From: Lady <redacted>
Date: Sat, 3 Feb 2024 23:25:56 +0000 (-0500)
Subject: Just manually parse hexadecimal in Awk
X-Git-Tag: 0.5.2
X-Git-Url: https://git.ladys.computer/Shushe/commitdiff_plain/1b5b8657a480df45761bb47b2a6e8336d6504c9b?hp=eb3b42b3ee2ac34f01624d360b2ae3195151cfd4

Just manually parse hexadecimal in Awk

The biggest performance bottleneck in this code was the fact that, for
compatibility reasons, Awk was piping hexadecimal numbers to the shell
in order to parse them. (Macintosh Awk can parse hexadecimal numbers in
`printf`, but G·N·U Awk cannot.)

Because the hexadecimal number is known to be two digits, it’s easy to
just parse it in Awk directly, avoiding the shell pipe and considerably
speeding up the program.
---

diff --git a/GNUmakefile b/GNUmakefile
index d0989c1..8306fc1 100644
--- a/GNUmakefile
+++ b/GNUmakefile
@@ -216,7 +216,7 @@ override silent := $(if $(VERBOSE),,@)
 override sedesc = $(subst /,[/],$(subst $$,\$$,$(subst *,\*,$(subst .,\.,$(subst [,\[,$(subst ^,\^,$(subst \,\\,$1)))))))
 
 # The command to use for percent‐decoding.
-override perdeccmd := $(SED) 's/|/%7C/g;s/[\]/%5C/g;s/%[0-9A-Fa-f]\{2\}/|&|/g' | $(TR) '|' '\n' | $(SED) '/^%[0-9A-Fa-f]\{2\}$$/!s/%/|%25|/' | $(TR) '|' '\n' | $(AWK) '$$0!~/%/{printf "%s",$$0}/%/{sub("%","0x");cmd="$(XARGS) $(PRINTF) \"%04o\"";printf "%s","\\";printf "%s",$$0|cmd;close(cmd)}' | $(XARGS) -0 $(PRINTF) '%b'
+override perdeccmd := $(SED) 's/|/%7C/g;s/[\]/%5C/g;s/%[0-9A-Fa-f]\{2\}/|&|/g' | $(TR) '|' '\n' | $(SED) '/^%[0-9A-Fa-f]\{2\}$$/!s/%/|%25|/' | $(TR) '|' '\n' | $(AWK) '$$0!~/%/{printf "%s",$$0}/%/{d="0123456789ABCDEF";v=substr(toupper($$0),2,2);printf "\\%04o",(index(d,substr(v,1,1))-1)*16+index(d,substr(v,2,1))-1}' | $(XARGS) -0 $(PRINTF) '%b'
 
 # (callable) Percent‐decode the given strings.
 #