Add decimal rounding to the sqlite3FpDecode() routine.

FossilOrigin-Name: 27871140caa833f0bc0962e44356993938e93dcf81c1074382b1560a3e1aeb61

manifest

@@ -1,5 +1,5 @@
-C Experiments\swith\sa\snew\salgorithm\sfor\sconverting\sieee-754\sbinary64\snumbers\ninto\sdecimal.
-D 2023-06-30T18:35:43.344
+C Add\sdecimal\srounding\sto\sthe\ssqlite3FpDecode()\sroutine.
+D 2023-06-30T19:41:57.301
 F .fossil-settings/empty-dirs dbb81e8fc0401ac46a1491ab34a7f2c7c0452f2f06b54ebb845d024ca8283ef1
 F .fossil-settings/ignore-glob 35175cdfcf539b2318cb04a9901442804be81cd677d8b889fcc9149c21f239ea
 F LICENSE.md df5091916dbb40e6e9686186587125e1b2ff51f022cc334e886c19a0e9982724
@@ -590,7 +590,7 @@ F src/delete.c cd5f5cd06ed0b6a882ec1a8c2a0d73b3cecb28479ad19e9931c4706c5e2182be
 F src/expr.c 8d1656b65e26af3e34f78e947ac423f0d20c214ed25a67486e433bf16ca6b543
 F src/fault.c 460f3e55994363812d9d60844b2a6de88826e007
 F src/fkey.c a7fcbf7e66d14dbb73cf49f31489ebf66d0e6006c62b95246924a3bae9f37b36
-F src/func.c 699e19ca0dc580a024eb343f3a3abfb646e5438e36d377023d485a3038d789d5
+F src/func.c a6917bd4d4d81ac2320664ea982f85e1a08e566162ef1c776e965fc974b26502
 F src/global.c bd0892ade7289f6e20bff44c07d06371f2ff9b53cea359e7854b9b72f65adc30
 F src/hash.c 9ee4269fb1d6632a6fecfb9479c93a1f29271bddbbaf215dd60420bcb80c7220
 F src/hash.h 3340ab6e1d13e725571d7cee6d3e3135f0779a7d8e76a9ce0a85971fa3953c51
@@ -642,7 +642,7 @@ F src/shell.c.in 2c02c819349de410d63fcc0217763dfe5a42dbe58f2d68046d4ea8a376d12c2
 F src/sqlite.h.in 3076d78836b6dac53b3ab0875fc8fd15bca8077aad4d33c85336e05af6aef8c7
 F src/sqlite3.rc 5121c9e10c3964d5755191c80dd1180c122fc3a8
 F src/sqlite3ext.h da473ce2b3d0ae407a6300c4a164589b9a6bfdbec9462688a8593ff16f3bb6e4
-F src/sqliteInt.h 6ef127217c54e4707b1ca500508340542ca3c2a5aa08ee7a00aaa4834e68992d
+F src/sqliteInt.h 333195d3a62c34af256216e229deb052d87d1068785467a590b56acba0b6c711
 F src/sqliteLimit.h 33b1c9baba578d34efe7dfdb43193b366111cdf41476b1e82699e14c11ee1fb6
 F src/status.c 160c445d7d28c984a0eae38c144f6419311ed3eace59b44ac6dafc20db4af749
 F src/table.c 0f141b58a16de7e2fbe81c308379e7279f4c6b50eb08efeec5892794a0ba30d1
@@ -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 447fd1d981bab37788397c24f980ce555438168f28badde1227441f6d67f1214
+F src/util.c 4a7343a01de122783d6d84c508af15674990578703d5bf55294066978c943f35
 F src/vacuum.c 604fcdaebe76f3497c855afcbf91b8fa5046b32de3045bab89cc008d68e40104
 F src/vdbe.c 74282a947234513872a83b0bab1b8c644ece64b3e27b053ef17677c8ff9c81e0
 F src/vdbe.h 41485521f68e9437fdb7ec4a90f9d86ab294e9bb8281e33b235915e29122cfc0
@@ -2041,11 +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 7afad1f759f7ceda873c6d869422fd56fe4399c2d24d47ad9bc3b84b06d830d1
-R b84c58ae5f50c9a21c1125fd73d7f10d
-T *branch * fp-to-decimal-refactor
-T *sym-fp-to-decimal-refactor *
-T -sym-trunk *
+P e923405e448385085224f9289991b303d86b02763535ea77d6fcee98ba6fc1f2
+R 49ab12ffcc52cccbb997811489070376
 U drh
-Z aad0befdc05a87e7f362b0543d2a6962
+Z 1293fc1c53a0c963d9c920ddba4be394
 # Remove this line to create a well-formed Fossil manifest.

manifest.uuid

@@ -1 +1 @@
-e923405e448385085224f9289991b303d86b02763535ea77d6fcee98ba6fc1f2
+27871140caa833f0bc0962e44356993938e93dcf81c1074382b1560a3e1aeb61

src/func.c

@@ -2379,10 +2379,12 @@ static void fpdecodeFunc(
   sqlite3_value **argv
 ){
   double r = sqlite3_value_double(argv[0]);
+  int n = 15;
   FpDecode s;
   char zBuf[50];
-  UNUSED_PARAMETER(argc);
-  sqlite3FpDecode(&s, r);
+
+  if( argc>=2 ) n = sqlite3_value_int(argv[1]);
+  sqlite3FpDecode(&s, r, n);
   sqlite3_snprintf(sizeof(zBuf), zBuf, "%c%.*s/%d", s.sign, s.n, s.z, s.iDP);
   sqlite3_result_text(context, zBuf, -1, SQLITE_TRANSIENT);
 }
@@ -2462,6 +2464,7 @@ void sqlite3RegisterBuiltinFunctions(void){
 
 #if 1  /* Temporary prototyping function */
     FUNCTION(fpdecode,           1, 0, 0, fpdecodeFunc     ),
+    FUNCTION(fpdecode,           2, 0, 0, fpdecodeFunc     ),
 #endif
   
 #ifndef SQLITE_OMIT_FLOATING_POINT

src/sqliteInt.h

@@ -4611,7 +4611,7 @@ struct FpDecode {
   char z[24];          /* Significiant digits */
 };
 
-void sqlite3FpDecode(FpDecode*,double);
+void sqlite3FpDecode(FpDecode*,double,int);
 char *sqlite3MPrintf(sqlite3*,const char*, ...);
 char *sqlite3VMPrintf(sqlite3*,const char*, va_list);
 #if defined(SQLITE_DEBUG) || defined(SQLITE_HAVE_OS_TRACE)

src/util.c

@@ -931,8 +931,13 @@ 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.
 */
-void sqlite3FpDecode(FpDecode *p, double r){
+void sqlite3FpDecode(FpDecode *p, double r, int iRound){
   int i;
   u64 v;
   int e, exp = 0;
@@ -983,10 +988,31 @@ void sqlite3FpDecode(FpDecode *p, double r){
     while( r<1.0e+17   ){ exp--;    r *= 10.0;     }
   }
   v = (u64)r;
-  i = sizeof(p->z);
+  i = sizeof(p->z)-1;
   while( v ){  p->z[i--] = (v%10) + '0'; v /= 10; }
-  p->n = sizeof(p->z) - i;
+  p->n = sizeof(p->z) - 1 - i;
   p->iDP = p->n + exp;
+  if( iRound<0 ) iRound = p->iDP - iRound;
+  if( iRound>0 && iRound<p->n ){
+    char *z = &p->z[i+1];
+    p->n = iRound;
+    if( z[iRound]>='5' ){
+      int j = iRound-1;
+      while( 1 /*exit-by-break*/ ){
+        z[j]++;
+        if( z[j]<='9' ) break;
+        z[j] = '0';
+        if( j==0 ){
+          p->z[i--] = '1';
+          p->n++;
+          p->iDP++;
+          break;
+        }else{
+          j--;
+        }
+      }
+    }
+  }
   memmove(p->z, &p->z[i+1], p->n);
   while( p->n>0 && p->z[p->n-1]=='0' ){ p->n--; }
 }