Signed-off-by: Luis Pires <luis.pi...@eldorado.org.br>
Reviewed-by: Richard Henderson <richard.hender...@linaro.org>
---
include/qemu/host-utils.h | 36 ++++++++++++++++++++++++++++++++++++
1 file changed, 36 insertions(+)
diff --git a/include/qemu/host-utils.h b/include/qemu/host-utils.h
index a3a7ced78d..ca979dc6cc 100644
--- a/include/qemu/host-utils.h
+++ b/include/qemu/host-utils.h
@@ -590,6 +590,42 @@ static inline bool umul64_overflow(uint64_t x, uint64_t y,
uint64_t *ret)
#endif
}
+/*
+ * Unsigned 128x64 multiplication.
+ * Returns true if the result got truncated to 128 bits.
+ * Otherwise, returns false and the multiplication result via plow and phigh.
+ */
+static inline bool mulu128(uint64_t *plow, uint64_t *phigh, uint64_t factor)
+{
+#if defined(CONFIG_INT128) && \
+ (__has_builtin(__builtin_mul_overflow) || __GNUC__ >= 5)
+ bool res;
+ __uint128_t r;
+ __uint128_t f = ((__uint128_t)*phigh << 64) | *plow;
+ res = __builtin_mul_overflow(f, factor, &r);
+
+ *plow = r;
+ *phigh = r >> 64;
+
+ return res;
+#else
+ uint64_t dhi = *phigh;
+ uint64_t dlo = *plow;
+ uint64_t ahi;
+ uint64_t blo, bhi;
+
+ if (dhi == 0) {
+ mulu64(plow, phigh, dlo, factor);
+ return false;
+ }
+
+ mulu64(plow, &ahi, dlo, factor);
+ mulu64(&blo, &bhi, dhi, factor);
+
+ return uadd64_overflow(ahi, blo, phigh) || bhi != 0;
+#endif
+}
+
/**
* uadd64_carry - addition with carry-in and carry-out
* @x, @y: addends
--
2.25.1
