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Simplification of the dekkerMul2() subroutine.

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FossilOrigin-Name: bfe6432a46fd41bfadf4516a73b4e2523d9b453c3e4486fe6df7e1d25275dfb3
This commit is contained in:
drh 2023-07-05 14:42:50 +00:00
parent 6aa5a42beb
commit 1790ccb98b
3 changed files with 42 additions and 44 deletions
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12
manifest
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@ -1,5 +1,5 @@
C Add\sthe\sieee754_inc(r,N)\sfunction\sto\sthe\sieee754.c\sextension.
D 2023-07-05T12:00:32.550
C Simplification\sof\sthe\sdekkerMul2()\ssubroutine.
D 2023-07-05T14:42:50.334
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 5c6a3c7a88af0cbabb17707314b07f6026410610be73c6b6fba163b1cbf8b5ea
F src/util.c 04958d3937d7db7ae2d0ee18506c384596dfa909cc0c4a1347bf79081c107b5b
F src/vacuum.c 604fcdaebe76f3497c855afcbf91b8fa5046b32de3045bab89cc008d68e40104
F src/vdbe.c 74282a947234513872a83b0bab1b8c644ece64b3e27b053ef17677c8ff9c81e0
F src/vdbe.h 41485521f68e9437fdb7ec4a90f9d86ab294e9bb8281e33b235915e29122cfc0
@ -2043,8 +2043,8 @@ F vsixtest/vsixtest.tcl 6a9a6ab600c25a91a7acc6293828957a386a8a93
F vsixtest/vsixtest.vcxproj.data 2ed517e100c66dc455b492e1a33350c1b20fbcdc
F vsixtest/vsixtest.vcxproj.filters 37e51ffedcdb064aad6ff33b6148725226cd608e
F vsixtest/vsixtest_TemporaryKey.pfx e5b1b036facdb453873e7084e1cae9102ccc67a0
P fd987508d5589d42b46625c97cfb2feeac70fdb1cb11224610554b07a60644e6
R a945cf31e1bc8c6f26ee1341b6778e23
P 9a36f269451d8832f68e223ac3995493704364e7fd0cc772989c96e863a08d29
R aad77d965a4f588fb4cf332c1c0a5021
U drh
Z f1876ec8896b7ebc6d97122422450d0a
Z 45d04598133329d93f0fdb912f74ae6c
# Remove this line to create a well-formed Fossil manifest.

2
manifest.uuid
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@ -1 +1 @@
9a36f269451d8832f68e223ac3995493704364e7fd0cc772989c96e863a08d29
bfe6432a46fd41bfadf4516a73b4e2523d9b453c3e4486fe6df7e1d25275dfb3

72
src/util.c
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@ -386,23 +386,19 @@ u8 sqlite3StrIHash(const char *z){
return h;
}
/* Double-Double multiplication. *(z,zz) = (x,xx) * (y,yy)
/* Double-Double multiplication. (x[0],x[1]) *= (y,yy)
**
** Reference:
** T. J. Dekker, "A Floating-Point Technique for Extending the
** Available Precision". 1971-07-26.
*/
static void dekkerMul2(
double x, double xx,
double y, double yy,
double *z, double *zz
){
static void dekkerMul2(double *x, double y, double yy){
double hx, tx, hy, ty, p, q, c, cc;
u64 m;
memcpy(&m, &x, 8);
memcpy(&m, &x[0], 8);
m &= 0xfffffffffc000000L;
memcpy(&hx, &m, 8);
tx = x - hx;
tx = x[0] - hx;
memcpy(&m, &y, 8);
m &= 0xfffffffffc000000L;
memcpy(&hy, &m, 8);
@ -411,9 +407,9 @@ static void dekkerMul2(
q = hx*ty + tx*hy;
c = p+q;
cc = p - c + q + tx*ty;
cc = x*yy + xx*y + cc;
*z = c + cc;
*zz = c - *z + cc;
cc = x[0]*yy + x[1]*y + cc;
x[0] = c + cc;
x[1] = c - x[0] + cc;
}
/*
@ -587,39 +583,39 @@ do_atof_calc:
}
*pResult = r;
}else{
double r, rr;
double rr[2];
u64 s2;
r = (double)s;
s2 = (u64)r;
rr = s>=s2 ? (double)(s - s2) : -(double)(s2 - s);
rr[0] = (double)s;
s2 = (u64)rr[0];
rr[1] = s>=s2 ? (double)(s - s2) : -(double)(s2 - s);
if( e>0 ){
while( e>=100 ){
e -= 100;
dekkerMul2(r, rr, 1.0e+100, -1.5902891109759918046e+83, &r, &rr);
dekkerMul2(rr, 1.0e+100, -1.5902891109759918046e+83);
}
while( e>=10 ){
e -= 10;
dekkerMul2(r, rr, 1.0e+10, 0.0, &r, &rr);
dekkerMul2(rr, 1.0e+10, 0.0);
}
while( e>=1 ){
e -= 1;
dekkerMul2(r, rr, 1.0e+01, 0.0, &r, &rr);
dekkerMul2(rr, 1.0e+01, 0.0);
}
}else{
while( e<=-100 ){
e += 100;
dekkerMul2(r, rr, 1.0e-100, -1.99918998026028836196e-117, &r, &rr);
dekkerMul2(rr, 1.0e-100, -1.99918998026028836196e-117);
}
while( e<=-10 ){
e += 10;
dekkerMul2(r,rr, 1.0e-10, -3.6432197315497741579e-27, &r, &rr);
dekkerMul2(rr, 1.0e-10, -3.6432197315497741579e-27);
}
while( e<=-1 ){
e += 1;
dekkerMul2(r,rr, 1.0e-01, -5.5511151231257827021e-18, &r, &rr);
dekkerMul2(rr, 1.0e-01, -5.5511151231257827021e-18);
}
}
*pResult = r+rr;
*pResult = rr[0]+rr[1];
if( sqlite3IsNaN(*pResult) ) *pResult = 1e300*1e300;
}
if( sign<0 ) *pResult = -*pResult;
@ -982,35 +978,37 @@ void sqlite3FpDecode(FpDecode *p, double r, int iRound, int mxRound){
**
** SELECT decimal_sci(decimal_sub('1.0e+100',decimal(1.0e+100)));
*/
double rr = 0.0;
if( r>1.84e+19 ){
while( r>1.84e+119 ){
double rr[2];
rr[0] = r;
rr[1] = 0.0;
if( rr[0]>1.84e+19 ){
while( rr[0]>1.84e+119 ){
exp += 100;
dekkerMul2(r, rr, 1.0e-100, -1.99918998026028836196e-117, &r, &rr);
dekkerMul2(rr, 1.0e-100, -1.99918998026028836196e-117);
}
while( r>1.84e+29 ){
while( rr[0]>1.84e+29 ){
exp += 10;
dekkerMul2(r,rr, 1.0e-10, -3.6432197315497741579e-27, &r, &rr);
dekkerMul2(rr, 1.0e-10, -3.6432197315497741579e-27);
}
while( r>1.84e+19 ){
while( rr[0]>1.84e+19 ){
exp += 1;
dekkerMul2(r,rr, 1.0e-01, -5.5511151231257827021e-18, &r, &rr);
dekkerMul2(rr, 1.0e-01, -5.5511151231257827021e-18);
}
}else{
while( r<1.84e-82 ){
while( rr[0]<1.84e-82 ){
exp -= 100;
dekkerMul2(r, rr, 1.0e+100, -1.5902891109759918046e+83, &r, &rr);
dekkerMul2(rr, 1.0e+100, -1.5902891109759918046e+83);
}
while( r<1.84e+08 ){
while( rr[0]<1.84e+08 ){
exp -= 10;
dekkerMul2(r, rr, 1.0e+10, 0.0, &r, &rr);
dekkerMul2(rr, 1.0e+10, 0.0);
}
while( r<1.84e+18 ){
while( rr[0]<1.84e+18 ){
exp -= 1;
dekkerMul2(r, rr, 1.0e+01, 0.0, &r, &rr);
dekkerMul2(rr, 1.0e+01, 0.0);
}
}
v = rr<0.0 ? (u64)r-(u64)(-rr) : (u64)r+(u64)rr;
v = rr[1]<0.0 ? (u64)rr[0]-(u64)(-rr[1]) : (u64)rr[0]+(u64)rr[1];
}