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+/* chunkcopy.h -- fast chunk copy and set operations
+ *
+ * (C) 1995-2013 Jean-loup Gailly and Mark Adler
+ *
+ * This software is provided 'as-is', without any express or implied
+ * warranty. In no event will the authors be held liable for any damages
+ * arising from the use of this software.
+ *
+ * Permission is granted to anyone to use this software for any purpose,
+ * including commercial applications, and to alter it and redistribute it
+ * freely, subject to the following restrictions:
+ *
+ * 1. The origin of this software must not be misrepresented; you must not
+ * claim that you wrote the original software. If you use this software
+ * in a product, an acknowledgment in the product documentation would be
+ * appreciated but is not required.
+ * 2. Altered source versions must be plainly marked as such, and must not be
+ * misrepresented as being the original software.
+ * 3. This notice may not be removed or altered from any source distribution.
+ *
+ * Jean-loup Gailly Mark Adler
+ * jloup@gzip.org madler@alumni.caltech.edu
+ *
+ * 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);
+}
+
+/* TODO(cavalcanti): see crbug.com/1110083. */
+static inline unsigned char FAR* chunkcopy_safe_ugly(unsigned char FAR* out,
+ unsigned dist,
+ unsigned len,
+ unsigned char FAR* limit) {
+#if defined(__GNUC__) && !defined(__clang__)
+ /* Speed is the same as using chunkcopy_safe
+ w/ GCC on ARM (tested gcc 6.3 and 7.5) and avoids
+ undefined behavior.
+ */
+ return chunkcopy_core_safe(out, out - dist, len, limit);
+#elif defined(__clang__) && !defined(__aarch64__)
+ /* Seems to perform better on 32bit (i.e. Android). */
+ return chunkcopy_core_safe(out, out - dist, len, limit);
+#else
+ /* Seems to perform better on 64-bit. */
+ return chunkcopy_lapped_safe(out, dist, len, limit);
+#endif
+}
+
+/*
+ * 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 */