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=397ea21db2c6bb9d5cc589cdc834b07fffe503fc'>root</a>/<a href='/guix/log/tests?id=397ea21db2c6bb9d5cc589cdc834b07fffe503fc'>tests</a>/<a href='/guix/log/tests/cve.scm?id=397ea21db2c6bb9d5cc589cdc834b07fffe503fc'>cve.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/tests/cve.scm?id=397ea21db2c6bb9d5cc589cdc834b07fffe503fc&amp;showmsg=1'>Expand</a>)</th><th class='left'>Author</th></tr>
<tr><td><span title='2019-10-23 16:40:17 +0200'>2019-10-23</span></td><td><a href='/guix/commit/tests/cve.scm?id=74afaa37d5dec1a9d1b83951529ba69d8947fb07'>cve: Rewrite to read the JSON feed instead of the XML feed.</a><span class='msg-avail'>...<span class='msg-tooltip'>The XML feed was discontinued on Oct. 16th, 2019:

  &lt;https://nvd.nist.gov/General/News/XML-Vulnerability-Feed-Retirement-Phase-3&gt;

* guix/cve.scm (string-&gt;date*): New procedure.
(&lt;cve-item&gt;, &lt;cve&gt;, &lt;cve-reference&gt;): New record types.
(cpe-match-&gt;cve-configuration, configuration-data-&gt;cve-configurations)
(json-&gt;cve-items, version-matches?): New procedures.
(yearly-feed-uri): Change URL to refer to JSON feed.
(cpe-&gt;product-alist, %parse-vulnerability-feed)
(xml-&gt;vulnerabilities): Remove.
(cve-configuration-&gt;package-list, merge-package-lists)
(cve-item-&gt;vulnerability, json-&gt;vulnerabilities): New procedures.
(write-cache): Use 'json-&gt;vulnerabilities' instead of
'xml-&gt;vulnerabilities', and remove 'parameterize'.
(vulnerabilities-&gt;lookup-proc): Use 'version-matches?' when VERSION is
true.
* tests/cve.scm (%sample): Use 'tests/cve-sample.json'.
(%expected-vulnerabilities): Rewrite accordingly.
("json-&gt;cve-items", "cve-item-published-date")
("json-&gt;vulnerabilities"): New tests.
("xml-&gt;vulnerabilities"): Remove.
("vulnerabilities-&gt;lookup-proc"): Adjust to new vulnerabilities.
* tests/cve-sample.json: New file.
* tests/cve-sample.xml: Remove.
* Makefile.am (EXTRA_DIST): Adjust accordingly.
* doc/guix.texi (Invoking guix lint): Update nist.gov URLs.
</span></span></td><td>Ludovic Courtès</td></tr>
<tr><td><span title='2019-10-20 23:26:50 +0200'>2019-10-20</span></td><td><a href='/guix/commit/tests/cve.scm?id=79c03e55e26d88c8d327daced02367abe7f17f91'>tests: Avoid now-deprecated 'make-struct'.</a><span class='msg-avail'>...<span class='msg-tooltip'>* tests/cve.scm (vulnerability): Use 'make-struct/no-tail' instead of
'make-struct', which is deprecated.
* tests/lint.scm ("cve: one vulnerability")
("cve: one patched vulnerability")
("cve: known safe from vulnerability")
("cve: vulnerability fixed in replacement version")
("cve: patched vulnerability in replacement"): Likewise.
</span></span></td><td>Ludovic Courtès</td></tr>