Improved header comment on the sqlite3FpDecode() implementation.

For the fpdecode() SQL function (available in debug builds only) limit
the value of the third parameter (mxRound) to be positive.

FossilOrigin-Name: 56af06fa12104a1fe119d7087746011183af053834eac72d0fb69f60d98054c6

manifest

@@ -1,5 +1,5 @@
-C Disable\sthe\somit-noop-join\soptimization\swhen\sthere\sare\s64\sor\smore\sterms\sin\nthe\sORDER\sBY\sclause.
-D 2024-06-09T17:34:03.640
+C Improved\sheader\scomment\son\sthe\ssqlite3FpDecode()\simplementation.\nFor\sthe\sfpdecode()\sSQL\sfunction\s(available\sin\sdebug\sbuilds\sonly)\slimit\nthe\svalue\sof\sthe\sthird\sparameter\s(mxRound)\sto\sbe\spositive.
+D 2024-06-10T12:43:03.794
 F .fossil-settings/empty-dirs dbb81e8fc0401ac46a1491ab34a7f2c7c0452f2f06b54ebb845d024ca8283ef1
 F .fossil-settings/ignore-glob 35175cdfcf539b2318cb04a9901442804be81cd677d8b889fcc9149c21f239ea
 F LICENSE.md df5091916dbb40e6e9686186587125e1b2ff51f022cc334e886c19a0e9982724
@@ -708,7 +708,7 @@ F src/delete.c cb766727c78e715f9fb7ec8a7d03658ed2a3016343ca687acfcec9083cdca500
 F src/expr.c af9c9242be0df17280faf36c9810339de9df3d7a64ac8d33a5190a1400086ee5
 F src/fault.c 460f3e55994363812d9d60844b2a6de88826e007
 F src/fkey.c 852f93c0ef995e0c2b8983059a2b97151c194cc8259e21f5bc2b7ac508348c2a
-F src/func.c f1f57c6863c1380f31ecf3d61732495bfff847a8e35a832c7e306e310db5a799
+F src/func.c 1f61e32e7a357e615b5d2e774bee563761fce4f2fd97ecb0f72c33e62a2ada5f
 F src/global.c 61a419dd9e993b9be0f91de4c4ccf322b053eb829868e089f0321dd669be3b90
 F src/hash.c 9ee4269fb1d6632a6fecfb9479c93a1f29271bddbbaf215dd60420bcb80c7220
 F src/hash.h 3340ab6e1d13e725571d7cee6d3e3135f0779a7d8e76a9ce0a85971fa3953c51
@@ -823,7 +823,7 @@ F src/trigger.c 0858f75818ed1580332db274f1032bcc5effe567cb132df5c5be8b1d800ca97f
 F src/update.c 732404a04d1737ef14bb6ec6b84f74edf28b3c102a92ae46b4855438a710efe7
 F src/upsert.c 2e60567a0e9e8520c18671b30712a88dc73534474304af94f32bb5f3ef65ac65
 F src/utf.c f23165685a67b4caf8ec08fb274cb3f319103decfb2a980b7cfd55d18dfa855e
-F src/util.c 4d6d7ebfe6772a1b950c97bbb1d1a72ad4874617ec498ab8aa73b7f5a43e44bb
+F src/util.c 5d1a0134cf4240648d1c6bb5cc8efaca0ea2b5d5c840985aec7e947271f04375
 F src/vacuum.c 604fcdaebe76f3497c855afcbf91b8fa5046b32de3045bab89cc008d68e40104
 F src/vdbe.c b05777c3ff2ed7b9dfc347e7cdee18e371aa6811cef1fe83454691b0dbe2cc9f
 F src/vdbe.h c2d78d15112c3fc5ab87f5e8e0b75d2db1c624409de2e858c3d1aafb1650bb4f
@@ -2195,8 +2195,8 @@ F vsixtest/vsixtest.tcl 6a9a6ab600c25a91a7acc6293828957a386a8a93
 F vsixtest/vsixtest.vcxproj.data 2ed517e100c66dc455b492e1a33350c1b20fbcdc
 F vsixtest/vsixtest.vcxproj.filters 37e51ffedcdb064aad6ff33b6148725226cd608e
 F vsixtest/vsixtest_TemporaryKey.pfx e5b1b036facdb453873e7084e1cae9102ccc67a0
-P c4a9dda2809c6e0e3d928e11e5553ead82cd9df551bcd35b11a7d869ef80ab8e
-R 3c43b2ce12f159be8c966958fcb4055b
+P 40de3939792e17df25598b3e60d1cebcecde2b00832acd55604f14b21398a9a7
+R 3798b5dfb33f66d6cffbf2ab99073009
 U drh
-Z a3915588a6885a87c7d5fcd05fe5cf89
+Z 6cba9a77bc527574a7f08d08f1d8739d
 # Remove this line to create a well-formed Fossil manifest.

manifest.uuid

@@ -1 +1 @@
-40de3939792e17df25598b3e60d1cebcecde2b00832acd55604f14b21398a9a7
+56af06fa12104a1fe119d7087746011183af053834eac72d0fb69f60d98054c6

src/func.c

@@ -2547,6 +2547,7 @@ static void fpdecodeFunc(
   x = sqlite3_value_double(argv[0]);
   y = sqlite3_value_int(argv[1]);
   z = sqlite3_value_int(argv[2]);
+  if( z<=0 ) z = 1;
   sqlite3FpDecode(&s, x, y, z);
   if( s.isSpecial==2 ){
     sqlite3_snprintf(sizeof(zBuf), zBuf, "NaN");

src/util.c

@@ -1015,10 +1015,13 @@ int sqlite3Atoi(const char *z){
 ** Decode a floating-point value into an approximate decimal
 ** representation.
 **
-** Round the decimal representation to n significant digits if
-** n is positive.  Or round to -n signficant digits after the
-** decimal point if n is negative.  No rounding is performed if
-** n is zero.
+** If iRound<=0 then round to -iRound significant digits to the
+** the left of the decimal point, or to a maximum of mxRound total
+** significant digits.
+**
+** If iRound>0 round to min(iRound,mxRound) significant digits total.
+**
+** mxRound must be positive.
 **
 ** The significant digits of the decimal representation are
 ** stored in p->z[] which is a often (but not always) a pointer
@@ -1032,6 +1035,8 @@ void sqlite3FpDecode(FpDecode *p, double r, int iRound, int mxRound){
   p->isSpecial = 0;
   p->z = p->zBuf;
 
+  assert( mxRound>0 );
+
   /* Convert negative numbers to positive.  Deal with Infinity, 0.0, and
   ** NaN. */
   if( r<0.0 ){