math: move x87-family remainder functions to C with inline asm

1 files changed, 12 insertions, 0 deletions

diff --git a/src/math/i386/remainder.c b/src/math/i386/remainder.c
new file mode 100644
index 00000000..c083df90
--- /dev/null
+++ b/src/math/i386/remainder.c
@@ -0,0 +1,12 @@
+#include <math.h>
+
+double remainder(double x, double y)
+{
+	unsigned short fpsr;
+	// fprem1 does not introduce excess precision into x
+	do __asm__ ("fprem1; fnstsw %%ax" : "+t"(x), "=a"(fpsr) : "u"(y));
+	while (fpsr & 0x400);
+	return x;
+}
+
+weak_alias(remainder, drem);