diff mbox series

[Stable-7.2.7,02/62] host-utils: Add muldiv64_round_up

Message ID 20231109135933.1462615-2-mjt@tls.msk.ru (mailing list archive)
State New, archived
Headers show
Series Patch Round-up for stable 7.2.7, freeze on 2023-11-19 | expand

Commit Message

Michael Tokarev Nov. 9, 2023, 1:58 p.m. UTC 
From: Nicholas Piggin <npiggin@gmail.com>

This will be used for converting time intervals in different base units
to host units, for the purpose of scheduling timers to emulate target
timers. Timers typically must not fire before their requested expiry
time but may fire some time afterward, so rounding up is the right way
to implement these.

Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
[ clg: renamed __muldiv64() to muldiv64_rounding() ]
Signed-off-by: Cédric Le Goater <clg@kaod.org>
(cherry picked from commit 47de6c4c287079744ceb96f606b3c0457addf380)
Signed-off-by: Michael Tokarev <mjt@tls.msk.ru>
diff mbox series

Patch

diff --git a/include/qemu/host-utils.h b/include/qemu/host-utils.h
index b3434ec0bc..09daf58787 100644
--- a/include/qemu/host-utils.h
+++ b/include/qemu/host-utils.h
@@ -57,6 +57,11 @@  static inline uint64_t muldiv64(uint64_t a, uint32_t b, uint32_t c)
     return (__int128_t)a * b / c;
 }
 
+static inline uint64_t muldiv64_round_up(uint64_t a, uint32_t b, uint32_t c)
+{
+    return ((__int128_t)a * b + c - 1) / c;
+}
+
 static inline uint64_t divu128(uint64_t *plow, uint64_t *phigh,
                                uint64_t divisor)
 {
@@ -84,7 +89,8 @@  void mulu64(uint64_t *plow, uint64_t *phigh, uint64_t a, uint64_t b);
 uint64_t divu128(uint64_t *plow, uint64_t *phigh, uint64_t divisor);
 int64_t divs128(uint64_t *plow, int64_t *phigh, int64_t divisor);
 
-static inline uint64_t muldiv64(uint64_t a, uint32_t b, uint32_t c)
+static inline uint64_t muldiv64_rounding(uint64_t a, uint32_t b, uint32_t c,
+                                  bool round_up)
 {
     union {
         uint64_t ll;
@@ -100,12 +106,25 @@  static inline uint64_t muldiv64(uint64_t a, uint32_t b, uint32_t c)
 
     u.ll = a;
     rl = (uint64_t)u.l.low * (uint64_t)b;
+    if (round_up) {
+        rl += c - 1;
+    }
     rh = (uint64_t)u.l.high * (uint64_t)b;
     rh += (rl >> 32);
     res.l.high = rh / c;
     res.l.low = (((rh % c) << 32) + (rl & 0xffffffff)) / c;
     return res.ll;
 }
+
+static inline uint64_t muldiv64(uint64_t a, uint32_t b, uint32_t c)
+{
+    return muldiv64_rounding(a, b, c, false);
+}
+
+static inline uint64_t muldiv64_round_up(uint64_t a, uint32_t b, uint32_t c)
+{
+    return muldiv64_rounding(a, b, c, true);
+}
 #endif
 
 /**