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author | Daniel Baumann <daniel.baumann@progress-linux.org> | 2024-04-11 08:27:49 +0000 |
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committer | Daniel Baumann <daniel.baumann@progress-linux.org> | 2024-04-11 08:27:49 +0000 |
commit | ace9429bb58fd418f0c81d4c2835699bddf6bde6 (patch) | |
tree | b2d64bc10158fdd5497876388cd68142ca374ed3 /lib/zlib_inflate/inffast.c | |
parent | Initial commit. (diff) | |
download | linux-ace9429bb58fd418f0c81d4c2835699bddf6bde6.tar.xz linux-ace9429bb58fd418f0c81d4c2835699bddf6bde6.zip |
Adding upstream version 6.6.15.upstream/6.6.15
Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>
Diffstat (limited to '')
-rw-r--r-- | lib/zlib_inflate/inffast.c | 341 |
1 files changed, 341 insertions, 0 deletions
diff --git a/lib/zlib_inflate/inffast.c b/lib/zlib_inflate/inffast.c new file mode 100644 index 0000000000..2843f9bb42 --- /dev/null +++ b/lib/zlib_inflate/inffast.c @@ -0,0 +1,341 @@ +/* inffast.c -- fast decoding + * Copyright (C) 1995-2004 Mark Adler + * For conditions of distribution and use, see copyright notice in zlib.h + */ + +#include <linux/zutil.h> +#include "inftrees.h" +#include "inflate.h" +#include "inffast.h" + +#ifndef ASMINF + +union uu { + unsigned short us; + unsigned char b[2]; +}; + +/* Endian independent version */ +static inline unsigned short +get_unaligned16(const unsigned short *p) +{ + union uu mm; + unsigned char *b = (unsigned char *)p; + + mm.b[0] = b[0]; + mm.b[1] = b[1]; + return mm.us; +} + +/* + Decode literal, length, and distance codes and write out the resulting + literal and match bytes until either not enough input or output is + available, an end-of-block is encountered, or a data error is encountered. + When large enough input and output buffers are supplied to inflate(), for + example, a 16K input buffer and a 64K output buffer, more than 95% of the + inflate execution time is spent in this routine. + + Entry assumptions: + + state->mode == LEN + strm->avail_in >= 6 + strm->avail_out >= 258 + start >= strm->avail_out + state->bits < 8 + + On return, state->mode is one of: + + LEN -- ran out of enough output space or enough available input + TYPE -- reached end of block code, inflate() to interpret next block + BAD -- error in block data + + Notes: + + - The maximum input bits used by a length/distance pair is 15 bits for the + length code, 5 bits for the length extra, 15 bits for the distance code, + and 13 bits for the distance extra. This totals 48 bits, or six bytes. + Therefore if strm->avail_in >= 6, then there is enough input to avoid + checking for available input while decoding. + + - The maximum bytes that a single length/distance pair can output is 258 + bytes, which is the maximum length that can be coded. inflate_fast() + requires strm->avail_out >= 258 for each loop to avoid checking for + output space. + + - @start: inflate()'s starting value for strm->avail_out + */ +void inflate_fast(z_streamp strm, unsigned start) +{ + struct inflate_state *state; + const unsigned char *in; /* local strm->next_in */ + const unsigned char *last; /* while in < last, enough input available */ + unsigned char *out; /* local strm->next_out */ + unsigned char *beg; /* inflate()'s initial strm->next_out */ + unsigned char *end; /* while out < end, enough space available */ +#ifdef INFLATE_STRICT + unsigned dmax; /* maximum distance from zlib header */ +#endif + unsigned wsize; /* window size or zero if not using window */ + unsigned whave; /* valid bytes in the window */ + unsigned write; /* window write index */ + unsigned char *window; /* allocated sliding window, if wsize != 0 */ + unsigned long hold; /* local strm->hold */ + unsigned bits; /* local strm->bits */ + code const *lcode; /* local strm->lencode */ + code const *dcode; /* local strm->distcode */ + unsigned lmask; /* mask for first level of length codes */ + unsigned dmask; /* mask for first level of distance codes */ + code this; /* retrieved table entry */ + unsigned op; /* code bits, operation, extra bits, or */ + /* window position, window bytes to copy */ + unsigned len; /* match length, unused bytes */ + unsigned dist; /* match distance */ + unsigned char *from; /* where to copy match from */ + + /* copy state to local variables */ + state = (struct inflate_state *)strm->state; + in = strm->next_in; + last = in + (strm->avail_in - 5); + out = strm->next_out; + beg = out - (start - strm->avail_out); + end = out + (strm->avail_out - 257); +#ifdef INFLATE_STRICT + dmax = state->dmax; +#endif + wsize = state->wsize; + whave = state->whave; + write = state->write; + window = state->window; + hold = state->hold; + bits = state->bits; + lcode = state->lencode; + dcode = state->distcode; + lmask = (1U << state->lenbits) - 1; + dmask = (1U << state->distbits) - 1; + + /* decode literals and length/distances until end-of-block or not enough + input data or output space */ + do { + if (bits < 15) { + hold += (unsigned long)(*in++) << bits; + bits += 8; + hold += (unsigned long)(*in++) << bits; + bits += 8; + } + this = lcode[hold & lmask]; + dolen: + op = (unsigned)(this.bits); + hold >>= op; + bits -= op; + op = (unsigned)(this.op); + if (op == 0) { /* literal */ + *out++ = (unsigned char)(this.val); + } + else if (op & 16) { /* length base */ + len = (unsigned)(this.val); + op &= 15; /* number of extra bits */ + if (op) { + if (bits < op) { + hold += (unsigned long)(*in++) << bits; + bits += 8; + } + len += (unsigned)hold & ((1U << op) - 1); + hold >>= op; + bits -= op; + } + if (bits < 15) { + hold += (unsigned long)(*in++) << bits; + bits += 8; + hold += (unsigned long)(*in++) << bits; + bits += 8; + } + this = dcode[hold & dmask]; + dodist: + op = (unsigned)(this.bits); + hold >>= op; + bits -= op; + op = (unsigned)(this.op); + if (op & 16) { /* distance base */ + dist = (unsigned)(this.val); + op &= 15; /* number of extra bits */ + if (bits < op) { + hold += (unsigned long)(*in++) << bits; + bits += 8; + if (bits < op) { + hold += (unsigned long)(*in++) << bits; + bits += 8; + } + } + dist += (unsigned)hold & ((1U << op) - 1); +#ifdef INFLATE_STRICT + if (dist > dmax) { + strm->msg = (char *)"invalid distance too far back"; + state->mode = BAD; + break; + } +#endif + hold >>= op; + bits -= op; + op = (unsigned)(out - beg); /* max distance in output */ + if (dist > op) { /* see if copy from window */ + op = dist - op; /* distance back in window */ + if (op > whave) { + strm->msg = (char *)"invalid distance too far back"; + state->mode = BAD; + break; + } + from = window; + if (write == 0) { /* very common case */ + from += wsize - op; + if (op < len) { /* some from window */ + len -= op; + do { + *out++ = *from++; + } while (--op); + from = out - dist; /* rest from output */ + } + } + else if (write < op) { /* wrap around window */ + from += wsize + write - op; + op -= write; + if (op < len) { /* some from end of window */ + len -= op; + do { + *out++ = *from++; + } while (--op); + from = window; + if (write < len) { /* some from start of window */ + op = write; + len -= op; + do { + *out++ = *from++; + } while (--op); + from = out - dist; /* rest from output */ + } + } + } + else { /* contiguous in window */ + from += write - op; + if (op < len) { /* some from window */ + len -= op; + do { + *out++ = *from++; + } while (--op); + from = out - dist; /* rest from output */ + } + } + while (len > 2) { + *out++ = *from++; + *out++ = *from++; + *out++ = *from++; + len -= 3; + } + if (len) { + *out++ = *from++; + if (len > 1) + *out++ = *from++; + } + } + else { + unsigned short *sout; + unsigned long loops; + + from = out - dist; /* copy direct from output */ + /* minimum length is three */ + /* Align out addr */ + if (!((long)(out - 1) & 1)) { + *out++ = *from++; + len--; + } + sout = (unsigned short *)(out); + if (dist > 2) { + unsigned short *sfrom; + + sfrom = (unsigned short *)(from); + loops = len >> 1; + do { + if (IS_ENABLED(CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS)) + *sout++ = *sfrom++; + else + *sout++ = get_unaligned16(sfrom++); + } while (--loops); + out = (unsigned char *)sout; + from = (unsigned char *)sfrom; + } else { /* dist == 1 or dist == 2 */ + unsigned short pat16; + + pat16 = *(sout-1); + if (dist == 1) { + union uu mm; + /* copy one char pattern to both bytes */ + mm.us = pat16; + mm.b[0] = mm.b[1]; + pat16 = mm.us; + } + loops = len >> 1; + do + *sout++ = pat16; + while (--loops); + out = (unsigned char *)sout; + } + if (len & 1) + *out++ = *from++; + } + } + else if ((op & 64) == 0) { /* 2nd level distance code */ + this = dcode[this.val + (hold & ((1U << op) - 1))]; + goto dodist; + } + else { + strm->msg = (char *)"invalid distance code"; + state->mode = BAD; + break; + } + } + else if ((op & 64) == 0) { /* 2nd level length code */ + this = lcode[this.val + (hold & ((1U << op) - 1))]; + goto dolen; + } + else if (op & 32) { /* end-of-block */ + state->mode = TYPE; + break; + } + else { + strm->msg = (char *)"invalid literal/length code"; + state->mode = BAD; + break; + } + } while (in < last && out < end); + + /* return unused bytes (on entry, bits < 8, so in won't go too far back) */ + len = bits >> 3; + in -= len; + bits -= len << 3; + hold &= (1U << bits) - 1; + + /* update state and return */ + strm->next_in = in; + strm->next_out = out; + strm->avail_in = (unsigned)(in < last ? 5 + (last - in) : 5 - (in - last)); + strm->avail_out = (unsigned)(out < end ? + 257 + (end - out) : 257 - (out - end)); + state->hold = hold; + state->bits = bits; + return; +} + +/* + inflate_fast() speedups that turned out slower (on a PowerPC G3 750CXe): + - Using bit fields for code structure + - Different op definition to avoid & for extra bits (do & for table bits) + - Three separate decoding do-loops for direct, window, and write == 0 + - Special case for distance > 1 copies to do overlapped load and store copy + - Explicit branch predictions (based on measured branch probabilities) + - Deferring match copy and interspersed it with decoding subsequent codes + - Swapping literal/length else + - Swapping window/direct else + - Larger unrolled copy loops (three is about right) + - Moving len -= 3 statement into middle of loop + */ + +#endif /* !ASMINF */ |