Copied from Debian.

From: Dave Martin
Subject: "rsc" doesnt exist anymore in thumb2

diff --git a/fixed.h b/fixed.h
index 4b58abf..ba4bc26 100644
--- a/fixed.h
+++ b/fixed.h
@@ -275,12 +275,25 @@ mad_fixed_t mad_f_mul_inline(mad_fixed_t x, mad_fixed_t y)
 	 : "+r" (lo), "+r" (hi)  \
 	 : "%r" (x), "r" (y))
 
+#ifdef __thumb__
+/* In Thumb-2, the RSB-immediate instruction is only allowed with a zero
+	operand.  If needed this code can also support Thumb-1 
+	(simply append "s" to the end of the second two instructions). */
+#  define MAD_F_MLN(hi, lo)  \
+    asm ("rsbs        %0, %0, #0\n\t"  \
+	 "sbc   %1, %1, %1\n\t"  \
+	 "sub   %1, %1, %2"  \
+	 : "+&r" (lo), "=&r" (hi)  \
+	 : "r" (hi)  \
+	 : "cc")
+#else /* ! __thumb__ */
 #  define MAD_F_MLN(hi, lo)  \
     asm ("rsbs	%0, %2, #0\n\t"  \
 	 "rsc	%1, %3, #0"  \
-	 : "=r" (lo), "=r" (hi)  \
+	 : "=&r" (lo), "=r" (hi)  \
 	 : "0" (lo), "1" (hi)  \
 	 : "cc")
+#endif /* __thumb__ */
 
 #  define mad_f_scale64(hi, lo)  \
     ({ mad_fixed_t __result;  \
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<div class='path'>path: <a href='/guix/log/?id=c880c50019e39604a1444bbc5114e4652dbcaff1'>root</a>/<a href='/guix/log/doc?id=c880c50019e39604a1444bbc5114e4652dbcaff1'>doc</a>/<a href='/guix/log/doc/he-config-bare-bones.scm?id=c880c50019e39604a1444bbc5114e4652dbcaff1'>he-config-bare-bones.scm</a></div><div class='content'><table class='list nowrap'><tr class='nohover'><th class='left'>Age</th><th class='left'>Commit message (<a href='/guix/log/doc/he-config-bare-bones.scm?id=c880c50019e39604a1444bbc5114e4652dbcaff1&amp;showmsg=1'>Expand</a>)</th><th class='left'>Author</th></tr>
<tr><td><span title='2022-06-10 22:42:49 +0200'>2022-06-10</span></td><td><a href='/guix/commit/doc/he-config-bare-bones.scm?id=d859d8873ceb3c591210968cfd4c88e26fc89edc'>doc: Update example of a minimalistic home environment.</a><span class='msg-avail'>...<span class='msg-tooltip'>* doc/he-config-bare-bones.scm: Adujst example according to changes in
bash-service-type and home-files-service-type.

Signed-off-by: Ludovic Courtès &lt;ludo@gnu.org&gt;
</span></span></td><td>Andrew Tropin</td></tr>
<tr><td><span title='2021-10-09 19:24:18 +0300'>2021-10-09</span></td><td><a href='/guix/commit/doc/he-config-bare-bones.scm?id=0e8d2df0f1a4ab25c482e1c427c54e19903e62f3'>Move (gnu home-services) to (gnu home services).</a><span class='msg-avail'>...<span class='msg-tooltip'>* gnu/home-services.scm (%guix-home-root-directory): Replace
gnu/home-services.scm with "gnu/home/services.scm".
Rename to gnu/home/services.scm.
* gnu/local.mk
(GNU_SYSTEM_MODULES): Rename gnu/home-services.scm to gnu/home/services.scm.
* doc/he-config-bare-bones.scm:
Replace (gnu home-services) with (gnu home services).
* gnu/home.scm: Same.
* gnu/home/services/fontutils.scm: Same.
* gnu/home/services/mcron.scm: Same.
* gnu/home/services/shells.scm: Same.
* gnu/home/services/shepherd.scm: Same.
* gnu/home/services/symlink-manager.scm: Same.
* gnu/home/services/xdg.scm: Same.
* guix/scripts/home.scm: Same.
* guix/self.scm: Same.
</span></span></td><td>Oleg Pykhalov</td></tr>
<tr><td><span title='2021-10-08 15:36:18 +0300'>2021-10-08</span></td><td><a href='/guix/commit/doc/he-config-bare-bones.scm?id=ba8ddb348045f81f061a1c7f51c0f7c2b0024e71'>gnu: Move (gnu home-services) to (gnu home services).</a><span class='msg-avail'>...<span class='msg-tooltip'>* gnu/home-services/configuration.scm: Move the content ...
* gnu/home/services/configuration.scm: ... here.
* doc/guix.texi:
Replace (gnu home-services mcron) with (gnu home services mcron).
Replace (gnu home-services) with (gnu home services).
* gnu/home.scm:
Replace (gnu home-services fontutils) with (gnu services fontutils).
Replace (gnu home-services shells) with (gnu home services shells).
Replace (gnu home-services symlink-manager) with
(gnu home services symlink-manager).
Replace (gnu home-services xdg) with (gnu home services xdg).
* gnu/home-services/fontutils.scm: Rename to gnu/services/fontutils.scm.
* gnu/home-services/mcron.scm: Move to gnu/home/services/mcron.scm.
Replace (gnu home-services shepherd) with (gnu home services shepherd).
* gnu/home-services.scm (%service-type-path):
Search home services in "gnu/services".
* gnu/home-services/shells.scm: Replace (gnu home-services configuration) with
(gnu home services configuration).
Rename to gnu/home/services/shells.scm.
Replace (gnu home-services utils) with (gnu home services utils).
* gnu/home-services/shepherd.scm: Move to gnu/home/services/shepherd.scm.
* gnu/home-services/symlink-manager.scm:
Rename to gnu/home/services/symlink-manager.scm.
* gnu/home-services/utils.scm: Rename to gnu/home/services/utils.scm.
* gnu/home-services/xdg.scm: Rename to gnu/home/services/xdg.scm.
* guix/scripts/home/import.scm:
Replace (gnu home-services bash) with (gnu home services bash).
* gnu/home-services.scm: Update documentation string.
* doc/he-config-bare-bones.scm:
Apply new (gnu home-services ...) modules location.
* gnu/local.mk (GNU_SYSTEM_MODULES): Same.
</span></span></td><td>Oleg Pykhalov</td></tr>
<tr><td><span title='2021-09-09 20:26:51 +0300'>2021-09-09</span></td><td><a href='/guix/commit/doc/he-config-bare-bones.scm?id=aaffa43c1752e062934580f55616e0380963a1be'>doc: Add Guix Home documentation.</a><span class='msg-avail'>...<span class='msg-tooltip'>* doc/guix.texi: Add Guix Home documentation.
* doc/he-config-bare-bones.scm: New file.

Signed-off-by: Oleg Pykhalov &lt;go.wigust@gmail.com&gt;
</span></span></td><td>Andrew Tropin</td></tr>