From 5270d7424d2e9f47c450fe85753c0768e2f41b3b Mon Sep 17 00:00:00 2001
From: drh <>
Date: Mon, 3 Jul 2023 10:18:02 +0000
Subject: [PATCH] Faster Dekker multiplication that removes the restriction on
 input magnitude.

FossilOrigin-Name: 2994caf5884be07c889519c78fbac4ddcf267fcfe6a3265ecb6390bcd574532e
---
 manifest      | 12 ++++++------
 manifest.uuid |  2 +-
 src/util.c    | 18 +++++++++---------
 3 files changed, 16 insertions(+), 16 deletions(-)

diff --git a/manifest b/manifest
index 5ae086cfa2..593e1f7fd9 100644
--- a/manifest
+++ b/manifest
@@ -1,5 +1,5 @@
-C Fix\sone\sconstant\sin\sthe\snormalization\slogic.\s\sImproved\serror\soutput\nfrom\satof1.test.
-D 2023-07-03T10:00:38.019
+C Faster\sDekker\smultiplication\sthat\sremoves\sthe\srestriction\son\sinput\smagnitude.
+D 2023-07-03T10:18:02.499
 F .fossil-settings/empty-dirs dbb81e8fc0401ac46a1491ab34a7f2c7c0452f2f06b54ebb845d024ca8283ef1
 F .fossil-settings/ignore-glob 35175cdfcf539b2318cb04a9901442804be81cd677d8b889fcc9149c21f239ea
 F LICENSE.md df5091916dbb40e6e9686186587125e1b2ff51f022cc334e886c19a0e9982724
@@ -705,7 +705,7 @@ F src/trigger.c ad6ab9452715fa9a8075442e15196022275b414b9141b566af8cdb7a1605f2b0
 F src/update.c 0aa36561167a7c40d01163238c297297962f31a15a8d742216b3c37cdf25f731
 F src/upsert.c 5303dc6c518fa7d4b280ec65170f465c7a70b7ac2b22491598f6d0b4875b3145
 F src/utf.c ee39565f0843775cc2c81135751ddd93eceb91a673ea2c57f61c76f288b041a0
-F src/util.c eae1eeaf2de968bc32d81274b6209a6685d8f68f8a44fb80bc77602860feede8
+F src/util.c e920f80d429285da398e33852e47b1731fd474d4fc8fd38ea16e74f7f15c100c
 F src/vacuum.c 604fcdaebe76f3497c855afcbf91b8fa5046b32de3045bab89cc008d68e40104
 F src/vdbe.c 74282a947234513872a83b0bab1b8c644ece64b3e27b053ef17677c8ff9c81e0
 F src/vdbe.h 41485521f68e9437fdb7ec4a90f9d86ab294e9bb8281e33b235915e29122cfc0
@@ -2041,8 +2041,8 @@ F vsixtest/vsixtest.tcl 6a9a6ab600c25a91a7acc6293828957a386a8a93
 F vsixtest/vsixtest.vcxproj.data 2ed517e100c66dc455b492e1a33350c1b20fbcdc
 F vsixtest/vsixtest.vcxproj.filters 37e51ffedcdb064aad6ff33b6148725226cd608e
 F vsixtest/vsixtest_TemporaryKey.pfx e5b1b036facdb453873e7084e1cae9102ccc67a0
-P 4fa6938dac2d3d813a37664053db31451a2a065f78dd212488f5f7f8d583ddc5
-R df6eb47114802d2c438e907f9bdbb126
+P d3c48807100a358a70fdd799c8935eba1b765ace2e1ddea4475fd673006cb6da
+R 46c57ca0802519e59042da4b712e623e
 U drh
-Z 7f5799444e9a2cb0ee3bb904fd4adcc7
+Z 937d038b18f0b1ea37450ce437120a68
 # Remove this line to create a well-formed Fossil manifest.
diff --git a/manifest.uuid b/manifest.uuid
index a69b8691ba..1fa06bc7fa 100644
--- a/manifest.uuid
+++ b/manifest.uuid
@@ -1 +1 @@
-d3c48807100a358a70fdd799c8935eba1b765ace2e1ddea4475fd673006cb6da
\ No newline at end of file
+2994caf5884be07c889519c78fbac4ddcf267fcfe6a3265ecb6390bcd574532e
\ No newline at end of file
diff --git a/src/util.c b/src/util.c
index 40662f021c..7456599bc9 100644
--- a/src/util.c
+++ b/src/util.c
@@ -940,10 +940,15 @@ static void mul2(
   double *z, double *zz
 ){
   double hx, tx, hy, ty, p, q, c, cc;
-  p = 67108865.0 * x;
-  hx = x - p + p; tx = x - hx;
-  p = 67108865.0 * y;
-  hy = y - p + p; ty = y - hy;
+  u64 m;
+  memcpy(&m, &x, 8);
+  m &= 0xfffffffffc000000L;
+  memcpy(&hx, &m, 8);
+  tx = x - hx;
+  memcpy(&m, &y, 8);
+  m &= 0xfffffffffc000000L;
+  memcpy(&hy, &m, 8);
+  ty = y - hy;
   p = hx*hy;
   q = hx*ty + tx*hy;
   c = p+q;
@@ -1010,11 +1015,6 @@ void sqlite3FpDecode(FpDecode *p, double r, int iRound, int mxRound){
     double rr = 0.0;
     if( r>=1.0e+19 ){
       while( r>=1.0e+119 ){
-        if( r>=1.0e+300 ){
-          exp += 300;
-          r *= 1.0e-300;
-          break;
-        }
         exp += 100;
         mul2(r, rr, 1.0e-100, -1.99918998026028836196e-117, &r, &rr);
       }
-- 
2.47.2