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Songlx516
8bee84bd49
Groundwork for 7z support (the second of the six format x volume
combinations). No engine code yet: this lands the vendor subset, real
fixtures and the end-to-end driver, so the engine has something to be
built and checked against.
Vendor (third_party/7z, LZMA SDK 26.03, public domain):
- decoder-only subset: 7zArcIn/7zDec container, Lzma/Lzma2/Ppmd7/Bcj2/
Bra/Delta codecs, Aes/Sha256 for the password channel to come
- the encoder half (LzmaEnc, Xz*, Sort, Threads, ...) is deliberately
not vendored; the engine never encodes
- README.md records two SDK limitations that shape the engine design:
* CSzFolder caps a folder at 4 coders / 3 bonds, so 7-Zip's own BCJ2
chain (BCJ2 + 4xLZMA2 = 5 coders) is refused by SzAr_DecodeFolder
even though SzArEx_Open parses it happily - the engine therefore
parses folder blobs and drives the codec chain itself
* the C decoder ships no 7zAES coder at all, so both -p and -mhe=on
archives are rejected until the engine implements it on top of the
vendored Aes.c / Sha256.c
Tests:
- make_sevenz_fixtures.py builds real archives with an actual 7-Zip
binary (7za from the Extra package; falls back to the reduced 7zr,
which has no PPMd encoder): store/lzma/lzma2/ppmd/bcj/delta/bcj2,
AES with plain and with encrypted headers, a 7-part -v100k volume
set, and UTF-8 entry names
- sevenz_e2e.c extracts an archive and validates every entry against
the stored CRC; it calls the wide-character file APIs on Windows, so
non-ASCII entry names are really created instead of silently failing
- run-sevenz-tests.sh builds the subset and the driver, then runs the
fixture matrix with an explicit KNOWN_GAPS list that fails loudly
when one of the gaps starts passing
Status: store, lzma, lzma2, ppmd, bcj, delta and utf8 all extract
byte-identical to the source tree (7/10). bcj2, aes, aeshe and
vol.7z.001 are the known gaps, each mapped to a specific piece of
engine work still to come.
170 lines
3.0 KiB
C
170 lines
3.0 KiB
C
/* Delta.c -- Delta converter
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2021-02-09 : Igor Pavlov : Public domain */
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#include "Precomp.h"
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#include "Delta.h"
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void Delta_Init(Byte *state)
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{
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unsigned i;
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for (i = 0; i < DELTA_STATE_SIZE; i++)
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state[i] = 0;
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}
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void Delta_Encode(Byte *state, unsigned delta, Byte *data, SizeT size)
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{
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Byte temp[DELTA_STATE_SIZE];
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if (size == 0)
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return;
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{
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unsigned i = 0;
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do
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temp[i] = state[i];
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while (++i != delta);
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}
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if (size <= delta)
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{
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unsigned i = 0, k;
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do
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{
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Byte b = *data;
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*data++ = (Byte)(b - temp[i]);
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temp[i] = b;
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}
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while (++i != size);
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k = 0;
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do
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{
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if (i == delta)
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i = 0;
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state[k] = temp[i++];
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}
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while (++k != delta);
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return;
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}
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{
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Byte *p = data + size - delta;
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{
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unsigned i = 0;
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do
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state[i] = *p++;
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while (++i != delta);
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}
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{
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const Byte *lim = data + delta;
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ptrdiff_t dif = -(ptrdiff_t)delta;
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if (((ptrdiff_t)size + dif) & 1)
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{
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--p; *p = (Byte)(*p - p[dif]);
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}
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while (p != lim)
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{
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--p; *p = (Byte)(*p - p[dif]);
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--p; *p = (Byte)(*p - p[dif]);
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}
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dif = -dif;
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do
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{
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--p; *p = (Byte)(*p - temp[--dif]);
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}
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while (dif != 0);
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}
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}
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}
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void Delta_Decode(Byte *state, unsigned delta, Byte *data, SizeT size)
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{
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unsigned i;
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const Byte *lim;
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if (size == 0)
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return;
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i = 0;
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lim = data + size;
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if (size <= delta)
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{
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do
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*data = (Byte)(*data + state[i++]);
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while (++data != lim);
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for (; delta != i; state++, delta--)
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*state = state[i];
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data -= i;
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}
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else
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{
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/*
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#define B(n) b ## n
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#define I(n) Byte B(n) = state[n];
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#define U(n) { B(n) = (Byte)((B(n)) + *data++); data[-1] = (B(n)); }
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#define F(n) if (data != lim) { U(n) }
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if (delta == 1)
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{
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I(0)
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if ((lim - data) & 1) { U(0) }
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while (data != lim) { U(0) U(0) }
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data -= 1;
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}
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else if (delta == 2)
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{
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I(0) I(1)
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lim -= 1; while (data < lim) { U(0) U(1) }
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lim += 1; F(0)
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data -= 2;
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}
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else if (delta == 3)
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{
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I(0) I(1) I(2)
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lim -= 2; while (data < lim) { U(0) U(1) U(2) }
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lim += 2; F(0) F(1)
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data -= 3;
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}
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else if (delta == 4)
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{
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I(0) I(1) I(2) I(3)
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lim -= 3; while (data < lim) { U(0) U(1) U(2) U(3) }
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lim += 3; F(0) F(1) F(2)
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data -= 4;
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}
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else
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*/
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{
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do
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{
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*data = (Byte)(*data + state[i++]);
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data++;
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}
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while (i != delta);
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{
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ptrdiff_t dif = -(ptrdiff_t)delta;
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do
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*data = (Byte)(*data + data[dif]);
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while (++data != lim);
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data += dif;
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}
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}
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}
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do
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*state++ = *data;
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while (++data != lim);
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}
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