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Faster and smaller implementation of sqlite3AtoF() based on a suggestion

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from Cezary H. Noweta.

FossilOrigin-Name: fd2e0e7a770c2ce9355068aad1024c3d2861c104fd3be304a91c55ca742155fa
This commit is contained in:
drh
2017-12-26 14:46:20 +00:00
parent c8f44d245c
commit 02a43f6def
3 changed files with 28 additions and 15 deletions
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15
manifest
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@@ -1,5 +1,5 @@
C Fix\scrashes\sthat\scould\soccur\sif\sSQL\sNULL\svalues\swere\spassed\sto\sthe\sbuilt-in\nFTS5\ssnippet\sfunction.\sEdit:\sbreaks\samalgamation\sbuilds. C Faster\sand\ssmaller\simplementation\sof\ssqlite3AtoF()\sbased\son\sa\ssuggestion\nfrom\sCezary\sH.\sNoweta.
D 2017-12-26T14:32:25.807 D 2017-12-26T14:46:20.800
F Makefile.in ceb40bfcb30ebba8e1202b34c56ff7e13e112f9809e2381d99be32c2726058f5 F Makefile.in ceb40bfcb30ebba8e1202b34c56ff7e13e112f9809e2381d99be32c2726058f5
F Makefile.linux-gcc 7bc79876b875010e8c8f9502eb935ca92aa3c434 F Makefile.linux-gcc 7bc79876b875010e8c8f9502eb935ca92aa3c434
F Makefile.msc 6480671f7c129e61208d69492b3c71ce4310d49fceac83cfb17f1c081e242b69 F Makefile.msc 6480671f7c129e61208d69492b3c71ce4310d49fceac83cfb17f1c081e242b69
@@ -545,7 +545,7 @@ F src/treeview.c eae35972ff44f67064de2eaf35f04afe94e7aea3271a8b3bcebb3f954880fec
F src/trigger.c 775053eecf6b73062e243404b56f5064446254d5cce17d8704d5cdffd72a546a F src/trigger.c 775053eecf6b73062e243404b56f5064446254d5cce17d8704d5cdffd72a546a
F src/update.c 961bd1265d4d1e5cd65c9a54fa5122fb7aefcb003fcf2de0c092fceb7e58972c F src/update.c 961bd1265d4d1e5cd65c9a54fa5122fb7aefcb003fcf2de0c092fceb7e58972c
F src/utf.c 810fbfebe12359f10bc2a011520a6e10879ab2a163bcb26c74768eab82ea62a5 F src/utf.c 810fbfebe12359f10bc2a011520a6e10879ab2a163bcb26c74768eab82ea62a5
F src/util.c d01fa6f45bfad3b65fb2490513aa2e0676412c61b4b094340b513cf72c3704a4 F src/util.c 7315e97a8dc2c8e19ca64196c652cf0a65d13fd0a211b2cec082062372dc6261
F src/vacuum.c 90839322fd5f00df9617eb21b68beda9b6e2a2937576b0d65985e4aeb1c53739 F src/vacuum.c 90839322fd5f00df9617eb21b68beda9b6e2a2937576b0d65985e4aeb1c53739
F src/vdbe.c 3393b508d9ad084ffce232a7c53e375ef5ac99b50b685c5131fcdfce97a9d534 F src/vdbe.c 3393b508d9ad084ffce232a7c53e375ef5ac99b50b685c5131fcdfce97a9d534
F src/vdbe.h d50cadf12bcf9fb99117ef392ce1ea283aa429270481426b6e8b0280c101fd97 F src/vdbe.h d50cadf12bcf9fb99117ef392ce1ea283aa429270481426b6e8b0280c101fd97
@@ -1687,8 +1687,7 @@ F vsixtest/vsixtest.tcl 6a9a6ab600c25a91a7acc6293828957a386a8a93
F vsixtest/vsixtest.vcxproj.data 2ed517e100c66dc455b492e1a33350c1b20fbcdc F vsixtest/vsixtest.vcxproj.data 2ed517e100c66dc455b492e1a33350c1b20fbcdc
F vsixtest/vsixtest.vcxproj.filters 37e51ffedcdb064aad6ff33b6148725226cd608e F vsixtest/vsixtest.vcxproj.filters 37e51ffedcdb064aad6ff33b6148725226cd608e
F vsixtest/vsixtest_TemporaryKey.pfx e5b1b036facdb453873e7084e1cae9102ccc67a0 F vsixtest/vsixtest_TemporaryKey.pfx e5b1b036facdb453873e7084e1cae9102ccc67a0
P ebfea8728fec955b1d74b1d0a3de498fd1a32e8b39572a8fdab606ed87b169b4 P 6a790b67a0a5c698526db16ea262b13ecdd1b6ca74e80bdccfcad88ddbdc933a
Q +553a3ad32498ddda920216cd44a376a439a58fbb326d2d3800528867db1ffa9d R c3240df89b3aa2504611bdd745085460
R 742f62796704fae3ae9dc15618c72290 U drh
U dan Z 3dc20c6e2c72c6078d443025934f152b
Z ecb93df9cf8c6f4bd1c8f7a6ca97d753

2
manifest.uuid
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@@ -1 +1 @@
6a790b67a0a5c698526db16ea262b13ecdd1b6ca74e80bdccfcad88ddbdc933a fd2e0e7a770c2ce9355068aad1024c3d2861c104fd3be304a91c55ca742155fa

26
src/util.c
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@@ -320,6 +320,24 @@ int sqlite3_strnicmp(const char *zLeft, const char *zRight, int N){
return N<0 ? 0 : UpperToLower[*a] - UpperToLower[*b]; return N<0 ? 0 : UpperToLower[*a] - UpperToLower[*b];
} }
/*
** Compute 10 to the E-th power. Examples: E==1 results in 10.
** E==2 results in 100. E==50 results in 1.0e50.
**
** This routine only works for values of E between 1 and 341.
*/
static LONGDOUBLE_TYPE sqlite3Pow10(int E){
LONGDOUBLE_TYPE x = 10.0;
LONGDOUBLE_TYPE r = 1.0;
while(1){
if( E & 1 ) r *= x;
E >>= 1;
if( E==0 ) break;
x *= x;
}
return r;
}
/* /*
** The string z[] is an text representation of a real number. ** The string z[] is an text representation of a real number.
** Convert this string to a double and write it into *pResult. ** Convert this string to a double and write it into *pResult.
@@ -475,11 +493,10 @@ do_atof_calc:
if( e==0 ){ /*OPTIMIZATION-IF-TRUE*/ if( e==0 ){ /*OPTIMIZATION-IF-TRUE*/
result = (double)s; result = (double)s;
}else{ }else{
LONGDOUBLE_TYPE scale = 1.0;
/* attempt to handle extremely small/large numbers better */ /* attempt to handle extremely small/large numbers better */
if( e>307 ){ /*OPTIMIZATION-IF-TRUE*/ if( e>307 ){ /*OPTIMIZATION-IF-TRUE*/
if( e<342 ){ /*OPTIMIZATION-IF-TRUE*/ if( e<342 ){ /*OPTIMIZATION-IF-TRUE*/
while( e%308 ) { scale *= 1.0e+1; e -= 1; } LONGDOUBLE_TYPE scale = sqlite3Pow10(e-308);
if( esign<0 ){ if( esign<0 ){
result = s / scale; result = s / scale;
result /= 1.0e+308; result /= 1.0e+308;
@@ -499,10 +516,7 @@ do_atof_calc:
} }
} }
}else{ }else{
/* 1.0e+22 is the largest power of 10 than can be LONGDOUBLE_TYPE scale = sqlite3Pow10(e);
** represented exactly. */
while( e%22 ) { scale *= 1.0e+1; e -= 1; }
while( e>0 ) { scale *= 1.0e+22; e -= 22; }
if( esign<0 ){ if( esign<0 ){
result = s / scale; result = s / scale;
}else{ }else{