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/* chunkcopy.h -- fast chunk copy and set operations
* Copyright (C) 2017 ARM, Inc.
* Copyright 2017 The Chromium Authors. All rights reserved.
* Use of this source code is governed by a BSD-style license that can be
* found in the Chromium source repository LICENSE file.
*/
#ifndef CHUNKCOPY_H
#define CHUNKCOPY_H
#include <stdint.h>
#include "zutil.h"
#define Z_STATIC_ASSERT(name, assert) typedef char name[(assert) ? 1 : -1]
#if __STDC_VERSION__ >= 199901L
#define Z_RESTRICT restrict
#else
#define Z_RESTRICT
#endif
#if defined(__clang__) || defined(__GNUC__) || defined(__llvm__)
#define Z_BUILTIN_MEMCPY __builtin_memcpy
#else
#define Z_BUILTIN_MEMCPY zmemcpy
#endif
#if defined(INFLATE_CHUNK_SIMD_NEON)
#include <arm_neon.h>
typedef uint8x16_t z_vec128i_t;
#elif defined(INFLATE_CHUNK_SIMD_SSE2)
#include <emmintrin.h>
typedef __m128i z_vec128i_t;
#else
#error chunkcopy.h inflate chunk SIMD is not defined for your build target
#endif
/*
* chunk copy type: the z_vec128i_t type size should be exactly 128-bits
* and equal to CHUNKCOPY_CHUNK_SIZE.
*/
#define CHUNKCOPY_CHUNK_SIZE sizeof(z_vec128i_t)
Z_STATIC_ASSERT(vector_128_bits_wide,
CHUNKCOPY_CHUNK_SIZE == sizeof(int8_t) * 16);
/*
* Ask the compiler to perform a wide, unaligned load with a machine
* instruction appropriate for the z_vec128i_t type.
*/
static inline z_vec128i_t loadchunk(
const unsigned char FAR* s) {
z_vec128i_t v;
Z_BUILTIN_MEMCPY(&v, s, sizeof(v));
return v;
}
/*
* Ask the compiler to perform a wide, unaligned store with a machine
* instruction appropriate for the z_vec128i_t type.
*/
static inline void storechunk(
unsigned char FAR* d,
const z_vec128i_t v) {
Z_BUILTIN_MEMCPY(d, &v, sizeof(v));
}
/*
* Perform a memcpy-like operation, assuming that length is non-zero and that
* it's OK to overwrite at least CHUNKCOPY_CHUNK_SIZE bytes of output even if
* the length is shorter than this.
*
* It also guarantees that it will properly unroll the data if the distance
* between `out` and `from` is at least CHUNKCOPY_CHUNK_SIZE, which we rely on
* in chunkcopy_relaxed().
*
* Aside from better memory bus utilisation, this means that short copies
* (CHUNKCOPY_CHUNK_SIZE bytes or fewer) will fall straight through the loop
* without iteration, which will hopefully make the branch prediction more
* reliable.
*/
static inline unsigned char FAR* chunkcopy_core(
unsigned char FAR* out,
const unsigned char FAR* from,
unsigned len) {
const int bump = (--len % CHUNKCOPY_CHUNK_SIZE) + 1;
storechunk(out, loadchunk(from));
out += bump;
from += bump;
len /= CHUNKCOPY_CHUNK_SIZE;
while (len-- > 0) {
storechunk(out, loadchunk(from));
out += CHUNKCOPY_CHUNK_SIZE;
from += CHUNKCOPY_CHUNK_SIZE;
}
return out;
}
/*
* Like chunkcopy_core(), but avoid writing beyond of legal output.
*
* Accepts an additional pointer to the end of safe output. A generic safe
* copy would use (out + len), but it's normally the case that the end of the
* output buffer is beyond the end of the current copy, and this can still be
* exploited.
*/
static inline unsigned char FAR* chunkcopy_core_safe(
unsigned char FAR* out,
const unsigned char FAR* from,
unsigned len,
unsigned char FAR* limit) {
Assert(out + len <= limit, "chunk copy exceeds safety limit");
if ((limit - out) < (ptrdiff_t)CHUNKCOPY_CHUNK_SIZE) {
const unsigned char FAR* Z_RESTRICT rfrom = from;
if (len & 8) {
Z_BUILTIN_MEMCPY(out, rfrom, 8);
out += 8;
rfrom += 8;
}
if (len & 4) {
Z_BUILTIN_MEMCPY(out, rfrom, 4);
out += 4;
rfrom += 4;
}
if (len & 2) {
Z_BUILTIN_MEMCPY(out, rfrom, 2);
out += 2;
rfrom += 2;
}
if (len & 1) {
*out++ = *rfrom++;
}
return out;
}
return chunkcopy_core(out, from, len);
}
/*
* Perform short copies until distance can be rewritten as being at least
* CHUNKCOPY_CHUNK_SIZE.
*
* Assumes it's OK to overwrite at least the first 2*CHUNKCOPY_CHUNK_SIZE
* bytes of output even if the copy is shorter than this. This assumption
* holds within zlib inflate_fast(), which starts every iteration with at
* least 258 bytes of output space available (258 being the maximum length
* output from a single token; see inffast.c).
*/
static inline unsigned char FAR* chunkunroll_relaxed(
unsigned char FAR* out,
unsigned FAR* dist,
unsigned FAR* len) {
const unsigned char FAR* from = out - *dist;
while (*dist < *len && *dist < CHUNKCOPY_CHUNK_SIZE) {
storechunk(out, loadchunk(from));
out += *dist;
*len -= *dist;
*dist += *dist;
}
return out;
}
#if defined(INFLATE_CHUNK_SIMD_NEON)
/*
* v_load64_dup(): load *src as an unaligned 64-bit int and duplicate it in
* every 64-bit component of the 128-bit result (64-bit int splat).
*/
static inline z_vec128i_t v_load64_dup(const void* src) {
return vcombine_u8(vld1_u8(src), vld1_u8(src));
}
/*
* v_load32_dup(): load *src as an unaligned 32-bit int and duplicate it in
* every 32-bit component of the 128-bit result (32-bit int splat).
*/
static inline z_vec128i_t v_load32_dup(const void* src) {
int32_t i32;
Z_BUILTIN_MEMCPY(&i32, src, sizeof(i32));
return vreinterpretq_u8_s32(vdupq_n_s32(i32));
}
/*
* v_load16_dup(): load *src as an unaligned 16-bit int and duplicate it in
* every 16-bit component of the 128-bit result (16-bit int splat).
*/
static inline z_vec128i_t v_load16_dup(const void* src) {
int16_t i16;
Z_BUILTIN_MEMCPY(&i16, src, sizeof(i16));
return vreinterpretq_u8_s16(vdupq_n_s16(i16));
}
/*
* v_load8_dup(): load the 8-bit int *src and duplicate it in every 8-bit
* component of the 128-bit result (8-bit int splat).
*/
static inline z_vec128i_t v_load8_dup(const void* src) {
return vld1q_dup_u8((const uint8_t*)src);
}
/*
* v_store_128(): store the 128-bit vec in a memory destination (that might
* not be 16-byte aligned) void* out.
*/
static inline void v_store_128(void* out, const z_vec128i_t vec) {
vst1q_u8(out, vec);
}
#elif defined(INFLATE_CHUNK_SIMD_SSE2)
/*
* v_load64_dup(): load *src as an unaligned 64-bit int and duplicate it in
* every 64-bit component of the 128-bit result (64-bit int splat).
*/
static inline z_vec128i_t v_load64_dup(const void* src) {
int64_t i64;
Z_BUILTIN_MEMCPY(&i64, src, sizeof(i64));
return _mm_set1_epi64x(i64);
}
/*
* v_load32_dup(): load *src as an unaligned 32-bit int and duplicate it in
* every 32-bit component of the 128-bit result (32-bit int splat).
*/
static inline z_vec128i_t v_load32_dup(const void* src) {
int32_t i32;
Z_BUILTIN_MEMCPY(&i32, src, sizeof(i32));
return _mm_set1_epi32(i32);
}
/*
* v_load16_dup(): load *src as an unaligned 16-bit int and duplicate it in
* every 16-bit component of the 128-bit result (16-bit int splat).
*/
static inline z_vec128i_t v_load16_dup(const void* src) {
int16_t i16;
Z_BUILTIN_MEMCPY(&i16, src, sizeof(i16));
return _mm_set1_epi16(i16);
}
/*
* v_load8_dup(): load the 8-bit int *src and duplicate it in every 8-bit
* component of the 128-bit result (8-bit int splat).
*/
static inline z_vec128i_t v_load8_dup(const void* src) {
return _mm_set1_epi8(*(const char*)src);
}
/*
* v_store_128(): store the 128-bit vec in a memory destination (that might
* not be 16-byte aligned) void* out.
*/
static inline void v_store_128(void* out, const z_vec128i_t vec) {
_mm_storeu_si128((__m128i*)out, vec);
}
#endif
/*
* Perform an overlapping copy which behaves as a memset() operation, but
* supporting periods other than one, and assume that length is non-zero and
* that it's OK to overwrite at least CHUNKCOPY_CHUNK_SIZE*3 bytes of output
* even if the length is shorter than this.
*/
static inline unsigned char FAR* chunkset_core(
unsigned char FAR* out,
unsigned period,
unsigned len) {
z_vec128i_t v;
const int bump = ((len - 1) % sizeof(v)) + 1;
switch (period) {
case 1:
v = v_load8_dup(out - 1);
v_store_128(out, v);
out += bump;
len -= bump;
while (len > 0) {
v_store_128(out, v);
out += sizeof(v);
len -= sizeof(v);
}
return out;
case 2:
v = v_load16_dup(out - 2);
v_store_128(out, v);
out += bump;
len -= bump;
if (len > 0) {
v = v_load16_dup(out - 2);
do {
v_store_128(out, v);
out += sizeof(v);
len -= sizeof(v);
} while (len > 0);
}
return out;
case 4:
v = v_load32_dup(out - 4);
v_store_128(out, v);
out += bump;
len -= bump;
if (len > 0) {
v = v_load32_dup(out - 4);
do {
v_store_128(out, v);
out += sizeof(v);
len -= sizeof(v);
} while (len > 0);
}
return out;
case 8:
v = v_load64_dup(out - 8);
v_store_128(out, v);
out += bump;
len -= bump;
if (len > 0) {
v = v_load64_dup(out - 8);
do {
v_store_128(out, v);
out += sizeof(v);
len -= sizeof(v);
} while (len > 0);
}
return out;
}
out = chunkunroll_relaxed(out, &period, &len);
return chunkcopy_core(out, out - period, len);
}
/*
* Perform a memcpy-like operation, but assume that length is non-zero and that
* it's OK to overwrite at least CHUNKCOPY_CHUNK_SIZE bytes of output even if
* the length is shorter than this.
*
* Unlike chunkcopy_core() above, no guarantee is made regarding the behaviour
* of overlapping buffers, regardless of the distance between the pointers.
* This is reflected in the `restrict`-qualified pointers, allowing the
* compiler to re-order loads and stores.
*/
static inline unsigned char FAR* chunkcopy_relaxed(
unsigned char FAR* Z_RESTRICT out,
const unsigned char FAR* Z_RESTRICT from,
unsigned len) {
return chunkcopy_core(out, from, len);
}
/*
* Like chunkcopy_relaxed(), but avoid writing beyond of legal output.
*
* Unlike chunkcopy_core_safe() above, no guarantee is made regarding the
* behaviour of overlapping buffers, regardless of the distance between the
* pointers. This is reflected in the `restrict`-qualified pointers, allowing
* the compiler to re-order loads and stores.
*
* Accepts an additional pointer to the end of safe output. A generic safe
* copy would use (out + len), but it's normally the case that the end of the
* output buffer is beyond the end of the current copy, and this can still be
* exploited.
*/
static inline unsigned char FAR* chunkcopy_safe(
unsigned char FAR* out,
const unsigned char FAR* Z_RESTRICT from,
unsigned len,
unsigned char FAR* limit) {
Assert(out + len <= limit, "chunk copy exceeds safety limit");
return chunkcopy_core_safe(out, from, len, limit);
}
/*
* Perform chunky copy within the same buffer, where the source and destination
* may potentially overlap.
*
* Assumes that len > 0 on entry, and that it's safe to write at least
* CHUNKCOPY_CHUNK_SIZE*3 bytes to the output.
*/
static inline unsigned char FAR* chunkcopy_lapped_relaxed(
unsigned char FAR* out,
unsigned dist,
unsigned len) {
if (dist < len && dist < CHUNKCOPY_CHUNK_SIZE) {
return chunkset_core(out, dist, len);
}
return chunkcopy_core(out, out - dist, len);
}
/*
* Behave like chunkcopy_lapped_relaxed(), but avoid writing beyond of legal
* output.
*
* Accepts an additional pointer to the end of safe output. A generic safe
* copy would use (out + len), but it's normally the case that the end of the
* output buffer is beyond the end of the current copy, and this can still be
* exploited.
*/
static inline unsigned char FAR* chunkcopy_lapped_safe(
unsigned char FAR* out,
unsigned dist,
unsigned len,
unsigned char FAR* limit) {
Assert(out + len <= limit, "chunk copy exceeds safety limit");
if ((limit - out) < (ptrdiff_t)(3 * CHUNKCOPY_CHUNK_SIZE)) {
/* TODO(cavalcantii): try harder to optimise this */
while (len-- > 0) {
*out = *(out - dist);
out++;
}
return out;
}
return chunkcopy_lapped_relaxed(out, dist, len);
}
/*
* The chunk-copy code above deals with writing the decoded DEFLATE data to
* the output with SIMD methods to increase decode speed. Reading the input
* to the DEFLATE decoder with a wide, SIMD method can also increase decode
* speed. This option is supported on little endian machines, and reads the
* input data in 64-bit (8 byte) chunks.
*/
#ifdef INFLATE_CHUNK_READ_64LE
/*
* Buffer the input in a uint64_t (8 bytes) in the wide input reading case.
*/
typedef uint64_t inflate_holder_t;
/*
* Ask the compiler to perform a wide, unaligned load of a uint64_t using a
* machine instruction appropriate for the uint64_t type.
*/
static inline inflate_holder_t read64le(const unsigned char FAR *in) {
inflate_holder_t input;
Z_BUILTIN_MEMCPY(&input, in, sizeof(input));
return input;
}
#else
/*
* Otherwise, buffer the input bits using zlib's default input buffer type.
*/
typedef unsigned long inflate_holder_t;
#endif /* INFLATE_CHUNK_READ_64LE */
#undef Z_STATIC_ASSERT
#undef Z_RESTRICT
#undef Z_BUILTIN_MEMCPY
#endif /* CHUNKCOPY_H */