commit 56e7a15f6ffdae9e6b9c6929aeecfa71db9b1a73 from: Stefan Sperling date: Wed Mar 10 22:49:21 2021 UTC add deltify.c, unmodified from git9, with license header added commit - bc62ede807f0ad3a920fa1e8b05dd90cc8f5f289 commit + 56e7a15f6ffdae9e6b9c6929aeecfa71db9b1a73 blob - /dev/null blob + 2c65441387c0c94c073e56025c85edefba23def1 (mode 644) --- /dev/null +++ lib/deltify.c @@ -0,0 +1,241 @@ +/* + * Copyright (c) 2020 Ori Bernstein + * + * Permission is hereby granted, free of charge, to any person obtaining a copy + * of this software and associated documentation files (the "Software"), to deal + * in the Software without restriction, including without limitation the rights + * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell + * copies of the Software, and to permit persons to whom the Software is + * furnished to do so, subject to the following conditions: + * + * The above copyright notice and this permission notice shall be included in all + * copies or substantial portions of the Software. + * + * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR + * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, + * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE + * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER + * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, + * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE + * SOFTWARE. + */ + +#include +#include + +#include "git.h" + +enum { + Minchunk = 128, + Maxchunk = 8192, + Splitmask = (1<<8)-1, + +}; + +static u32int geartab[] = { + 0x67ed26b7, 0x32da500c, 0x53d0fee0, 0xce387dc7, 0xcd406d90, 0x2e83a4d4, 0x9fc9a38d, 0xb67259dc, + 0xca6b1722, 0x6d2ea08c, 0x235cea2e, 0x3149bb5f, 0x1beda787, 0x2a6b77d5, 0x2f22d9ac, 0x91fc0544, + 0xe413acfa, 0x5a30ff7a, 0xad6fdde0, 0x444fd0f5, 0x7ad87864, 0x58c5ff05, 0x8d2ec336, 0x2371f853, + 0x550f8572, 0x6aa448dd, 0x7c9ddbcf, 0x95221e14, 0x2a82ec33, 0xcbec5a78, 0xc6795a0d, 0x243995b7, + 0x1c909a2f, 0x4fded51c, 0x635d334b, 0x0e2b9999, 0x2702968d, 0x856de1d5, 0x3325d60e, 0xeb6a7502, + 0xec2a9844, 0x0905835a, 0xa1820375, 0xa4be5cab, 0x96a6c058, 0x2c2ccd70, 0xba40fce3, 0xd794c46b, + 0x8fbae83e, 0xc3aa7899, 0x3d3ff8ed, 0xa0d42b5b, 0x571c0c97, 0xd2811516, 0xf7e7b96c, 0x4fd2fcbd, + 0xe2fdec94, 0x282cc436, 0x78e8e95c, 0x80a3b613, 0xcfbee20c, 0xd4a32d1c, 0x2a12ff13, 0x6af82936, + 0xe5630258, 0x8efa6a98, 0x294fb2d1, 0xdeb57086, 0x5f0fddb3, 0xeceda7ce, 0x4c87305f, 0x3a6d3307, + 0xe22d2942, 0x9d060217, 0x1e42ed02, 0xb6f63b52, 0x4367f39f, 0x055cf262, 0x03a461b2, 0x5ef9e382, + 0x386bc03a, 0x2a1e79c7, 0xf1a0058b, 0xd4d2dea9, 0x56baf37d, 0x5daff6cc, 0xf03a951d, 0xaef7de45, + 0xa8f4581e, 0x3960b555, 0xffbfff6d, 0xbe702a23, 0x8f5b6d6f, 0x061739fb, 0x98696f47, 0x3fd596d4, + 0x151eac6b, 0xa9fcc4f5, 0x69181a12, 0x3ac5a107, 0xb5198fe7, 0x96bcb1da, 0x1b5ddf8e, 0xc757d650, + 0x65865c3a, 0x8fc0a41a, 0x87435536, 0x99eda6f2, 0x41874794, 0x29cff4e8, 0xb70efd9a, 0x3103f6e7, + 0x84d2453b, 0x15a450bd, 0x74f49af1, 0x60f664b1, 0xa1c86935, 0xfdafbce1, 0xe36353e3, 0x5d9ba739, + 0xbc0559ba, 0x708b0054, 0xd41d808c, 0xb2f31723, 0x9027c41f, 0xf136d165, 0xb5374b12, 0x9420a6ac, + 0x273958b6, 0xe6c2fad0, 0xebdc1f21, 0xfb33af8b, 0xc71c25cd, 0xe9a2d8e5, 0xbeb38a50, 0xbceb7cc2, + 0x4e4e73f0, 0xcd6c251d, 0xde4c032c, 0x4b04ac30, 0x725b8b21, 0x4eb8c33b, 0x20d07b75, 0x0567aa63, + 0xb56b2bb7, 0xc1f5fd3a, 0xcafd35ca, 0x470dd4da, 0xfe4f94cd, 0xfb8de424, 0xe8dbcf40, 0xfe50a37a, + 0x62db5b5d, 0xf32f4ab6, 0x2c4a8a51, 0x18473dc0, 0xfe0cbb6e, 0xfe399efd, 0xdf34ecc9, 0x6ccd5055, + 0x46097073, 0x139135c2, 0x721c76f6, 0x1c6a94b4, 0x6eee014d, 0x8a508e02, 0x3da538f5, 0x280d394f, + 0x5248a0c4, 0x3ce94c6c, 0x9a71ad3a, 0x8493dd05, 0xe43f0ab6, 0x18e4ed42, 0x6c5c0e09, 0x42b06ec9, + 0x8d330343, 0xa45b6f59, 0x2a573c0c, 0xd7fd3de6, 0xeedeab68, 0x5c84dafc, 0xbbd1b1a8, 0xa3ce1ad1, + 0x85b70bed, 0xb6add07f, 0xa531309c, 0x8f8ab852, 0x564de332, 0xeac9ed0c, 0x73da402c, 0x3ec52761, + 0x43af2f4d, 0xd6ff45c8, 0x4c367462, 0xd553bd6a, 0x44724855, 0x3b2aa728, 0x56e5eb65, 0xeaf16173, + 0x33fa42ff, 0xd714bb5d, 0xfbd0a3b9, 0xaf517134, 0x9416c8cd, 0x534cf94f, 0x548947c2, 0x34193569, + 0x32f4389a, 0xfe7028bc, 0xed73b1ed, 0x9db95770, 0x468e3922, 0x0440c3cd, 0x60059a62, 0x33504562, + 0x2b229fbd, 0x5174dca5, 0xf7028752, 0xd63c6aa8, 0x31276f38, 0x0646721c, 0xb0191da8, 0xe00e6de0, + 0x9eac1a6e, 0x9f7628a5, 0xed6c06ea, 0x0bb8af15, 0xf119fb12, 0x38693c1c, 0x732bc0fe, 0x84953275, + 0xb82ec888, 0x33a4f1b3, 0x3099835e, 0x028a8782, 0x5fdd51d7, 0xc6c717b3, 0xb06caf71, 0x17c8c111, + 0x61bad754, 0x9fd03061, 0xe09df1af, 0x3bc9eb73, 0x85878413, 0x9889aaf2, 0x3f5a9e46, 0x42c9f01f, + 0x9984a4f4, 0xd5de43cc, 0xd294daed, 0xbecba2d2, 0xf1f6e72c, 0x5551128a, 0x83af87e2, 0x6f0342ba, +}; + +static u64int +hash(void *p, int n) +{ + uchar buf[SHA1dlen]; + sha1((uchar*)p, n, buf, nil); + return GETBE64(buf); +} + +static void +addblk(Dtab *dt, void *buf, int len, int off, u64int h) +{ + int i, sz, probe; + Dblock *db; + + probe = h % dt->sz; + while(dt->b[probe].buf != nil){ + if(len == dt->b[probe].len && memcmp(buf, dt->b[probe].buf, len) == 0) + return; + probe = (probe + 1) % dt->sz; + } + assert(dt->b[probe].buf == nil); + dt->b[probe].buf = buf; + dt->b[probe].len = len; + dt->b[probe].off = off; + dt->b[probe].hash = h; + dt->nb++; + if(dt->sz < 2*dt->nb){ + sz = dt->sz; + db = dt->b; + dt->sz *= 2; + dt->nb = 0; + dt->b = eamalloc(dt->sz, sizeof(Dblock)); + for(i = 0; i < sz; i++) + if(db[i].buf != nil) + addblk(dt, db[i].buf, db[i].len, db[i].off, db[i].hash); + free(db); + } +} + +static Dblock* +lookup(Dtab *dt, uchar *p, int n) +{ + int probe; + u64int h; + + h = hash(p, n); + for(probe = h % dt->sz; dt->b[probe].buf != nil; probe = (probe + 1) % dt->sz){ + if(dt->b[probe].hash != h) + continue; + if(n != dt->b[probe].len) + continue; + if(memcmp(p, dt->b[probe].buf, n) != 0) + continue; + return &dt->b[probe]; + } + return nil; +} + +static int +nextblk(uchar *s, uchar *e) +{ + u32int gh; + uchar *p; + + if((e - s) < Minchunk) + return e - s; + p = s + Minchunk; + if((e - s) > Maxchunk) + e = s + Maxchunk; + gh = 0; + while(p != e){ + gh = (gh<<1) + geartab[*p++]; + if((gh & Splitmask) == 0) + break; + } + return p - s; +} + +void +dtinit(Dtab *dt, Object *obj) +{ + uchar *s, *e; + u64int h; + vlong n, o; + + o = 0; + s = (uchar*)obj->data; + e = s + obj->size; + dt->o = ref(obj); + dt->nb = 0; + dt->sz = 128; + dt->b = eamalloc(dt->sz, sizeof(Dblock)); + dt->base = (uchar*)obj->data; + dt->nbase = obj->size; + while(s != e){ + n = nextblk(s, e); + h = hash(s, n); + addblk(dt, s, n, o, h); + s += n; + o += n; + } +} + +void +dtclear(Dtab *dt) +{ + unref(dt->o); + free(dt->b); +} + +static int +emitdelta(Delta **pd, int *nd, int cpy, int off, int len) +{ + Delta *d; + + *nd += 1; + *pd = earealloc(*pd, *nd, sizeof(Delta)); + d = &(*pd)[*nd - 1]; + d->cpy = cpy; + d->off = off; + d->len = len; + return len; +} + +static int +stretch(Dtab *dt, Dblock *b, uchar *s, uchar *e, int n) +{ + uchar *p, *q, *eb; + + if(b == nil) + return n; + p = s + n; + q = dt->base + b->off + n; + eb = dt->base + dt->nbase; + while(n < (1<<24)){ + if(p == e || q == eb) + break; + if(*p != *q) + break; + p++; + q++; + n++; + } + return n; +} + +Delta* +deltify(Object *obj, Dtab *dt, int *pnd) +{ + Delta *d; + Dblock *b; + uchar *s, *e; + vlong n, o; + + o = 0; + d = nil; + s = (uchar*)obj->data; + e = s + obj->size; + *pnd = 0; + while(s != e){ + n = nextblk(s, e); + b = lookup(dt, s, n); + n = stretch(dt, b, s, e, n); + if(b != nil) + emitdelta(&d, pnd, 1, b->off, n); + else + emitdelta(&d, pnd, 0, o, n); + s += n; + o += n; + } + return d; +}