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; \
