Improved rounding of floating-point conversions in some corner cases.

FossilOrigin-Name: 436dccd42650a6ab0a74459ae42fdb3e36d853f934324acc2bc961f87c001852

diff --git a/manifest b/manifest
index 82b1ef8977b31bf156f9f5985781cadb3fc2961b..b48850df5e960a59b0a2830b377b2da2f135b637 100644 (file)
--- a/manifest
+++ b/manifest
@@ -1,5 +1,5 @@
-C In\sthe\sCLI,\sthe\s".quit"\scommand\sin\sa\s--cmd\sargument\scauses\san\simmediate\nexit.\s\s[forum:/forumpost/f057122b68|Forum\spost\sf057122b68].
-D 2026-02-19T17:20:40.116
+C Improved\srounding\sof\sfloating-point\sconversions\sin\ssome\scorner\scases.
+D 2026-02-20T12:27:52.339
 F .fossil-settings/binary-glob 61195414528fb3ea9693577e1980230d78a1f8b0a54c78cf1b9b24d0a409ed6a x
 F .fossil-settings/empty-dirs dbb81e8fc0401ac46a1491ab34a7f2c7c0452f2f06b54ebb845d024ca8283ef1
 F .fossil-settings/ignore-glob 35175cdfcf539b2318cb04a9901442804be81cd677d8b889fcc9149c21f239ea
@@ -803,7 +803,7 @@ F src/trigger.c a40440614bdf523090cc07223f4878f7e3c892bcd1a13afe18f90190daa5945d
 F src/update.c 3e5e7ff66fa19ebe4d1b113d480639a24cc1175adbefabbd1a948a07f28e37cf
 F src/upsert.c 215328c3f91623c520ec8672c44323553f12caeb4f01b1090ebdca99fdf7b4f1
 F src/utf.c 7267c3fb9e2467020507601af3354c2446c61f444387e094c779dccd5ca62165
-F src/util.c 72874125f70f61082bfb82b4580c1a320ab22b8cded2fb98e42ab98b39dc7bf1
+F src/util.c 43dce657e603820a31f196c703eb2213e10ef0c35b7960ac82312784294b6e4a
 F src/vacuum.c d3d35d8ae893d419ade5fa196d761a83bddcbb62137a1a157ae751ef38b26e82
 F src/vdbe.c 5328c99dd256ee8132383565a86e253543a85daccfd7477c52f20bac6b385a7f
 F src/vdbe.h 966d0677a540b7ea6549b7c4e1312fc0d830fce3a235a58c801f2cc31cf5ecf9
@@ -872,6 +872,7 @@ F test/analyzeF.test 40b5cc3ad7b10e81020d7ca86f1417647ecfae7477cfd88acc5aa7ae106
 F test/analyzeG.test 623be33038c49648872746c8dd8b23b5792c08fef173c55e82f1b12fca259852
 F test/analyzer1.test b6a624ec0af92eec209e1328465b66937c8fdf2fb442a3fa45321ddb3700f4aa
 F test/atof1.test bd21c4a0e718ab1470de07a2a79f2544d7903be34feebcc80de04beee4807b00
+F test/atof2.test 12912add57230495450e2fc94cb8ad1c9f3277f8843a3bc27079cae45c9782a1
 F test/atomic.test 065a453dde33c77ff586d91ccaa6ed419829d492dbb1a5694b8a09f3f9d7d061
 F test/atomic2.test b6863b4aa552543874f80b42fb3063f1c8c2e3d8e56b6562f00a3cc347b5c1da
 F test/atrc.c c388fac43dbba05c804432a7135ae688b32e8f25818e9994ffba4b64cf60c27c
@@ -2194,8 +2195,8 @@ F tool/warnings-clang.sh bbf6a1e685e534c92ec2bfba5b1745f34fb6f0bc2a362850723a9ee
 F tool/warnings.sh d924598cf2f55a4ecbc2aeb055c10bd5f48114793e7ba25f9585435da29e7e98
 F tool/win/sqlite.vsix deb315d026cc8400325c5863eef847784a219a2f
 F tool/winmain.c 00c8fb88e365c9017db14c73d3c78af62194d9644feaf60e220ab0f411f3604c
-P e540f6c370675ae043af8cdbb80f7eb17c08e50f7634e0b78f0b1dccf7bd4b18
-R e8a52a3904398a00cac725666cd6d19d
+P 4731cc8856aa4dcfad5db501648bfd0afef43d8c5f339e7b11a1e3ee64348b87
+R f79214badaf5b7fbc5067c602383d74f
 U drh
-Z ee96430e99114f754ef74526e72d7a91
+Z d75fc23742e879c6b1e0a5a3257032f9
 # Remove this line to create a well-formed Fossil manifest.

diff --git a/manifest.uuid b/manifest.uuid
index fd6ff32707c1a95811669d7560851cf46fd232d2..d8385da970816a08f18ad1afe15ceb26898d9f4b 100644 (file)
--- a/manifest.uuid
+++ b/manifest.uuid
@@ -1 +1 @@
-4731cc8856aa4dcfad5db501648bfd0afef43d8c5f339e7b11a1e3ee64348b87
+436dccd42650a6ab0a74459ae42fdb3e36d853f934324acc2bc961f87c001852

diff --git a/src/util.c b/src/util.c
index 048db497c2a0b641766e06da422e53453f6b662e..e2c54a35db39e44cfc5bf587b42db0b3023e4e23 100644 (file)
--- a/src/util.c
+++ b/src/util.c
@@ -649,11 +649,17 @@ static int countLeadingZeros(u64 m){
 static void sqlite3Fp2Convert10(u64 m, int e, int n, u64 *pD, int *pP){
   int p;
   u64 h;
+  assert( n>=1 && n<=18 );
   p = n - 1 - pwr2to10(e+63);
   h = sqlite3Multiply128(m, powerOfTen(p));
-  assert( -(e + pwr10to2(p) + 1) >=0 );
-  assert( -(e + pwr10to2(p) + 1) <64 );
-  *pD = h >> -(e + pwr10to2(p) + 1);
+  assert( -(e + pwr10to2(p) + 2) >= 0  );
+  assert( -(e + pwr10to2(p) + 1) <= 63 );
+  if( n==18 ){
+    h >>= -(e + pwr10to2(p) + 2);
+    *pD = (h + ((h<<1)&2))>>1;
+  }else{
+    *pD = h >> -(e + pwr10to2(p) + 1);
+  }
   *pP = -p;
 }
 

diff --git a/test/atof2.test b/test/atof2.test
new file mode 100644 (file)
index 0000000..5a68d13
--- /dev/null
+++ b/test/atof2.test
@@ -0,0 +1,35 @@
+# 2026-02-20
+#
+# The author disclaims copyright to this source code.  In place of
+# a legal notice, here is a blessing:
+#
+#    May you do good and not evil.
+#    May you find forgiveness for yourself and forgive others.
+#    May you share freely, never taking more than you give.
+#
+#***********************************************************************
+# 
+# Tests of the sqlite3AtoF() function.
+#
+
+set testdir [file dirname $argv0]
+source $testdir/tester.tcl
+
+# Rounding cases:
+#
+do_execsql_test atof2-1.0 {
+  SELECT format('%g',192.496475);
+} 192.496
+do_execsql_test atof2-1.1 {
+  SELECT format('%g',192.496501);
+} 192.497
+
+load_static_extension db ieee754
+do_execsql_test atof2-2.1 {
+  SELECT format('%!.30f',ieee754_inc(100.0,-1));
+} 99.9999999999999858
+do_execsql_test atof2-2.2 {
+  SELECT format('%!.30f',ieee754_inc(100.0,-2));
+} 99.9999999999999716
+
+finish_test