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Overview
| Comment: | Test versions of getVarint functions. The updates essentially utilize loop unrolling and some shifting/anding tricks to minimize the number of logical operations required. (CVS 5072) |
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| Downloads: | Tarball | ZIP archive |
| Timelines: | family | ancestors | descendants | both | trunk |
| Files: | files | file ages | folders |
| SHA1: |
682dc24dbe82d0326377e27c5ff97db3 |
| User & Date: | shane 2008-05-01 02:47:04.000 |
Context
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2008-05-01
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| 17:03 | Fix harmless compiler warnings. (CVS 5073) (check-in: 227a6f67c2 user: drh tags: trunk) | |
| 02:47 | Test versions of getVarint functions. The updates essentially utilize loop unrolling and some shifting/anding tricks to minimize the number of logical operations required. (CVS 5072) (check-in: 682dc24dbe user: shane tags: trunk) | |
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2008-04-30
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| 16:38 | Add comment to speculate when setting journal_mode=OFF on VACUUM does not help performance. No changes to code. (CVS 5071) (check-in: 9c8b4babb2 user: drh tags: trunk) | |
Changes
Changes to src/util.c.
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10 11 12 13 14 15 16 | ** ************************************************************************* ** Utility functions used throughout sqlite. ** ** This file contains functions for allocating memory, comparing ** strings, and stuff like that. ** | | | 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 | ** ************************************************************************* ** Utility functions used throughout sqlite. ** ** This file contains functions for allocating memory, comparing ** strings, and stuff like that. ** ** $Id: util.c,v 1.225 2008/05/01 02:47:04 shane Exp $ */ #include "sqliteInt.h" #include <stdarg.h> #include <ctype.h> /* |
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529 530 531 532 533 534 535 |
}
/*
** Read a 64-bit variable-length integer from memory starting at p[0].
** Return the number of bytes read. The value is stored in *v.
*/
int sqlite3GetVarint(const unsigned char *p, u64 *v){
| | | | | | > | > > > > > > | | > | | > > > > | > > > > > | | > > > > > > | > > > > > > | | > > > > > > | > | > > > > > > > > > > > > > > > | > > > > | > > > > > > > > > > > > > > > | > > > > > > > > > > > > > > | > > > > > > > > > > > > > > > > | | > > > > | > > > | > > > > > > > > > > | | | > | < > > | > > > > > > | > > > > | > > > > > > > > > | | | > > > > > > > > | > > > | > > > > > > > > > > > > | > > > > > > > > > > > > | > > > > > > > > > | | > > > > > > > > > > > > > > > > > > > > > > > > > | 529 530 531 532 533 534 535 536 537 538 539 540 541 542 543 544 545 546 547 548 549 550 551 552 553 554 555 556 557 558 559 560 561 562 563 564 565 566 567 568 569 570 571 572 573 574 575 576 577 578 579 580 581 582 583 584 585 586 587 588 589 590 591 592 593 594 595 596 597 598 599 600 601 602 603 604 605 606 607 608 609 610 611 612 613 614 615 616 617 618 619 620 621 622 623 624 625 626 627 628 629 630 631 632 633 634 635 636 637 638 639 640 641 642 643 644 645 646 647 648 649 650 651 652 653 654 655 656 657 658 659 660 661 662 663 664 665 666 667 668 669 670 671 672 673 674 675 676 677 678 679 680 681 682 683 684 685 686 687 688 689 690 691 692 693 694 695 696 697 698 699 700 701 702 703 704 705 706 707 708 709 710 711 712 713 714 715 716 717 718 719 720 721 722 723 724 725 726 727 728 729 730 731 732 733 734 735 736 737 738 739 740 741 742 743 744 745 746 747 748 749 750 751 752 753 754 755 756 757 758 759 760 761 762 763 764 765 766 767 768 769 770 771 772 773 774 775 776 777 778 779 780 781 782 783 784 785 786 787 788 789 790 791 792 793 794 795 796 797 798 799 800 801 802 803 804 805 806 807 808 809 810 811 812 813 814 815 |
}
/*
** Read a 64-bit variable-length integer from memory starting at p[0].
** Return the number of bytes read. The value is stored in *v.
*/
int sqlite3GetVarint(const unsigned char *p, u64 *v){
u32 a,b,s;
a = *p;
// a: p0 (unmasked)
if (!(a&0x80))
{
*v = a;
return 1;
}
p++;
b = *p;
// b: p1 (unmasked)
if (!(b&0x80))
{
a &= 0x7f;
a = a<<7;
a |= b;
*v = a;
return 2;
}
p++;
a = a<<14;
a |= *p;
// a: p0<<14 | p2 (unmasked)
if (!(a&0x80))
{
a &= (0x7f<<14)|(0x7f);
b &= 0x7f;
b = b<<7;
a |= b;
*v = a;
return 3;
}
// CSE1 from below
a &= (0x7f<<14)|(0x7f);
p++;
b = b<<14;
b |= *p;
// b: p1<<14 | p3 (unmasked)
if (!(b&0x80))
{
b &= (0x7f<<14)|(0x7f);
// moved CSE1 up
// a &= (0x7f<<14)|(0x7f);
a = a<<7;
a |= b;
*v = a;
return 4;
}
// a: p0<<14 | p2 (masked)
// b: p1<<14 | p3 (unmasked)
// 1:save off p0<<21 | p1<<14 | p2<<7 | p3 (masked)
// moved CSE1 up
// a &= (0x7f<<14)|(0x7f);
b &= (0x7f<<14)|(0x7f);
s = a;
// s: p0<<14 | p2 (masked)
p++;
a = a<<14;
a |= *p;
// a: p0<<28 | p2<<14 | p4 (unmasked)
if (!(a&0x80))
{
// we can skip these cause they were (effectively) done above in calc'ing s
// a &= (0x7f<<28)|(0x7f<<14)|(0x7f);
// b &= (0x7f<<14)|(0x7f);
b = b<<7;
a |= b;
s = s>>18;
*v = ((u64)s)<<32 | a;
return 5;
}
// 2:save off p0<<21 | p1<<14 | p2<<7 | p3 (masked)
s = s<<7;
s |= b;
// s: p0<<21 | p1<<14 | p2<<7 | p3 (masked)
p++;
b = b<<14;
b |= *p;
// b: p1<<28 | p3<<14 | p5 (unmasked)
if (!(b&0x80))
{
// we can skip this cause it was (effectively) done above in calc'ing s
// b &= (0x7f<<28)|(0x7f<<14)|(0x7f);
a &= (0x7f<<14)|(0x7f);
a = a<<7;
a |= b;
s = s>>18;
*v = ((u64)s)<<32 | a;
return 6;
}
p++;
a = a<<14;
a |= *p;
// a: p2<<28 | p4<<14 | p6 (unmasked)
if (!(a&0x80))
{
a &= (0x7f<<28)|(0x7f<<14)|(0x7f);
b &= (0x7f<<14)|(0x7f);
b = b<<7;
a |= b;
s = s>>11;
*v = ((u64)s)<<32 | a;
return 7;
}
// CSE2 from below
a &= (0x7f<<14)|(0x7f);
p++;
b = b<<14;
b |= *p;
// b: p3<<28 | p5<<14 | p7 (unmasked)
if (!(b&0x80))
{
b &= (0x7f<<28)|(0x7f<<14)|(0x7f);
// moved CSE2 up
// a &= (0x7f<<14)|(0x7f);
a = a<<7;
a |= b;
s = s>>4;
*v = ((u64)s)<<32 | a;
return 8;
}
p++;
a = a<<15;
a |= *p;
// a: p4<<29 | p6<<15 | p8 (unmasked)
// moved CSE2 up
// a &= (0x7f<<29)|(0x7f<<15)|(0xff);
b &= (0x7f<<14)|(0x7f);
b = b<<8;
a |= b;
s = s<<4;
b = p[-4];
b &= 0x7f;
b = b>>3;
s |= b;
*v = ((u64)s)<<32 | a;
return 9;
}
/*
** Read a 32-bit variable-length integer from memory starting at p[0].
** Return the number of bytes read. The value is stored in *v.
** A MACRO version, getVarint32, is provided which inlines the
** single-byte case. All code should use the MACRO version as
** this function assumes the single-byte case has already been handled.
*/
int sqlite3GetVarint32(const unsigned char *p, u32 *v){
u32 a,b;
a = *p;
// a: p0 (unmasked)
#ifndef getVarint32
if (!(a&0x80))
{
*v = a;
return 1;
}
#endif
p++;
b = *p;
// b: p1 (unmasked)
if (!(b&0x80))
{
a &= 0x7f;
a = a<<7;
*v = a | b;
return 2;
}
p++;
a = a<<14;
a |= *p;
// a: p0<<14 | p2 (unmasked)
if (!(a&0x80))
{
a &= (0x7f<<14)|(0x7f);
b &= 0x7f;
b = b<<7;
*v = a | b;
return 3;
}
p++;
b = b<<14;
b |= *p;
// b: p1<<14 | p3 (unmasked)
if (!(b&0x80))
{
b &= (0x7f<<14)|(0x7f);
a &= (0x7f<<14)|(0x7f);
a = a<<7;
*v = a | b;
return 4;
}
p++;
a = a<<14;
a |= *p;
// a: p0<<28 | p2<<14 | p4 (unmasked)
if (!(a&0x80))
{
a &= (0x7f<<28)|(0x7f<<14)|(0x7f);
b &= (0x7f<<28)|(0x7f<<14)|(0x7f);
b = b<<7;
*v = a | b;
return 5;
}
p++;
b = b<<14;
b |= *p;
// b: p1<<28 | p3<<14 | p5 (unmasked)
if (!(b&0x80))
{
b &= (0x7f<<28)|(0x7f<<14)|(0x7f);
a &= (0x7f<<28)|(0x7f<<14)|(0x7f);
a = a<<7;
*v = a | b;
return 6;
}
p++;
a = a<<14;
a |= *p;
// a: p2<<28 | p4<<14 | p6 (unmasked)
if (!(a&0x80))
{
a &= (0x7f<<28)|(0x7f<<14)|(0x7f);
b &= (0x7f<<28)|(0x7f<<14)|(0x7f);
b = b<<7;
*v = a | b;
return 7;
}
p++;
b = b<<14;
b |= *p;
// b: p3<<28 | p5<<14 | p7 (unmasked)
if (!(b&0x80))
{
b &= (0x7f<<28)|(0x7f<<14)|(0x7f);
a &= (0x7f<<28)|(0x7f<<14)|(0x7f);
a = a<<7;
*v = a | b;
return 8;
}
p++;
a = a<<14;
a |= *p;
// a: p4<<28 | p6<<14 | p8 (unmasked)
a &= (0x7f<<28)|(0x7f<<14)|(0x7f);
b &= (0x7f<<28)|(0x7f<<14)|(0x7f);
b = b<<7;
*v = a | b;
return 9;
}
/*
** Return the number of bytes that will be needed to store the given
** 64-bit integer.
*/
int sqlite3VarintLen(u64 v){
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