POSIX:
+default:
+all:
+install:\
+	install-baseenc\
+	install-basedec\
+	install-gmi2html\
+	install-tac
+install-baseenc:
+	install -m755 baseenc.sh\
+	    "$$BASEDIR$${PREFIX-/usr/local}/bin/base64enc"
+	ln -f -- "$$BASEDIR$${PREFIX-/usr/local}/bin/base64enc"\
+	    "$$BASEDIR$${PREFIX-/usr/local}/bin/base32enc"
+	ln -f -- "$$BASEDIR$${PREFIX-/usr/local}/bin/base64enc"\
+	    "$$BASEDIR$${PREFIX-/usr/local}/bin/base16enc"
+install-basedec:
+	install -m755 basedec.sh\
+	    "$$BASEDIR$${PREFIX-/usr/local}/bin/base64dec"
+	ln -f -- "$$BASEDIR$${PREFIX-/usr/local}/bin/base64dec"\
+	    "$$BASEDIR$${PREFIX-/usr/local}/bin/base32dec"
+	ln -f -- "$$BASEDIR$${PREFIX-/usr/local}/bin/base64dec"\
+	    "$$BASEDIR$${PREFIX-/usr/local}/bin/base16dec"
+install-gmi2html:
+	install -m755 gmi2html.sh\
+	    "$$BASEDIR$${PREFIX-/usr/local}/bin/gmi2html"
+install-tac:
+	install -m755 tac.sh "$$BASEDIR$${PREFIX-/usr/local}/bin/tac"
+linstall:\
+	linstall-baseenc\
+	linstall-basedec\
+	linstall-gmi2html\
+	linstall-tac
+linstall-baseenc:
+	install -m755 baseenc.sh "$$HOME/bin/base64enc"
+	ln -f -- "$$HOME/bin/base64enc" "$$HOME/bin/base32enc"
+	ln -f -- "$$HOME/bin/base64enc" "$$HOME/bin/base16enc"
+linstall-basedec:
+	install -m755 basedec.sh "$$HOME/bin/base64dec"
+	ln -f -- "$$HOME/bin/base64dec" "$$HOME/bin/base32dec"
+	ln -f -- "$$HOME/bin/base64dec" "$$HOME/bin/base16dec"
+linstall-gmi2html:
+	install -m755 gmi2html.sh "$$HOME/bin/gmi2html"
+linstall-tac:
+	install -m755 tac.sh "$$HOME/bin/tac"
+clean:
diff --git a/basedec.sh b/basedec.sh
new file mode 100644
index 0000000..79ce856
--- /dev/null
+++ b/basedec.sh
@@ -0,0 +1,86 @@
+#!/bin/sh
+usage() {
+	printf 'usage: %s [-t type] [file ...]\n' "${0##*/}" >&2
+	exit 64
+}
+case "$(printf %s "${0##*/}" | tr A-Z a-z)" in
+	*16*)	type=16;;
+	*32hex*|*32x*)
+		type=32x;;
+	*32*)	type=32;;
+	*64s*)	type=64s;;
+	*64*)	type=64;;
+	*)	type=64;;
+esac
+b16=0123456789ABCDEF
+b32=ABCDEFGHIJKLMNOPQRSTUVWXYZ234567
+b32hex=0123456789ABCDEFGHIJKLMNOPQRSTUV
+b64=ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/
+b64safe=ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789-_
+while getopts t: opt; do
+	case "$opt" in
+	t)	case "$(printf %s "$OPTARG" | tr A-Z a-z)" in
+		16)	type=16;;
+		32)	type=32;;
+		32x)	type=32x;;
+		64)	type=64;;
+		64s|64safe)
+			type=64s;;
+		*)	usage;;
+		esac
+		;;
+	*)	usage;;
+	esac
+done
+shift $((OPTIND - 1))
+case "$type" in
+16)	alphabet="$b16"
+	insensitive=1
+	bits=4;;
+32)	alphabet="$b32"
+	insensitive=1
+	bits=5;;
+32x)	alphabet="$b32hex"
+	insensitive=1
+	bits=5;;
+64)	alphabet="$b64"
+	insensitive=0
+	bits=6;;
+64s)	alphabet="$b64safe"
+	insensitive=0
+	bits=6;;
+*)	usage;; # Unreachable
+esac
+cat -- "$@" | awk -vbits="$bits" -valphabet="$alphabet" \
+    -vinsensitive="$insensitive" '
+	function leftshift(a, b) {
+		return a * 2 ** b
+	}
+	function rightshift(a, b) {
+		return int(a / 2 ** b)
+	}
+	function mask(a, b) {
+		return a > 0 ? a % leftshift(1, b) : a
+	}
+	BEGIN {
+		FS=""
+		split(alphabet, al, "")
+		for (n in al)
+			a[al[n]] = n - 1
+		if (insensitive)
+			for (c in a)
+				a[tolower(c)] = a[c]
+	} {
+		for (i = 1; i <= NF; i++) {
+			if ($i in a) {
+				t = leftshift(t, bits) + a[$i]
+				b += bits
+				while (b >= 8) {
+					b -= 8 
+					printf "%c", rightshift(t, b)
+					t = mask(t, b)
+					count++
+				}
+			}
+		}
+	}'
diff --git a/baseenc.sh b/baseenc.sh
new file mode 100644
index 0000000..909c21c
--- /dev/null
+++ b/baseenc.sh
@@ -0,0 +1,112 @@
+#!/bin/sh
+usage() {
+	printf 'usage: %s [-np] [-a alphabet] [-t type] [file ...]\n' \
+	    "${0##*/}" >&2
+	exit 64
+}
+case "$(printf %s "${0##*/}" | tr A-Z a-z)" in
+	*16l*|*hexl*)
+		type=16l;;
+	*16*)	type=16u;;
+	*32hexl*|*32x*l)
+		type=32x;;
+	*32hex*|*32x*)
+		type=32X;;
+	*32l*)	type=32l;;
+	*32*)	type=32u;;
+	*64s*)	type=64s;;
+	*)	type=64;;
+esac
+b16upper=0123456789ABCDEF
+b16lower=0123456789abcdef
+b32upper=ABCDEFGHIJKLMNOPQRSTUVWXYZ234567
+b32lower=abcdefghijklmnopqrstuvwxyz234567
+b32hexupper=0123456789ABCDEFGHIJKLMNOPQRSTUV
+b32hexlower=0123456789abcdefghijklmnopqrstuv
+b64=ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/
+b64safe=ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789-_
+alphabet=
+pad=1
+nl=1
+while getopts a:npt: opt; do
+	case "$opt" in
+	a)	alphabet="$OPTARG";;
+	n)	nl=0;;
+	p)	pad=0;;
+	t)	case "$(printf %s "$OPTARG" | tr A-WYZ a-wyz)" in
+		16|16u|16upper)
+			type=16u;;
+		16l|16lower)
+			type=16l;;
+		32|32u|32upper)
+			type=32u;;
+		32l|32lower)
+			type=32l;;
+		32X)	type=32X;;
+		32x)	type=32x;;
+		64)	type=64;;
+		64s|64safe)
+			type=64s;;
+		*)	usage;;
+		esac
+		;;
+	*)	usage;;
+	esac
+done
+shift $((OPTIND - 1))
+case "$type" in
+16u)	alphabet="${alphabet:-$b16upper}"
+	bits=4;;
+16l)	alphabet="${alphabet:-$b16lower}"
+	bits=4;;
+32u)	alphabet="${alphabet:-$b32upper}"
+	bits=5;;
+32l)	alphabet="${alphabet:-$b32lower}"
+	bits=5;;
+32X)	alphabet="${alphabet:-$b32hexupper}"
+	bits=5;;
+32x)	alphabet="${alphabet:-$b32hexlower}"
+	bits=5;;
+64)	alphabet="${alphabet:-$b64}"
+	bits=6;;
+64s)	alphabet="${alphabet:-$b64safe}"
+	bits=6;;
+*)	usage;; # Unreachable
+esac
+od -An -tu1 -v -- "$@" | sed 's/^  *//' | tr -s ' ' '\n' |
+    sed 's/^00*//' | awk -vbits="$bits" -valphabet="$alphabet" \
+    -vnl="$nl" -vpad="$pad" '
+	function leftshift(a, b) {
+		return a * 2 ** b
+	}
+	function rightshift(a, b) {
+		return int(a / 2 ** b)
+	}
+	function mask(a, b) {
+		return a > 0 ? a % leftshift(1, b) : a
+	}
+	BEGIN {
+		split(alphabet, a, "")
+	} {
+		t = leftshift(t, 8) + $0
+		b += 8
+		while (b >= bits) {
+			b -= bits
+			printf "%s", a[rightshift(t, b) + 1]
+			t = mask(t, b)
+			count++
+		}
+	} END {
+		if (b > 0) {
+			printf "%s", a[leftshift(t, bits - b) + 1]
+			count++
+		}
+		if (pad && bits == 5)
+			for (count += 0; count % 8 != 0; count++)
+				printf "="
+		if (pad && bits == 6)
+			for (count += 0; count % 4 != 0; count++)
+				printf "="
+		if (nl)
+			print ""
+	}'
diff --git a/gmi2html.sh b/gmi2html.sh
new file mode 100644
index 0000000..f8b8598
--- /dev/null
+++ b/gmi2html.sh
@@ -0,0 +1,91 @@
+#!/bin/sh
+usage() {
+	echo >&2 \
+	'usage: gmi2html [-h header] [-p prefix] [-s suffix] [file ...]'
+	exit 64
+}
+gmi2html() {
+	if [ "$prefix" ]; then
+		printf '%s\n' "$prefix"
+	fi
+	awk '
+	function hescape(s) {
+		gsub(/&/, "&amp;", s)
+		gsub(/</, "&lt;", s)
+		gsub(/>/, "&gt;", s)
+		gsub(/"/, "&quot;", s)
+		return s
+	}
+	/^```/ {
+		sub(/^```/, "")
+		pre = !pre
+		if (pre)
+			print "\t<pre alt=\"" hescape($0) "\">"
+		else
+			print "\t</pre>"
+	} !pre && /^=>/ {
+		u = $2
+		$1 = ""
+		$2 = ""
+		sub(/^[[:space:]]+/, "")
+		if ($0 !~ /./)
+			$0 = u
+		print "\t<a href=\"" hescape(u) "\">" hescape($0) "</a>"
+		next
+	} !pre && /^###/ {
+		sub(/^###[[:space:]]*/, "")
+		id = tolower($0)
+		gsub(/[^[:alnum:]]+/, "-", id)
+		print "\t<h1 id=\"" hescape(id) "\">" \
+		    hescape($0) "</h1>"
+		next
+	} !pre && /^##/ {
+		sub(/^##[[:space:]]*/, "")
+		id = tolower($0)
+		gsub(/[^[:alnum:]]+/, "-", id)
+		print "\t<h2 id=\"" hescape(id) "\">" \
+		    hescape($0) "</h2>"
+		next
+	} !pre && /^#/ {
+		sub(/^#[[:space:]]*/, "")
+		id = tolower($0)
+		gsub(/[^[:alnum:]]+/, "-", id)
+		print "\t<h3 id=\"" hescape(id) "\">" \
+		    hescape($0) "</h3>"
+		next
+	} !pre && /^[[:space:]]*$/ {
+		print "\t<br/>"
+		next
+	} {
+		print hescape($0)
+	}
+	END {
+		if (pre)
+			print "\t</pre>"
+	}'
+	if [ "$suffix" ]; then
+		printf '%s\n' "$suffix"
+	fi
+}
+header='<!doctype html>'
+prefix='<html><head></head><body><article><p>'
+suffix='</p></article></body></html>'
+while getopts h:p:s: opt; do
+	case "$opt" in
+	h)	header="$OPTARG";;
+	p)	prefix="$OPTARG";;
+	s)	suffix="$OPTARG";;
+	*)	usage;;
+	esac
+done
+shift $((OPTIND - 1))
+if [ "$header" ]; then
+	printf '%s\n' "$header"
+fi
+if [ "$#" -eq 0 ]; then
+	gmi2html
+	exit
+fi
+for f in "$@"; do
+	gmi2html < "$f"
+done
diff --git a/tac.sh b/tac.sh
new file mode 100644
index 0000000..913ae4f
--- /dev/null
+++ b/tac.sh
@@ -0,0 +1,26 @@
+#!/bin/sh
+usage() {
+	echo 'usage: tac [-b] [-s separator] [file ...]' >&2
+	exit 64
+}
+bflag=
+rs='\n'
+while getopts bs: opt; do
+	case "$opt" in
+	b)	bflag=1;;
+	s)	rs="$OPTARG";;
+	*)	usage;;
+	esac
+done
+shift $((OPTIND - 1))
+rs="$(printf %s "$rs" | sed 's/[][)(}{.+?*^$]/\\&/g')"
+awk -vRS="$rs" -vORS="$rs" -vb="$bflag" '{
+	a[NR] = $0
+} END {
+	if (b)
+		for (i = NR; i > 0; i--)
+			printf "%s%s", ORS, a[i]
+	else
+		for (i = NR; i > 0; i--)
+			printf "%s%s", a[i], ORS
+}' "$@"