commit f0814f307bb304b10bf2a3603952fbf4d70b00b3
from: Sven M. Hallberg <pesco@khjk.org>
date: Wed Nov 22 23:46:54 2023 UTC

stick to rand for portable

This backs out commit 40c37b5c (use arc4random) except for the header
include.

Crappy old rand(3) is fine for this program. It's just bad form on
OpenBSD and its linker spews an annoying warning about it.

FWIW, Linux finally got arc4random(3) with glibc >= 2.36 (2022) so it
could actually be considered fairly portable now. However, for the time
being, I'd like to still support older systems. NB, the closest "native"
alternative, getentropy(3), appears in glibc >= 2.25 (2017), so even it is
not exactly ancient, yet. Thus, instead of mucking around with wrappers,
feature flags and conditional compilation, rand() is still it for portable.

commit - aba7856aa944db993d533420fa5861adfb294a7f
commit + f0814f307bb304b10bf2a3603952fbf4d70b00b3
blob - 38193f39f73b7e650f94ae57f386b88611662c35
blob + 13f06ec0f1629226d9b385f8f22f39fb4faf1390
--- teach.c
+++ teach.c
@@ -327,6 +327,7 @@ teach(void)
 	mistake = initmis;
 	avgtime = initrsp;
 	vartime = initvar;
+	srand(time(NULL));
 
 	puts("\n"
 	    "    Type what you hear!\n"
@@ -362,7 +363,7 @@ teach(void)
 		l = 0;
 		for (i = 0; i < nactive; i++)
 			l += basemul * overall + failprob[i];
-		x = l * ((double)arc4random() / UINT32_MAX);
+		x = l * rand() / RAND_MAX;
 		assert(nactive > 1);
 		for (i = 0; i < nactive - 1; i++) {
 			x -= basemul * overall + failprob[i];
@@ -371,7 +372,7 @@ teach(void)
 		}
 		assert (i < nactive);
 		/* avoid too many direct repeats */
-		if (nactive > 2 && alphabet[i] == ch && arc4random() % 2)
+		if (nactive > 2 && alphabet[i] == ch && rand() <= RAND_MAX/2)
 			continue;
 		ch = alphabet[i];