From aecba4b2f64096cbc7bf32d1fa50f827877bb0f5 Mon Sep 17 00:00:00 2001
From: Philipp Hoffmann <Philipp.Hoffmann@protonmail.com>
Date: Mon, 25 Mar 2024 00:20:40 +0100
Subject: [PATCH 01/22] faster ifrac

---
 pandas/_libs/src/vendored/numpy/datetime/np_datetime.c | 7 ++-----
 1 file changed, 2 insertions(+), 5 deletions(-)

diff --git a/pandas/_libs/src/vendored/numpy/datetime/np_datetime.c b/pandas/_libs/src/vendored/numpy/datetime/np_datetime.c
index f854f7b9210d8..329331f59e598 100644
--- a/pandas/_libs/src/vendored/numpy/datetime/np_datetime.c
+++ b/pandas/_libs/src/vendored/numpy/datetime/np_datetime.c
@@ -761,6 +761,7 @@ void pandas_timedelta_to_timedeltastruct(npy_timedelta td,
 
     const int sign = frac < 0 ? -1 : 1;
     if (frac < 0) {
+    npy_int64 ifrac = td;
       // even fraction
       if ((-frac % sec_per_day) != 0) {
         out->days = -frac / sec_per_day + 1;
@@ -794,11 +795,7 @@ void pandas_timedelta_to_timedeltastruct(npy_timedelta td,
       out->days = -out->days;
 
     if (base > NPY_FR_s) {
-      const npy_int64 sfrac =
-          (out->hrs * sec_per_hour + out->min * sec_per_min + out->sec) *
-          per_sec;
-
-      npy_int64 ifrac = td - (out->days * per_day + sfrac);
+      ifrac = (ifrac - out->days * per_day) % per_sec;
 
       if (base == NPY_FR_ms) {
         out->ms = (npy_int32)ifrac;

From 6f43de0263ed1ae9654cd8996ae4eb68408f2f9a Mon Sep 17 00:00:00 2001
From: Philipp Hoffmann <Philipp.Hoffmann@protonmail.com>
Date: Mon, 25 Mar 2024 00:22:02 +0100
Subject: [PATCH 02/22] remove unnecessary statement

---
 pandas/_libs/src/vendored/numpy/datetime/np_datetime.c | 1 -
 1 file changed, 1 deletion(-)

diff --git a/pandas/_libs/src/vendored/numpy/datetime/np_datetime.c b/pandas/_libs/src/vendored/numpy/datetime/np_datetime.c
index 329331f59e598..7262d4c6f4677 100644
--- a/pandas/_libs/src/vendored/numpy/datetime/np_datetime.c
+++ b/pandas/_libs/src/vendored/numpy/datetime/np_datetime.c
@@ -788,7 +788,6 @@ void pandas_timedelta_to_timedeltastruct(npy_timedelta td,
 
     if (frac >= 0) {
       out->sec = (npy_int32)frac;
-      frac -= out->sec;
     }
 
     if (sign < 0)

From 47a0d9b36aa237be7094ab59a356b0a9cf6cf752 Mon Sep 17 00:00:00 2001
From: Philipp Hoffmann <Philipp.Hoffmann@protonmail.com>
Date: Mon, 25 Mar 2024 00:24:05 +0100
Subject: [PATCH 03/22] shorten <s assignment

---
 .../_libs/src/vendored/numpy/datetime/np_datetime.c | 13 +++++++------
 1 file changed, 7 insertions(+), 6 deletions(-)

diff --git a/pandas/_libs/src/vendored/numpy/datetime/np_datetime.c b/pandas/_libs/src/vendored/numpy/datetime/np_datetime.c
index 7262d4c6f4677..a050ea3c09aaa 100644
--- a/pandas/_libs/src/vendored/numpy/datetime/np_datetime.c
+++ b/pandas/_libs/src/vendored/numpy/datetime/np_datetime.c
@@ -797,19 +797,20 @@ void pandas_timedelta_to_timedeltastruct(npy_timedelta td,
       ifrac = (ifrac - out->days * per_day) % per_sec;
 
       if (base == NPY_FR_ms) {
-        out->ms = (npy_int32)ifrac;
+        out->ms = ifrac;
       } else if (base == NPY_FR_us) {
         out->ms = (npy_int32)(ifrac / 1000LL);
         ifrac = ifrac % 1000LL;
         out->us = (npy_int32)ifrac;
+        out->ms = (ifrac / 1000LL);
+        out->us = ifrac % 1000LL;
       } else if (base == NPY_FR_ns) {
-        out->ms = (npy_int32)(ifrac / (1000LL * 1000LL));
-        ifrac = ifrac % (1000LL * 1000LL);
-        out->us = (npy_int32)(ifrac / 1000LL);
-        ifrac = ifrac % 1000LL;
-        out->ns = (npy_int32)ifrac;
+        out->ms = (ifrac / (1000LL * 1000LL));
+        out->us = (ifrac / 1000LL);
+        out->nanoseconds = ifrac % 1000LL;
       }
     }
+    out->microseconds = out->ms * 1000 + out->us;
 
   } break;
   default:

From 61c5caee073588fec9b0f1d5a3612fd1b90c8f99 Mon Sep 17 00:00:00 2001
From: Philipp Hoffmann <Philipp.Hoffmann@protonmail.com>
Date: Mon, 25 Mar 2024 00:24:40 +0100
Subject: [PATCH 04/22] remove assignments

---
 pandas/_libs/src/vendored/numpy/datetime/np_datetime.c | 3 ---
 1 file changed, 3 deletions(-)

diff --git a/pandas/_libs/src/vendored/numpy/datetime/np_datetime.c b/pandas/_libs/src/vendored/numpy/datetime/np_datetime.c
index a050ea3c09aaa..c8ef857fc7140 100644
--- a/pandas/_libs/src/vendored/numpy/datetime/np_datetime.c
+++ b/pandas/_libs/src/vendored/numpy/datetime/np_datetime.c
@@ -799,9 +799,6 @@ void pandas_timedelta_to_timedeltastruct(npy_timedelta td,
       if (base == NPY_FR_ms) {
         out->ms = ifrac;
       } else if (base == NPY_FR_us) {
-        out->ms = (npy_int32)(ifrac / 1000LL);
-        ifrac = ifrac % 1000LL;
-        out->us = (npy_int32)ifrac;
         out->ms = (ifrac / 1000LL);
         out->us = ifrac % 1000LL;
       } else if (base == NPY_FR_ns) {

From e4c64b271e0215251c4907bf7028cfe27aeb33d4 Mon Sep 17 00:00:00 2001
From: Philipp Hoffmann <Philipp.Hoffmann@protonmail.com>
Date: Mon, 25 Mar 2024 00:25:15 +0100
Subject: [PATCH 05/22] shorten frac assignments

---
 pandas/_libs/src/vendored/numpy/datetime/np_datetime.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/pandas/_libs/src/vendored/numpy/datetime/np_datetime.c b/pandas/_libs/src/vendored/numpy/datetime/np_datetime.c
index c8ef857fc7140..cd0e238707d78 100644
--- a/pandas/_libs/src/vendored/numpy/datetime/np_datetime.c
+++ b/pandas/_libs/src/vendored/numpy/datetime/np_datetime.c
@@ -778,12 +778,12 @@ void pandas_timedelta_to_timedeltastruct(npy_timedelta td,
 
     if (frac >= sec_per_hour) {
       out->hrs = (npy_int32)(frac / sec_per_hour);
-      frac -= out->hrs * sec_per_hour;
+      frac %= sec_per_hour;
     }
 
     if (frac >= sec_per_min) {
       out->min = (npy_int32)(frac / sec_per_min);
-      frac -= out->min * sec_per_min;
+      frac %= sec_per_min;
     }
 
     if (frac >= 0) {

From fa3ff63789236e2e0618854c417b29d6cbf9f5a6 Mon Sep 17 00:00:00 2001
From: Philipp Hoffmann <Philipp.Hoffmann@protonmail.com>
Date: Mon, 25 Mar 2024 00:25:52 +0100
Subject: [PATCH 06/22] shorten days logic

---
 .../src/vendored/numpy/datetime/np_datetime.c | 32 ++++++++-----------
 1 file changed, 13 insertions(+), 19 deletions(-)

diff --git a/pandas/_libs/src/vendored/numpy/datetime/np_datetime.c b/pandas/_libs/src/vendored/numpy/datetime/np_datetime.c
index cd0e238707d78..aad129f056511 100644
--- a/pandas/_libs/src/vendored/numpy/datetime/np_datetime.c
+++ b/pandas/_libs/src/vendored/numpy/datetime/np_datetime.c
@@ -752,28 +752,25 @@ void pandas_timedelta_to_timedeltastruct(npy_timedelta td,
     }
 
     const npy_int64 per_day = sec_per_day * per_sec;
-    npy_int64 frac;
-    // put frac in seconds
-    if (td < 0 && td % per_sec != 0)
-      frac = td / per_sec - 1;
-    else
-      frac = td / per_sec;
-
-    const int sign = frac < 0 ? -1 : 1;
-    if (frac < 0) {
     npy_int64 ifrac = td;
+    int sign = td >= 0 ? 1 : -1;
+    int has_seconds = td % per_sec != 0 ? 1 : 0;
+    frac = td / per_sec;
+    if (sign < 0) {
+      if (has_seconds == 1) {
+        frac -= 1;
+      }
+      frac *= -1;
       // even fraction
-      if ((-frac % sec_per_day) != 0) {
-        out->days = -frac / sec_per_day + 1;
-        frac += sec_per_day * out->days;
-      } else {
-        frac = -frac;
+      if ((frac % sec_per_day) != 0) {
+        out->days = -frac / sec_per_day - 1;
+        frac += per_sec * out->days;
       }
     }
 
     if (frac >= sec_per_day) {
-      out->days += frac / sec_per_day;
-      frac -= out->days * sec_per_day;
+      out->days += sign * frac / sec_per_day;
+      frac -= sign * out->days * sec_per_day;
     }
 
     if (frac >= sec_per_hour) {
@@ -790,9 +787,6 @@ void pandas_timedelta_to_timedeltastruct(npy_timedelta td,
       out->sec = (npy_int32)frac;
     }
 
-    if (sign < 0)
-      out->days = -out->days;
-
     if (base > NPY_FR_s) {
       ifrac = (ifrac - out->days * per_day) % per_sec;
 

From 9d768d6987e2b0821eb69ee8cdf5f712d896dd08 Mon Sep 17 00:00:00 2001
From: Philipp Hoffmann <Philipp.Hoffmann@protonmail.com>
Date: Mon, 25 Mar 2024 00:26:54 +0100
Subject: [PATCH 07/22] remove unnecessary assignments

---
 pandas/_libs/src/vendored/numpy/datetime/np_datetime.c | 2 --
 1 file changed, 2 deletions(-)

diff --git a/pandas/_libs/src/vendored/numpy/datetime/np_datetime.c b/pandas/_libs/src/vendored/numpy/datetime/np_datetime.c
index aad129f056511..fb6534071efb3 100644
--- a/pandas/_libs/src/vendored/numpy/datetime/np_datetime.c
+++ b/pandas/_libs/src/vendored/numpy/datetime/np_datetime.c
@@ -813,8 +813,6 @@ void pandas_timedelta_to_timedeltastruct(npy_timedelta td,
 
   out->seconds =
       (npy_int32)(out->hrs * sec_per_hour + out->min * sec_per_min + out->sec);
-  out->microseconds = out->ms * 1000 + out->us;
-  out->nanoseconds = out->ns;
 }
 
 /*

From c9f75b1b33411e5e8400e898e04797a89dce66ae Mon Sep 17 00:00:00 2001
From: Philipp Hoffmann <Philipp.Hoffmann@protonmail.com>
Date: Mon, 25 Mar 2024 00:29:16 +0100
Subject: [PATCH 08/22] reuse td

---
 .../src/vendored/numpy/datetime/np_datetime.c | 34 +++++++++----------
 1 file changed, 17 insertions(+), 17 deletions(-)

diff --git a/pandas/_libs/src/vendored/numpy/datetime/np_datetime.c b/pandas/_libs/src/vendored/numpy/datetime/np_datetime.c
index fb6534071efb3..4328e0a2cd68a 100644
--- a/pandas/_libs/src/vendored/numpy/datetime/np_datetime.c
+++ b/pandas/_libs/src/vendored/numpy/datetime/np_datetime.c
@@ -755,36 +755,36 @@ void pandas_timedelta_to_timedeltastruct(npy_timedelta td,
     npy_int64 ifrac = td;
     int sign = td >= 0 ? 1 : -1;
     int has_seconds = td % per_sec != 0 ? 1 : 0;
-    frac = td / per_sec;
+    td = td / per_sec;
     if (sign < 0) {
       if (has_seconds == 1) {
-        frac -= 1;
+        td -= 1;
       }
-      frac *= -1;
+      td *= -1;
       // even fraction
-      if ((frac % sec_per_day) != 0) {
-        out->days = -frac / sec_per_day - 1;
-        frac += per_sec * out->days;
+      if ((td % sec_per_day) != 0) {
+        out->days = -td / sec_per_day - 1;
+        td += per_sec * out->days;
       }
     }
 
-    if (frac >= sec_per_day) {
-      out->days += sign * frac / sec_per_day;
-      frac -= sign * out->days * sec_per_day;
+    if (td >= sec_per_day) {
+      out->days += sign * td / sec_per_day;
+      td -= sign * out->days * sec_per_day;
     }
 
-    if (frac >= sec_per_hour) {
-      out->hrs = (npy_int32)(frac / sec_per_hour);
-      frac %= sec_per_hour;
+    if (td >= sec_per_hour) {
+      out->hrs = (npy_int32)(td / sec_per_hour);
+      td %= sec_per_hour;
     }
 
-    if (frac >= sec_per_min) {
-      out->min = (npy_int32)(frac / sec_per_min);
-      frac %= sec_per_min;
+    if (td >= sec_per_min) {
+      out->min = (npy_int32)(td / sec_per_min);
+      td %= sec_per_min;
     }
 
-    if (frac >= 0) {
-      out->sec = (npy_int32)frac;
+    if (td >= 0) {
+      out->sec = (npy_int32)td;
     }
 
     if (base > NPY_FR_s) {

From aba6c3a777e28e2014435551fb4b73d6ac581633 Mon Sep 17 00:00:00 2001
From: Philipp Hoffmann <Philipp.Hoffmann@protonmail.com>
Date: Mon, 25 Mar 2024 02:15:46 +0100
Subject: [PATCH 09/22] fix regression for td close to int64 bounds

---
 .../src/vendored/numpy/datetime/np_datetime.c | 49 +++++++++++--------
 1 file changed, 28 insertions(+), 21 deletions(-)

diff --git a/pandas/_libs/src/vendored/numpy/datetime/np_datetime.c b/pandas/_libs/src/vendored/numpy/datetime/np_datetime.c
index 4328e0a2cd68a..e943f8cafa376 100644
--- a/pandas/_libs/src/vendored/numpy/datetime/np_datetime.c
+++ b/pandas/_libs/src/vendored/numpy/datetime/np_datetime.c
@@ -753,55 +753,63 @@ void pandas_timedelta_to_timedeltastruct(npy_timedelta td,
 
     const npy_int64 per_day = sec_per_day * per_sec;
     npy_int64 ifrac = td;
-    int sign = td >= 0 ? 1 : -1;
-    int has_seconds = td % per_sec != 0 ? 1 : 0;
-    td = td / per_sec;
-    if (sign < 0) {
-      if (has_seconds == 1) {
-        td -= 1;
-      }
-      td *= -1;
+    const int sign = td < 0 ? -1 : 1;
+    // put frac in seconds
+    if (sign < 0 && td % per_sec != 0)
+      td = td / per_sec - 1;
+    else
+      td = td / per_sec;
+
+    if (td < 0) {
       // even fraction
-      if ((td % sec_per_day) != 0) {
-        out->days = -td / sec_per_day - 1;
-        td += per_sec * out->days;
+      if ((-td % sec_per_day) != 0) {
+        out->days = -td / sec_per_day + 1;
+        td += sec_per_day * out->days;
+      } else {
+        td = -td;
       }
     }
 
     if (td >= sec_per_day) {
-      out->days += sign * td / sec_per_day;
-      td -= sign * out->days * sec_per_day;
+      out->days += td / sec_per_day;
+      td -= out->days * sec_per_day;
     }
 
     if (td >= sec_per_hour) {
-      out->hrs = (npy_int32)(td / sec_per_hour);
+      out->hrs = (td / sec_per_hour);
       td %= sec_per_hour;
     }
 
     if (td >= sec_per_min) {
-      out->min = (npy_int32)(td / sec_per_min);
+      out->min = td / sec_per_min;
       td %= sec_per_min;
     }
 
     if (td >= 0) {
-      out->sec = (npy_int32)td;
+      out->sec = td;
     }
 
+    if (sign < 0)
+      out->days = -out->days;
+
     if (base > NPY_FR_s) {
+      // the days * per_day removes so many base units that ifrac is within
+      // int32 bounds
       ifrac = (ifrac - out->days * per_day) % per_sec;
 
       if (base == NPY_FR_ms) {
         out->ms = ifrac;
       } else if (base == NPY_FR_us) {
-        out->ms = (ifrac / 1000LL);
+        out->ms = ifrac / 1000LL;
         out->us = ifrac % 1000LL;
       } else if (base == NPY_FR_ns) {
-        out->ms = (ifrac / (1000LL * 1000LL));
-        out->us = (ifrac / 1000LL);
+        out->ms = ifrac / (1000LL * 1000LL);
+        ifrac = ifrac % (1000LL * 1000LL);
+        out->us = ifrac / 1000LL;
         out->nanoseconds = ifrac % 1000LL;
       }
+      out->microseconds = out->ms * 1000 + out->us;
     }
-    out->microseconds = out->ms * 1000 + out->us;
 
   } break;
   default:
@@ -810,7 +818,6 @@ void pandas_timedelta_to_timedeltastruct(npy_timedelta td,
                     "invalid base unit");
     break;
   }
-
   out->seconds =
       (npy_int32)(out->hrs * sec_per_hour + out->min * sec_per_min + out->sec);
 }

From e7c02e80007bc9e769abdcb516afcf6a8f499aee Mon Sep 17 00:00:00 2001
From: Philipp Hoffmann <Philipp.Hoffmann@protonmail.com>
Date: Mon, 25 Mar 2024 02:29:54 +0100
Subject: [PATCH 10/22] re-add unnecessary conversions

---
 .../src/vendored/numpy/datetime/np_datetime.c | 20 +++++++++----------
 1 file changed, 9 insertions(+), 11 deletions(-)

diff --git a/pandas/_libs/src/vendored/numpy/datetime/np_datetime.c b/pandas/_libs/src/vendored/numpy/datetime/np_datetime.c
index e943f8cafa376..c4329fef1b59b 100644
--- a/pandas/_libs/src/vendored/numpy/datetime/np_datetime.c
+++ b/pandas/_libs/src/vendored/numpy/datetime/np_datetime.c
@@ -776,37 +776,35 @@ void pandas_timedelta_to_timedeltastruct(npy_timedelta td,
     }
 
     if (td >= sec_per_hour) {
-      out->hrs = (td / sec_per_hour);
+      out->hrs = (npy_int32)(td / sec_per_hour);
       td %= sec_per_hour;
     }
 
     if (td >= sec_per_min) {
-      out->min = td / sec_per_min;
+      out->min = (npy_int32)(td / sec_per_min);
       td %= sec_per_min;
     }
 
     if (td >= 0) {
-      out->sec = td;
+      out->sec = (npy_int32)td;
     }
 
     if (sign < 0)
       out->days = -out->days;
 
     if (base > NPY_FR_s) {
-      // the days * per_day removes so many base units that ifrac is within
-      // int32 bounds
       ifrac = (ifrac - out->days * per_day) % per_sec;
 
       if (base == NPY_FR_ms) {
-        out->ms = ifrac;
+        out->ms = (npy_int32)ifrac;
       } else if (base == NPY_FR_us) {
-        out->ms = ifrac / 1000LL;
-        out->us = ifrac % 1000LL;
+        out->ms = (npy_int32)(ifrac / 1000LL);
+        out->us = (npy_int32)(ifrac % 1000LL);
       } else if (base == NPY_FR_ns) {
-        out->ms = ifrac / (1000LL * 1000LL);
+        out->ms = (npy_int32)(ifrac / (1000LL * 1000LL));
         ifrac = ifrac % (1000LL * 1000LL);
-        out->us = ifrac / 1000LL;
-        out->nanoseconds = ifrac % 1000LL;
+        out->us = (npy_int32)(ifrac / 1000LL);
+        out->nanoseconds = (npy_int32)(ifrac % 1000LL);
       }
       out->microseconds = out->ms * 1000 + out->us;
     }

From b3c0199fd3af31cceb45278751d9be45d35d55ce Mon Sep 17 00:00:00 2001
From: Philipp Hoffmann <Philipp.Hoffmann@protonmail.com>
Date: Mon, 25 Mar 2024 22:12:17 +0100
Subject: [PATCH 11/22] remove sign if

---
 pandas/_libs/src/vendored/numpy/datetime/np_datetime.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/pandas/_libs/src/vendored/numpy/datetime/np_datetime.c b/pandas/_libs/src/vendored/numpy/datetime/np_datetime.c
index c4329fef1b59b..15985224898de 100644
--- a/pandas/_libs/src/vendored/numpy/datetime/np_datetime.c
+++ b/pandas/_libs/src/vendored/numpy/datetime/np_datetime.c
@@ -754,8 +754,9 @@ void pandas_timedelta_to_timedeltastruct(npy_timedelta td,
     const npy_int64 per_day = sec_per_day * per_sec;
     npy_int64 ifrac = td;
     const int sign = td < 0 ? -1 : 1;
+    const int uneven_in_seconds = td % per_sec != 0;
     // put frac in seconds
-    if (sign < 0 && td % per_sec != 0)
+    if (sign < 0 && uneven_in_seconds)
       td = td / per_sec - 1;
     else
       td = td / per_sec;
@@ -775,6 +776,8 @@ void pandas_timedelta_to_timedeltastruct(npy_timedelta td,
       td -= out->days * sec_per_day;
     }
 
+    out->days = sign * (out->days);
+
     if (td >= sec_per_hour) {
       out->hrs = (npy_int32)(td / sec_per_hour);
       td %= sec_per_hour;

From 5a04d8dedd00815299dff81201111edb45cdf43c Mon Sep 17 00:00:00 2001
From: Philipp Hoffmann <Philipp.Hoffmann@protonmail.com>
Date: Mon, 25 Mar 2024 22:23:07 +0100
Subject: [PATCH 12/22] remove mod seconds if layer

---
 .../src/vendored/numpy/datetime/np_datetime.c | 26 +++++++++----------
 1 file changed, 13 insertions(+), 13 deletions(-)

diff --git a/pandas/_libs/src/vendored/numpy/datetime/np_datetime.c b/pandas/_libs/src/vendored/numpy/datetime/np_datetime.c
index 15985224898de..751c8c6d386eb 100644
--- a/pandas/_libs/src/vendored/numpy/datetime/np_datetime.c
+++ b/pandas/_libs/src/vendored/numpy/datetime/np_datetime.c
@@ -754,21 +754,21 @@ void pandas_timedelta_to_timedeltastruct(npy_timedelta td,
     const npy_int64 per_day = sec_per_day * per_sec;
     npy_int64 ifrac = td;
     const int sign = td < 0 ? -1 : 1;
-    const int uneven_in_seconds = td % per_sec != 0;
+    const int uneven_in_seconds = td % per_sec != 0 ? 1 : 0;
     // put frac in seconds
-    if (sign < 0 && uneven_in_seconds)
-      td = td / per_sec - 1;
-    else
-      td = td / per_sec;
-
-    if (td < 0) {
-      // even fraction
-      if ((-td % sec_per_day) != 0) {
-        out->days = -td / sec_per_day + 1;
-        td += sec_per_day * out->days;
-      } else {
-        td = -td;
+    if (sign < 0) {
+      td = td / per_sec - uneven_in_seconds;
+      if (td < 0) {
+        // even fraction
+        if ((-td % sec_per_day) != 0) {
+          out->days = -td / sec_per_day + 1;
+          td += sec_per_day * out->days;
+        } else {
+          td = -td;
+        }
       }
+    } else {
+      td = td / per_sec;
     }
 
     if (td >= sec_per_day) {

From 39c77ab7cf3aea11864d15e7d7053f8d5f3ef03d Mon Sep 17 00:00:00 2001
From: Philipp Hoffmann <Philipp.Hoffmann@protonmail.com>
Date: Mon, 25 Mar 2024 22:24:44 +0100
Subject: [PATCH 13/22] remove second negative check if layer

---
 .../src/vendored/numpy/datetime/np_datetime.c      | 14 ++++++--------
 1 file changed, 6 insertions(+), 8 deletions(-)

diff --git a/pandas/_libs/src/vendored/numpy/datetime/np_datetime.c b/pandas/_libs/src/vendored/numpy/datetime/np_datetime.c
index 751c8c6d386eb..660180f4a884e 100644
--- a/pandas/_libs/src/vendored/numpy/datetime/np_datetime.c
+++ b/pandas/_libs/src/vendored/numpy/datetime/np_datetime.c
@@ -758,14 +758,12 @@ void pandas_timedelta_to_timedeltastruct(npy_timedelta td,
     // put frac in seconds
     if (sign < 0) {
       td = td / per_sec - uneven_in_seconds;
-      if (td < 0) {
-        // even fraction
-        if ((-td % sec_per_day) != 0) {
-          out->days = -td / sec_per_day + 1;
-          td += sec_per_day * out->days;
-        } else {
-          td = -td;
-        }
+      // even fraction
+      if ((-td % sec_per_day) != 0) {
+        out->days = -td / sec_per_day + 1;
+        td += sec_per_day * out->days;
+      } else {
+        td = -td;
       }
     } else {
       td = td / per_sec;

From 2227b1b4fe269e1fefde15dee37143ef0d73f026 Mon Sep 17 00:00:00 2001
From: Philipp Hoffmann <Philipp.Hoffmann@protonmail.com>
Date: Mon, 25 Mar 2024 22:28:52 +0100
Subject: [PATCH 14/22] duplicate larger than day check

---
 pandas/_libs/src/vendored/numpy/datetime/np_datetime.c | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/pandas/_libs/src/vendored/numpy/datetime/np_datetime.c b/pandas/_libs/src/vendored/numpy/datetime/np_datetime.c
index 660180f4a884e..b20ee10fb127f 100644
--- a/pandas/_libs/src/vendored/numpy/datetime/np_datetime.c
+++ b/pandas/_libs/src/vendored/numpy/datetime/np_datetime.c
@@ -765,8 +765,17 @@ void pandas_timedelta_to_timedeltastruct(npy_timedelta td,
       } else {
         td = -td;
       }
+      if (td >= sec_per_day) {
+        out->days += out->days + td / sec_per_day;
+        td -= out->days * sec_per_day;
+      }
+      out->days = -out->days;
     } else {
       td = td / per_sec;
+      if (td >= sec_per_day) {
+        out->days += out->days + td / sec_per_day;
+        td -= out->days * sec_per_day;
+      }
     }
 
     if (td >= sec_per_day) {

From 0171a7c3a98ed1a884676c9af55e5f505bb1382f Mon Sep 17 00:00:00 2001
From: Philipp Hoffmann <Philipp.Hoffmann@protonmail.com>
Date: Mon, 25 Mar 2024 22:30:03 +0100
Subject: [PATCH 15/22] remove forgetten functions

---
 pandas/_libs/src/vendored/numpy/datetime/np_datetime.c | 10 ----------
 1 file changed, 10 deletions(-)

diff --git a/pandas/_libs/src/vendored/numpy/datetime/np_datetime.c b/pandas/_libs/src/vendored/numpy/datetime/np_datetime.c
index b20ee10fb127f..90e068b31ec0e 100644
--- a/pandas/_libs/src/vendored/numpy/datetime/np_datetime.c
+++ b/pandas/_libs/src/vendored/numpy/datetime/np_datetime.c
@@ -778,13 +778,6 @@ void pandas_timedelta_to_timedeltastruct(npy_timedelta td,
       }
     }
 
-    if (td >= sec_per_day) {
-      out->days += td / sec_per_day;
-      td -= out->days * sec_per_day;
-    }
-
-    out->days = sign * (out->days);
-
     if (td >= sec_per_hour) {
       out->hrs = (npy_int32)(td / sec_per_hour);
       td %= sec_per_hour;
@@ -799,9 +792,6 @@ void pandas_timedelta_to_timedeltastruct(npy_timedelta td,
       out->sec = (npy_int32)td;
     }
 
-    if (sign < 0)
-      out->days = -out->days;
-
     if (base > NPY_FR_s) {
       ifrac = (ifrac - out->days * per_day) % per_sec;
 

From 1492bc91030ffd90a4871c3fcb02646918793348 Mon Sep 17 00:00:00 2001
From: Philipp Hoffmann <Philipp.Hoffmann@protonmail.com>
Date: Mon, 25 Mar 2024 22:35:13 +0100
Subject: [PATCH 16/22] make days assignment conditions explicit

---
 .../_libs/src/vendored/numpy/datetime/np_datetime.c   | 11 ++++++-----
 1 file changed, 6 insertions(+), 5 deletions(-)

diff --git a/pandas/_libs/src/vendored/numpy/datetime/np_datetime.c b/pandas/_libs/src/vendored/numpy/datetime/np_datetime.c
index 90e068b31ec0e..022706b8f5f61 100644
--- a/pandas/_libs/src/vendored/numpy/datetime/np_datetime.c
+++ b/pandas/_libs/src/vendored/numpy/datetime/np_datetime.c
@@ -764,16 +764,17 @@ void pandas_timedelta_to_timedeltastruct(npy_timedelta td,
         td += sec_per_day * out->days;
       } else {
         td = -td;
-      }
-      if (td >= sec_per_day) {
-        out->days += out->days + td / sec_per_day;
-        td -= out->days * sec_per_day;
+        if (td >= sec_per_day) {
+          out->days = td / sec_per_day;
+          td -= out->days * sec_per_day;
+        }
       }
       out->days = -out->days;
+
     } else {
       td = td / per_sec;
       if (td >= sec_per_day) {
-        out->days += out->days + td / sec_per_day;
+        out->days = td / sec_per_day;
         td -= out->days * sec_per_day;
       }
     }

From 2e670c038dfa82fe64514d1a85fc8660f07346e5 Mon Sep 17 00:00:00 2001
From: Philipp Hoffmann <Philipp.Hoffmann@protonmail.com>
Date: Mon, 25 Mar 2024 22:38:57 +0100
Subject: [PATCH 17/22] directly flip out.days

---
 pandas/_libs/src/vendored/numpy/datetime/np_datetime.c | 9 ++++-----
 1 file changed, 4 insertions(+), 5 deletions(-)

diff --git a/pandas/_libs/src/vendored/numpy/datetime/np_datetime.c b/pandas/_libs/src/vendored/numpy/datetime/np_datetime.c
index 022706b8f5f61..22a712d11e92e 100644
--- a/pandas/_libs/src/vendored/numpy/datetime/np_datetime.c
+++ b/pandas/_libs/src/vendored/numpy/datetime/np_datetime.c
@@ -760,16 +760,15 @@ void pandas_timedelta_to_timedeltastruct(npy_timedelta td,
       td = td / per_sec - uneven_in_seconds;
       // even fraction
       if ((-td % sec_per_day) != 0) {
-        out->days = -td / sec_per_day + 1;
-        td += sec_per_day * out->days;
+        out->days = td / sec_per_day - 1;
+        td -= sec_per_day * out->days;
       } else {
         td = -td;
         if (td >= sec_per_day) {
-          out->days = td / sec_per_day;
-          td -= out->days * sec_per_day;
+          out->days = -td / sec_per_day;
+          td += out->days * sec_per_day;
         }
       }
-      out->days = -out->days;
 
     } else {
       td = td / per_sec;

From 03164421b6754de80263292583ffdc232e35eaae Mon Sep 17 00:00:00 2001
From: Philipp Hoffmann <Philipp.Hoffmann@protonmail.com>
Date: Mon, 25 Mar 2024 22:57:10 +0100
Subject: [PATCH 18/22] extract normalization to secs

---
 .../src/vendored/numpy/datetime/np_datetime.c | 22 +++++++++----------
 1 file changed, 11 insertions(+), 11 deletions(-)

diff --git a/pandas/_libs/src/vendored/numpy/datetime/np_datetime.c b/pandas/_libs/src/vendored/numpy/datetime/np_datetime.c
index 22a712d11e92e..2a0cfc4c6bcaf 100644
--- a/pandas/_libs/src/vendored/numpy/datetime/np_datetime.c
+++ b/pandas/_libs/src/vendored/numpy/datetime/np_datetime.c
@@ -756,26 +756,26 @@ void pandas_timedelta_to_timedeltastruct(npy_timedelta td,
     const int sign = td < 0 ? -1 : 1;
     const int uneven_in_seconds = td % per_sec != 0 ? 1 : 0;
     // put frac in seconds
+    td = td / per_sec;
     if (sign < 0) {
-      td = td / per_sec - uneven_in_seconds;
+      td -= uneven_in_seconds;
       // even fraction
       if ((-td % sec_per_day) != 0) {
+        // days = td / sec_per_day - is_even_fraction
         out->days = td / sec_per_day - 1;
         td -= sec_per_day * out->days;
       } else {
-        td = -td;
-        if (td >= sec_per_day) {
-          out->days = -td / sec_per_day;
+        if (td <= sec_per_day) {
+          out->days = td / sec_per_day;
+          td = -td;
           td += out->days * sec_per_day;
+        } else {
+          td = -td;
         }
       }
-
-    } else {
-      td = td / per_sec;
-      if (td >= sec_per_day) {
-        out->days = td / sec_per_day;
-        td -= out->days * sec_per_day;
-      }
+    } else if (td >= sec_per_day) {
+      out->days = td / sec_per_day;
+      td -= out->days * sec_per_day;
     }
 
     if (td >= sec_per_hour) {

From b61b71c8e230ff56b1daa089189588ef70c0bcb4 Mon Sep 17 00:00:00 2001
From: Philipp Hoffmann <Philipp.Hoffmann@protonmail.com>
Date: Tue, 26 Mar 2024 00:47:31 +0100
Subject: [PATCH 19/22] reintroduce sfrac, minimize casting

---
 .../src/vendored/numpy/datetime/np_datetime.c | 58 +++++++++----------
 1 file changed, 27 insertions(+), 31 deletions(-)

diff --git a/pandas/_libs/src/vendored/numpy/datetime/np_datetime.c b/pandas/_libs/src/vendored/numpy/datetime/np_datetime.c
index 2a0cfc4c6bcaf..b43bbc47caf38 100644
--- a/pandas/_libs/src/vendored/numpy/datetime/np_datetime.c
+++ b/pandas/_libs/src/vendored/numpy/datetime/np_datetime.c
@@ -752,59 +752,55 @@ void pandas_timedelta_to_timedeltastruct(npy_timedelta td,
     }
 
     const npy_int64 per_day = sec_per_day * per_sec;
-    npy_int64 ifrac = td;
     const int sign = td < 0 ? -1 : 1;
+    const int is_negative = td < 0 ? 1 : 0;
     const int uneven_in_seconds = td % per_sec != 0 ? 1 : 0;
     // put frac in seconds
-    td = td / per_sec;
+    npy_int64 sfrac = td / per_sec - is_negative * uneven_in_seconds;
     if (sign < 0) {
-      td -= uneven_in_seconds;
       // even fraction
-      if ((-td % sec_per_day) != 0) {
-        // days = td / sec_per_day - is_even_fraction
-        out->days = td / sec_per_day - 1;
-        td -= sec_per_day * out->days;
+      if ((-sfrac % sec_per_day) != 0) {
+        out->days = sfrac / sec_per_day - 1;
+        sfrac -= sec_per_day * out->days;
       } else {
-        if (td <= sec_per_day) {
-          out->days = td / sec_per_day;
-          td = -td;
-          td += out->days * sec_per_day;
-        } else {
-          td = -td;
+        if (sfrac <= sec_per_day) {
+          out->days = sfrac / sec_per_day;
+          sfrac -= out->days * sec_per_day;
         }
+        sfrac = -sfrac;
       }
-    } else if (td >= sec_per_day) {
-      out->days = td / sec_per_day;
-      td -= out->days * sec_per_day;
+    } else if (sfrac >= sec_per_day) {
+      out->days = sfrac / sec_per_day;
+      sfrac -= out->days * sec_per_day;
     }
 
-    if (td >= sec_per_hour) {
-      out->hrs = (npy_int32)(td / sec_per_hour);
-      td %= sec_per_hour;
+    if (sfrac >= sec_per_hour) {
+      out->hrs = (npy_int32)(sfrac / sec_per_hour);
+      sfrac %= sec_per_hour;
     }
 
-    if (td >= sec_per_min) {
-      out->min = (npy_int32)(td / sec_per_min);
-      td %= sec_per_min;
+    if (sfrac >= sec_per_min) {
+      out->min = (npy_int32)(sfrac / sec_per_min);
+      sfrac %= sec_per_min;
     }
 
-    if (td >= 0) {
-      out->sec = (npy_int32)td;
+    if (sfrac >= 0) {
+      out->sec = (npy_int32)sfrac;
     }
 
     if (base > NPY_FR_s) {
-      ifrac = (ifrac - out->days * per_day) % per_sec;
+      npy_int32 ifrac = (npy_int32)((td - out->days * per_day) % per_sec);
 
       if (base == NPY_FR_ms) {
-        out->ms = (npy_int32)ifrac;
+        out->ms = ifrac;
       } else if (base == NPY_FR_us) {
-        out->ms = (npy_int32)(ifrac / 1000LL);
-        out->us = (npy_int32)(ifrac % 1000LL);
+        out->ms = ifrac / 1000LL;
+        out->us = ifrac % 1000LL;
       } else if (base == NPY_FR_ns) {
-        out->ms = (npy_int32)(ifrac / (1000LL * 1000LL));
+        out->ms = ifrac / (1000LL * 1000LL);
         ifrac = ifrac % (1000LL * 1000LL);
-        out->us = (npy_int32)(ifrac / 1000LL);
-        out->nanoseconds = (npy_int32)(ifrac % 1000LL);
+        out->us = ifrac / 1000LL;
+        out->nanoseconds = ifrac % 1000LL;
       }
       out->microseconds = out->ms * 1000 + out->us;
     }

From c3b19e0f445fe7d9d50a3972b4bdd9ef1b90d965 Mon Sep 17 00:00:00 2001
From: Philipp Hoffmann <Philipp.Hoffmann@protonmail.com>
Date: Tue, 26 Mar 2024 01:05:47 +0100
Subject: [PATCH 20/22] add comment

---
 pandas/_libs/src/vendored/numpy/datetime/np_datetime.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/pandas/_libs/src/vendored/numpy/datetime/np_datetime.c b/pandas/_libs/src/vendored/numpy/datetime/np_datetime.c
index b43bbc47caf38..fc04a4be17757 100644
--- a/pandas/_libs/src/vendored/numpy/datetime/np_datetime.c
+++ b/pandas/_libs/src/vendored/numpy/datetime/np_datetime.c
@@ -789,6 +789,7 @@ void pandas_timedelta_to_timedeltastruct(npy_timedelta td,
     }
 
     if (base > NPY_FR_s) {
+      // there will be at most 1 billion nanoseconds left here
       npy_int32 ifrac = (npy_int32)((td - out->days * per_day) % per_sec);
 
       if (base == NPY_FR_ms) {

From 80ce2834cd23bdb96994b7fd5452d13a48efa4f7 Mon Sep 17 00:00:00 2001
From: Philipp Hoffmann <Philipp.Hoffmann@protonmail.com>
Date: Tue, 26 Mar 2024 01:24:58 +0100
Subject: [PATCH 21/22] fix error

---
 pandas/_libs/src/vendored/numpy/datetime/np_datetime.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/pandas/_libs/src/vendored/numpy/datetime/np_datetime.c b/pandas/_libs/src/vendored/numpy/datetime/np_datetime.c
index fc04a4be17757..5e53be6f138f9 100644
--- a/pandas/_libs/src/vendored/numpy/datetime/np_datetime.c
+++ b/pandas/_libs/src/vendored/numpy/datetime/np_datetime.c
@@ -801,9 +801,8 @@ void pandas_timedelta_to_timedeltastruct(npy_timedelta td,
         out->ms = ifrac / (1000LL * 1000LL);
         ifrac = ifrac % (1000LL * 1000LL);
         out->us = ifrac / 1000LL;
-        out->nanoseconds = ifrac % 1000LL;
+        out->ns = ifrac % 1000LL;
       }
-      out->microseconds = out->ms * 1000 + out->us;
     }
 
   } break;
@@ -815,6 +814,8 @@ void pandas_timedelta_to_timedeltastruct(npy_timedelta td,
   }
   out->seconds =
       (npy_int32)(out->hrs * sec_per_hour + out->min * sec_per_min + out->sec);
+  out->microseconds = out->ms * 1000 + out->us;
+  out->nanoseconds = out->ns;
 }
 
 /*

From 322252e5b277f30c68018d276fb2e6ee375ffacb Mon Sep 17 00:00:00 2001
From: Philipp Hoffmann <Philipp.Hoffmann@protonmail.com>
Date: Tue, 26 Mar 2024 02:42:12 +0100
Subject: [PATCH 22/22] remove uneven_in_seconds

---
 pandas/_libs/src/vendored/numpy/datetime/np_datetime.c | 7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/pandas/_libs/src/vendored/numpy/datetime/np_datetime.c b/pandas/_libs/src/vendored/numpy/datetime/np_datetime.c
index 5e53be6f138f9..d60500a3c45dd 100644
--- a/pandas/_libs/src/vendored/numpy/datetime/np_datetime.c
+++ b/pandas/_libs/src/vendored/numpy/datetime/np_datetime.c
@@ -753,11 +753,12 @@ void pandas_timedelta_to_timedeltastruct(npy_timedelta td,
 
     const npy_int64 per_day = sec_per_day * per_sec;
     const int sign = td < 0 ? -1 : 1;
-    const int is_negative = td < 0 ? 1 : 0;
-    const int uneven_in_seconds = td % per_sec != 0 ? 1 : 0;
     // put frac in seconds
-    npy_int64 sfrac = td / per_sec - is_negative * uneven_in_seconds;
+    npy_int64 sfrac = td / per_sec;
     if (sign < 0) {
+      if (td % per_sec != 0)
+        sfrac -= 1;
+
       // even fraction
       if ((-sfrac % sec_per_day) != 0) {
         out->days = sfrac / sec_per_day - 1;