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https://gitlab.isc.org/isc-projects/bind9
synced 2025-08-31 06:25:31 +00:00
Optimize rdataset_getownercase not to use bitshifts
The last rdataset_getownercase() left it in a state where the code was mix of microoptimizations (manual loop unrolling, complicated bitshifts) with a code that would always rewrite the character even if it stayed the same after transformation. This commit makes sure that we modify only the characters that actually need to change, removes the manual loop unrolling, and replaces the weird bit arithmetics with a simple shift and bit-and.
This commit is contained in:
Ondřej Surý
162
lib/dns/rbtdb.c
162
lib/dns/rbtdb.c
@@ -9848,7 +9848,7 @@ setownercase(rdatasetheader_t *header, const dns_name_t *name) {
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memset(header->upper, 0, sizeof(header->upper));
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fully_lower = true;
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for (i = 0; i < name->length; i++) {
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if (name->ndata[i] >= 0x41 && name->ndata[i] <= 0x5a) {
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if (name->ndata[i] >= 'A' && name->ndata[i] <= 'Z') {
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{
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header->upper[i / 8] |= 1 << (i % 8);
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fully_lower = false;
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@@ -9877,54 +9877,20 @@ rdataset_setownercase(dns_rdataset_t *rdataset, const dns_name_t *name) {
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isc_rwlocktype_write);
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}
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static const unsigned char charmask[] = {
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0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
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0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
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0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
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0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
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0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
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0x00, 0x00, 0x00, 0x00, 0x00, 0x20, 0x20, 0x20, 0x20, 0x20, 0x20, 0x20,
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0x20, 0x20, 0x20, 0x20, 0x20, 0x20, 0x20, 0x20, 0x20, 0x20, 0x20, 0x20,
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0x20, 0x20, 0x20, 0x20, 0x20, 0x20, 0x20, 0x00, 0x00, 0x00, 0x00, 0x00,
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0x00, 0x20, 0x20, 0x20, 0x20, 0x20, 0x20, 0x20, 0x20, 0x20, 0x20, 0x20,
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0x20, 0x20, 0x20, 0x20, 0x20, 0x20, 0x20, 0x20, 0x20, 0x20, 0x20, 0x20,
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0x20, 0x20, 0x20, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
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0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
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0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
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0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
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0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
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0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
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0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
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0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
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0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
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0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
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0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
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0x00, 0x00, 0x00, 0x00
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static const unsigned char maptolower[256] = {
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['A'] = 'a', ['B'] = 'b', ['C'] = 'c', ['D'] = 'd', ['E'] = 'e',
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['F'] = 'f', ['G'] = 'g', ['H'] = 'h', ['I'] = 'i', ['J'] = 'j',
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['K'] = 'k', ['L'] = 'l', ['M'] = 'm', ['N'] = 'n', ['O'] = 'o',
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['P'] = 'p', ['Q'] = 'q', ['R'] = 'r', ['S'] = 's', ['T'] = 't',
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['U'] = 'u', ['V'] = 'v', ['X'] = 'x', ['Y'] = 'y', ['Z'] = 'z',
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};
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static const unsigned char maptolower[] = {
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0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07, 0x08, 0x09, 0x0a, 0x0b,
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0x0c, 0x0d, 0x0e, 0x0f, 0x10, 0x11, 0x12, 0x13, 0x14, 0x15, 0x16, 0x17,
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0x18, 0x19, 0x1a, 0x1b, 0x1c, 0x1d, 0x1e, 0x1f, 0x20, 0x21, 0x22, 0x23,
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0x24, 0x25, 0x26, 0x27, 0x28, 0x29, 0x2a, 0x2b, 0x2c, 0x2d, 0x2e, 0x2f,
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0x30, 0x31, 0x32, 0x33, 0x34, 0x35, 0x36, 0x37, 0x38, 0x39, 0x3a, 0x3b,
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0x3c, 0x3d, 0x3e, 0x3f, 0x40, 0x61, 0x62, 0x63, 0x64, 0x65, 0x66, 0x67,
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0x68, 0x69, 0x6a, 0x6b, 0x6c, 0x6d, 0x6e, 0x6f, 0x70, 0x71, 0x72, 0x73,
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0x74, 0x75, 0x76, 0x77, 0x78, 0x79, 0x7a, 0x5b, 0x5c, 0x5d, 0x5e, 0x5f,
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0x60, 0x61, 0x62, 0x63, 0x64, 0x65, 0x66, 0x67, 0x68, 0x69, 0x6a, 0x6b,
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0x6c, 0x6d, 0x6e, 0x6f, 0x70, 0x71, 0x72, 0x73, 0x74, 0x75, 0x76, 0x77,
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0x78, 0x79, 0x7a, 0x7b, 0x7c, 0x7d, 0x7e, 0x7f, 0x80, 0x81, 0x82, 0x83,
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0x84, 0x85, 0x86, 0x87, 0x88, 0x89, 0x8a, 0x8b, 0x8c, 0x8d, 0x8e, 0x8f,
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0x90, 0x91, 0x92, 0x93, 0x94, 0x95, 0x96, 0x97, 0x98, 0x99, 0x9a, 0x9b,
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0x9c, 0x9d, 0x9e, 0x9f, 0xa0, 0xa1, 0xa2, 0xa3, 0xa4, 0xa5, 0xa6, 0xa7,
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0xa8, 0xa9, 0xaa, 0xab, 0xac, 0xad, 0xae, 0xaf, 0xb0, 0xb1, 0xb2, 0xb3,
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0xb4, 0xb5, 0xb6, 0xb7, 0xb8, 0xb9, 0xba, 0xbb, 0xbc, 0xbd, 0xbe, 0xbf,
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0xc0, 0xc1, 0xc2, 0xc3, 0xc4, 0xc5, 0xc6, 0xc7, 0xc8, 0xc9, 0xca, 0xcb,
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0xcc, 0xcd, 0xce, 0xcf, 0xd0, 0xd1, 0xd2, 0xd3, 0xd4, 0xd5, 0xd6, 0xd7,
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0xd8, 0xd9, 0xda, 0xdb, 0xdc, 0xdd, 0xde, 0xdf, 0xe0, 0xe1, 0xe2, 0xe3,
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0xe4, 0xe5, 0xe6, 0xe7, 0xe8, 0xe9, 0xea, 0xeb, 0xec, 0xed, 0xee, 0xef,
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0xf0, 0xf1, 0xf2, 0xf3, 0xf4, 0xf5, 0xf6, 0xf7, 0xf8, 0xf9, 0xfa, 0xfb,
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0xfc, 0xfd, 0xfe, 0xff
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static const unsigned char maptoupper[256] = {
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['a'] = 'A', ['b'] = 'B', ['c'] = 'C', ['d'] = 'D', ['e'] = 'E',
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['f'] = 'F', ['g'] = 'G', ['h'] = 'H', ['i'] = 'I', ['j'] = 'J',
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['k'] = 'K', ['l'] = 'L', ['m'] = 'M', ['n'] = 'N', ['o'] = 'O',
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['p'] = 'P', ['q'] = 'Q', ['r'] = 'R', ['s'] = 'S', ['t'] = 'T',
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['u'] = 'U', ['v'] = 'V', ['x'] = 'X', ['y'] = 'Y', ['z'] = 'Z',
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};
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static void
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@@ -9932,10 +9898,9 @@ rdataset_getownercase(const dns_rdataset_t *rdataset, dns_name_t *name) {
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dns_rbtdb_t *rbtdb = rdataset->private1;
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dns_rbtnode_t *rbtnode = rdataset->private2;
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unsigned char *raw = rdataset->private3; /* RDATASLAB */
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rdatasetheader_t *header;
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unsigned int i, j;
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unsigned char bits;
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unsigned char c, flip;
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rdatasetheader_t *header = NULL;
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uint8_t mask = (1 << 7);
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uint8_t bits = 0;
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header = (struct rdatasetheader *)(raw - sizeof(*header));
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@@ -9946,85 +9911,36 @@ rdataset_getownercase(const dns_rdataset_t *rdataset, dns_name_t *name) {
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goto unlock;
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}
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#if 0
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/*
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* This was the original code, and is implemented differently in
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* the #else block that follows.
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*/
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for (i = 0; i < name->length; i++) {
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/*
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* Set the case bit if it does not match the recorded bit.
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*/
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if (name->ndata[i] >= 0x61 && name->ndata[i] <= 0x7a &&
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(header->upper[i / 8] & (1 << (i % 8))) != 0)
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{
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name->ndata[i] &= ~0x20; /* clear the lower case bit */
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} else if (name->ndata[i] >= 0x41 && name->ndata[i] <= 0x5a &&
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(header->upper[i / 8] & (1 << (i % 8))) == 0)
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{
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name->ndata[i] |= 0x20; /* set the lower case bit */
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}
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}
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#else /* if 0 */
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if (ISC_LIKELY(CASEFULLYLOWER(header))) {
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unsigned char *bp, *be;
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bp = name->ndata;
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be = bp + name->length;
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while (bp <= be - 4) {
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c = bp[0];
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bp[0] = maptolower[c];
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c = bp[1];
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bp[1] = maptolower[c];
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c = bp[2];
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bp[2] = maptolower[c];
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c = bp[3];
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bp[3] = maptolower[c];
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bp += 4;
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for (size_t i = 0; i < name->length; i++) {
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uint8_t c = name->ndata[i];
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if (c >= 'A' && c <= 'Z') {
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name->ndata[i] = maptolower[c];
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}
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}
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while (bp < be) {
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c = *bp;
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*bp++ = maptolower[c];
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}
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goto unlock;
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}
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} else {
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for (size_t i = 0; i < name->length; i++) {
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uint8_t c = name->ndata[i];
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i = 0;
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for (j = 0; j < (name->length >> 3); j++) {
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unsigned int k;
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if (mask == (1 << 7)) {
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bits = header->upper[i / 8];
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mask = 1;
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} else {
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mask <<= 1;
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}
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bits = ~(header->upper[j]);
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for (k = 0; k < 8; k++) {
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c = name->ndata[i];
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flip = (bits & 1) << 5;
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flip ^= c;
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flip &= charmask[c];
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name->ndata[i] ^= flip;
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i++;
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bits >>= 1;
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if (c >= 'a' && c <= 'z') {
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if ((bits & mask) != 0) {
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name->ndata[i] = maptoupper[c];
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}
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} else if (c >= 'A' && c <= 'Z') {
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if ((bits & mask) == 0) {
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name->ndata[i] = maptolower[c];
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}
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}
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}
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}
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if (ISC_UNLIKELY(i == name->length)) {
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goto unlock;
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}
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bits = ~(header->upper[j]);
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for (; i < name->length; i++) {
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c = name->ndata[i];
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flip = (bits & 1) << 5;
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flip ^= c;
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flip &= charmask[c];
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name->ndata[i] ^= flip;
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bits >>= 1;
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}
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#endif /* if 0 */
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unlock:
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NODE_UNLOCK(&rbtdb->node_locks[rbtnode->locknum].lock,
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isc_rwlocktype_read);
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