/src/libdeflate/common_defs.h

Source
/*
 * common_defs.h
 *
 * Copyright 2016 Eric Biggers
 *
 * 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.
 */

#ifndef COMMON_DEFS_H
#define COMMON_DEFS_H

#include "libdeflate.h"

#include <stdbool.h>
#include <stddef.h> /* for size_t */
#include <stdint.h>
#ifdef _MSC_VER
#  include <intrin.h> /* for _BitScan*() and other intrinsics */
#  include <stdlib.h> /* for _byteswap_*() */
   /* Disable MSVC warnings that are expected. */
   /* /W2 */
#  pragma warning(disable : 4146) /* unary minus on unsigned type */
   /* /W3 */
#  pragma warning(disable : 4018) /* signed/unsigned mismatch */
#  pragma warning(disable : 4244) /* possible loss of data */
#  pragma warning(disable : 4267) /* possible loss of precision */
#  pragma warning(disable : 4310) /* cast truncates constant value */
   /* /W4 */
#  pragma warning(disable : 4100) /* unreferenced formal parameter */
#  pragma warning(disable : 4127) /* conditional expression is constant */
#  pragma warning(disable : 4189) /* local variable initialized but not referenced */
#  pragma warning(disable : 4232) /* nonstandard extension used */
#  pragma warning(disable : 4245) /* conversion from 'int' to 'unsigned int' */
#  pragma warning(disable : 4295) /* array too small to include terminating null */
#endif
#ifndef FREESTANDING
#  include <string.h> /* for memcpy() */
#endif

/* ========================================================================== */
/*                             Target architecture                            */
/* ========================================================================== */

/* If possible, define a compiler-independent ARCH_* macro. */
#undef ARCH_X86_64
#undef ARCH_X86_32
#undef ARCH_ARM64
#undef ARCH_ARM32
#undef ARCH_RISCV
#ifdef _MSC_VER
   /* Way too many things are broken in ARM64EC to pretend that it is x86_64. */
#  if defined(_M_X64) && !defined(_M_ARM64EC)
#    define ARCH_X86_64
#  elif defined(_M_IX86)
#    define ARCH_X86_32
#  elif defined(_M_ARM64)
#    define ARCH_ARM64
#  elif defined(_M_ARM)
#    define ARCH_ARM32
#  endif
#else
#  if defined(__x86_64__)
#    define ARCH_X86_64
#  elif defined(__i386__)
#    define ARCH_X86_32
#  elif defined(__aarch64__)
#    define ARCH_ARM64
#  elif defined(__arm__)
#    define ARCH_ARM32
#  elif defined(__riscv)
#    define ARCH_RISCV
#  endif
#endif

/* ========================================================================== */
/*                              Type definitions                              */
/* ========================================================================== */

/* Fixed-width integer types */
typedef uint8_t u8;
typedef uint16_t u16;
typedef uint32_t u32;
typedef uint64_t u64;
typedef int8_t s8;
typedef int16_t s16;
typedef int32_t s32;
typedef int64_t s64;

/* ssize_t, if not available in <sys/types.h> */
#ifdef _MSC_VER
#  ifdef _WIN64
     typedef long long ssize_t;
#  else
     typedef long ssize_t;
#  endif
#endif

/*
 * Word type of the target architecture.  Use 'size_t' instead of
 * 'unsigned long' to account for platforms such as Windows that use 32-bit
 * 'unsigned long' on 64-bit architectures.
 */
typedef size_t machine_word_t;

/* Number of bytes in a word */
#define WORDBYTES ((int)sizeof(machine_word_t))

/* Number of bits in a word */
#define WORDBITS  (8 * WORDBYTES)

/* ========================================================================== */
/*                         Optional compiler features                         */
/* ========================================================================== */

/* Compiler version checks.  Only use when absolutely necessary. */
#if defined(__GNUC__) && !defined(__clang__) && !defined(__INTEL_COMPILER)
#  define GCC_PREREQ(major, minor)    \
  (__GNUC__ > (major) ||      \
   (__GNUC__ == (major) && __GNUC_MINOR__ >= (minor)))
#  if !GCC_PREREQ(4, 9)
#    error "gcc versions older than 4.9 are no longer supported"
#  endif
#else
#  define GCC_PREREQ(major, minor)  0
#endif
#ifdef __clang__
#  ifdef __apple_build_version__
#    define CLANG_PREREQ(major, minor, apple_version) \
  (__apple_build_version__ >= (apple_version))
#  else
#    define CLANG_PREREQ(major, minor, apple_version) \
  (__clang_major__ > (major) ||     \
   (__clang_major__ == (major) && __clang_minor__ >= (minor)))
#  endif
#  if !CLANG_PREREQ(3, 9, 8000000)
#    error "clang versions older than 3.9 are no longer supported"
#  endif
#else
#  define CLANG_PREREQ(major, minor, apple_version) 0
#endif
#ifdef _MSC_VER
#  define MSVC_PREREQ(version)  (_MSC_VER >= (version))
#  if !MSVC_PREREQ(1900)
#    error "MSVC versions older than Visual Studio 2015 are no longer supported"
#  endif
#else
#  define MSVC_PREREQ(version)  0
#endif

/*
 * __has_attribute(attribute) - check whether the compiler supports the given
 * attribute (and also supports doing the check in the first place).  Mostly
 * useful just for clang, since gcc didn't add this macro until gcc 5.
 */
#ifndef __has_attribute
#  define __has_attribute(attribute)  0
#endif

/*
 * __has_builtin(builtin) - check whether the compiler supports the given
 * builtin (and also supports doing the check in the first place).  Mostly
 * useful just for clang, since gcc didn't add this macro until gcc 10.
 */
#ifndef __has_builtin
#  define __has_builtin(builtin)  0
#endif

/* inline - suggest that a function be inlined */
#ifdef _MSC_VER
#  define inline    __inline
#endif /* else assume 'inline' is usable as-is */

/* forceinline - force a function to be inlined, if possible */
#if defined(__GNUC__) || __has_attribute(always_inline)
#  define forceinline   inline __attribute__((always_inline))
#elif defined(_MSC_VER)
#  define forceinline   __forceinline
#else
#  define forceinline   inline
#endif

/* MAYBE_UNUSED - mark a function or variable as maybe unused */
#if defined(__GNUC__) || __has_attribute(unused)
#  define MAYBE_UNUSED    __attribute__((unused))
#else
#  define MAYBE_UNUSED
#endif

/* NORETURN - mark a function as never returning, e.g. due to calling abort() */
#if defined(__GNUC__) || __has_attribute(noreturn)
#  define NORETURN    __attribute__((noreturn))
#else
#  define NORETURN
#endif

/*
 * restrict - hint that writes only occur through the given pointer.
 *
 * Don't use MSVC's __restrict, since it has nonstandard behavior.
 * Standard restrict is okay, if it is supported.
 */
#if !defined(__STDC_VERSION__) || (__STDC_VERSION__ < 201112L)
#  if defined(__GNUC__) || defined(__clang__)
#    define restrict    __restrict__
#  else
#    define restrict
#  endif
#endif /* else assume 'restrict' is usable as-is */

/* likely(expr) - hint that an expression is usually true */
#if defined(__GNUC__) || __has_builtin(__builtin_expect)
#  define likely(expr)    __builtin_expect(!!(expr), 1)
#else
#  define likely(expr)    (expr)
#endif

/* unlikely(expr) - hint that an expression is usually false */
#if defined(__GNUC__) || __has_builtin(__builtin_expect)
#  define unlikely(expr)  __builtin_expect(!!(expr), 0)
#else
#  define unlikely(expr)  (expr)
#endif

/* prefetchr(addr) - prefetch into L1 cache for read */
#undef prefetchr
#if defined(__GNUC__) || __has_builtin(__builtin_prefetch)
#  define prefetchr(addr) __builtin_prefetch((addr), 0)
#elif defined(_MSC_VER)
#  if defined(ARCH_X86_32) || defined(ARCH_X86_64)
#    define prefetchr(addr) _mm_prefetch((addr), _MM_HINT_T0)
#  elif defined(ARCH_ARM64)
#    define prefetchr(addr) __prefetch2((addr), 0x00 /* prfop=PLDL1KEEP */)
#  elif defined(ARCH_ARM32)
#    define prefetchr(addr) __prefetch(addr)
#  endif
#endif
#ifndef prefetchr
#  define prefetchr(addr)
#endif

/* prefetchw(addr) - prefetch into L1 cache for write */
#undef prefetchw
#if defined(__GNUC__) || __has_builtin(__builtin_prefetch)
#  define prefetchw(addr) __builtin_prefetch((addr), 1)
#elif defined(_MSC_VER)
#  if defined(ARCH_X86_32) || defined(ARCH_X86_64)
#    define prefetchw(addr) _m_prefetchw(addr)
#  elif defined(ARCH_ARM64)
#    define prefetchw(addr) __prefetch2((addr), 0x10 /* prfop=PSTL1KEEP */)
#  elif defined(ARCH_ARM32)
#    define prefetchw(addr) __prefetchw(addr)
#  endif
#endif
#ifndef prefetchw
#  define prefetchw(addr)
#endif

/*
 * _aligned_attribute(n) - declare that the annotated variable, or variables of
 * the annotated type, must be aligned on n-byte boundaries.
 */
#undef _aligned_attribute
#if defined(__GNUC__) || __has_attribute(aligned)
#  define _aligned_attribute(n) __attribute__((aligned(n)))
#elif defined(_MSC_VER)
#  define _aligned_attribute(n) __declspec(align(n))
#endif

/*
 * _target_attribute(attrs) - override the compilation target for a function.
 *
 * This accepts one or more comma-separated suffixes to the -m prefix jointly
 * forming the name of a machine-dependent option.  On gcc-like compilers, this
 * enables codegen for the given targets, including arbitrary compiler-generated
 * code as well as the corresponding intrinsics.  On other compilers this macro
 * expands to nothing, though MSVC allows intrinsics to be used anywhere anyway.
 */
#if defined(__GNUC__) || __has_attribute(target)
#  define _target_attribute(attrs)  __attribute__((target(attrs)))
#else
#  define _target_attribute(attrs)
#endif

/* ========================================================================== */
/*                          Miscellaneous macros                              */
/* ========================================================================== */

#define ARRAY_LEN(A)    (sizeof(A) / sizeof((A)[0]))
#define MIN(a, b)   ((a) <= (b) ? (a) : (b))
#define MAX(a, b)   ((a) >= (b) ? (a) : (b))
#define DIV_ROUND_UP(n, d)  (((n) + (d) - 1) / (d))
#define STATIC_ASSERT(expr) ((void)sizeof(char[1 - 2 * !(expr)]))
#define ALIGN(n, a)   (((n) + (a) - 1) & ~((a) - 1))
#define ROUND_UP(n, d)    ((d) * DIV_ROUND_UP((n), (d)))

/* ========================================================================== */
/*                           Endianness handling                              */
/* ========================================================================== */

/*
 * CPU_IS_LITTLE_ENDIAN() - 1 if the CPU is little endian, or 0 if it is big
 * endian.  When possible this is a compile-time macro that can be used in
 * preprocessor conditionals.  As a fallback, a generic method is used that
 * can't be used in preprocessor conditionals but should still be optimized out.
 */
#if defined(__BYTE_ORDER__) /* gcc v4.6+ and clang */
#  define CPU_IS_LITTLE_ENDIAN()  (__BYTE_ORDER__ == __ORDER_LITTLE_ENDIAN__)
#elif defined(_MSC_VER)
#  define CPU_IS_LITTLE_ENDIAN()  true
#else
static forceinline bool CPU_IS_LITTLE_ENDIAN(void)
{
  union {
    u32 w;
    u8 b;
  } u;

  u.w = 1;
  return u.b;
}
#endif

/* bswap16(v) - swap the bytes of a 16-bit integer */
static forceinline u16 bswap16(u16 v)
{
#if defined(__GNUC__) || __has_builtin(__builtin_bswap16)
  return __builtin_bswap16(v);
#elif defined(_MSC_VER)
  return _byteswap_ushort(v);
#else
  return (v << 8) | (v >> 8);
#endif
}

/* bswap32(v) - swap the bytes of a 32-bit integer */
static forceinline u32 bswap32(u32 v)
{
#if defined(__GNUC__) || __has_builtin(__builtin_bswap32)
  return __builtin_bswap32(v);
#elif defined(_MSC_VER)
  return _byteswap_ulong(v);
#else
  return ((v & 0x000000FF) << 24) |
         ((v & 0x0000FF00) << 8) |
         ((v & 0x00FF0000) >> 8) |
         ((v & 0xFF000000) >> 24);
#endif
}

/* bswap64(v) - swap the bytes of a 64-bit integer */
static forceinline u64 bswap64(u64 v)
{
#if defined(__GNUC__) || __has_builtin(__builtin_bswap64)
  return __builtin_bswap64(v);
#elif defined(_MSC_VER)
  return _byteswap_uint64(v);
#else
  return ((v & 0x00000000000000FF) << 56) |
         ((v & 0x000000000000FF00) << 40) |
         ((v & 0x0000000000FF0000) << 24) |
         ((v & 0x00000000FF000000) << 8) |
         ((v & 0x000000FF00000000) >> 8) |
         ((v & 0x0000FF0000000000) >> 24) |
         ((v & 0x00FF000000000000) >> 40) |
         ((v & 0xFF00000000000000) >> 56);
#endif
}

#define le16_bswap(v) (CPU_IS_LITTLE_ENDIAN() ? (v) : bswap16(v))
#define le32_bswap(v) (CPU_IS_LITTLE_ENDIAN() ? (v) : bswap32(v))
#define le64_bswap(v) (CPU_IS_LITTLE_ENDIAN() ? (v) : bswap64(v))
#define be16_bswap(v) (CPU_IS_LITTLE_ENDIAN() ? bswap16(v) : (v))
#define be32_bswap(v) (CPU_IS_LITTLE_ENDIAN() ? bswap32(v) : (v))
#define be64_bswap(v) (CPU_IS_LITTLE_ENDIAN() ? bswap64(v) : (v))

/* ========================================================================== */
/*                          Unaligned memory accesses                         */
/* ========================================================================== */

/*
 * UNALIGNED_ACCESS_IS_FAST() - 1 if unaligned memory accesses can be performed
 * efficiently on the target platform, otherwise 0.
 */
#if (defined(__GNUC__) || defined(__clang__)) && \
  (defined(ARCH_X86_64) || defined(ARCH_X86_32) || \
   defined(__ARM_FEATURE_UNALIGNED) || \
   defined(__powerpc64__) || defined(__powerpc__) || defined(__POWERPC__) || \
   defined(__riscv_misaligned_fast) || \
   /*
    * For all compilation purposes, WebAssembly behaves like any other CPU
    * instruction set. Even though WebAssembly engine might be running on
    * top of different actual CPU architectures, the WebAssembly spec
    * itself permits unaligned access and it will be fast on most of those
    * platforms, and simulated at the engine level on others, so it's
    * worth treating it as a CPU architecture with fast unaligned access.
    */ defined(__wasm__))
#  define UNALIGNED_ACCESS_IS_FAST  1
#elif defined(_MSC_VER)
#  define UNALIGNED_ACCESS_IS_FAST  1
#else
#  define UNALIGNED_ACCESS_IS_FAST  0
#endif

/*
 * Implementing unaligned memory accesses using memcpy() is portable, and it
 * usually gets optimized appropriately by modern compilers.  I.e., each
 * memcpy() of 1, 2, 4, or WORDBYTES bytes gets compiled to a load or store
 * instruction, not to an actual function call.
 *
 * We no longer use the "packed struct" approach to unaligned accesses, as that
 * is nonstandard, has unclear semantics, and doesn't receive enough testing
 * (see https://gcc.gnu.org/bugzilla/show_bug.cgi?id=94994).
 *
 * arm32 with __ARM_FEATURE_UNALIGNED in gcc 5 and earlier is a known exception
 * where memcpy() generates inefficient code
 * (https://gcc.gnu.org/bugzilla/show_bug.cgi?id=67366).  However, we no longer
 * consider that one case important enough to maintain different code for.
 * If you run into it, please just use a newer version of gcc (or use clang).
 */

#ifdef FREESTANDING
#  define MEMCOPY __builtin_memcpy
#else
#  define MEMCOPY memcpy
#endif

/* Unaligned loads and stores without endianness conversion */

#define DEFINE_UNALIGNED_TYPE(type)       \
static forceinline type           \
load_##type##_unaligned(const void *p)        \
{               \
  type v;             \
                \
  MEMCOPY(&v, p, sizeof(v));       \
  return v;           \
}                \
                \
static forceinline void           \
store_##type##_unaligned(type v, void *p)     \
{               \
  MEMCOPY(p, &v, sizeof(v));       \
}

DEFINE_UNALIGNED_TYPE(u16)
DEFINE_UNALIGNED_TYPE(u32)
DEFINE_UNALIGNED_TYPE(u64)
DEFINE_UNALIGNED_TYPE(machine_word_t)

#undef MEMCOPY

#define load_word_unaligned load_machine_word_t_unaligned
#define store_word_unaligned  store_machine_word_t_unaligned

/* Unaligned loads with endianness conversion */

static forceinline u16
get_unaligned_le16(const u8 *p)
{
  if (UNALIGNED_ACCESS_IS_FAST)
    return le16_bswap(load_u16_unaligned(p));
  else
    return ((u16)p[1] << 8) | p[0];
}

static forceinline u16
get_unaligned_be16(const u8 *p)
{
  if (UNALIGNED_ACCESS_IS_FAST)
    return be16_bswap(load_u16_unaligned(p));
  else
    return ((u16)p[0] << 8) | p[1];
}

static forceinline u32
get_unaligned_le32(const u8 *p)
{
  if (UNALIGNED_ACCESS_IS_FAST)
    return le32_bswap(load_u32_unaligned(p));
  else
    return ((u32)p[3] << 24) | ((u32)p[2] << 16) |
      ((u32)p[1] << 8) | p[0];
}

static forceinline u32
get_unaligned_be32(const u8 *p)
{
  if (UNALIGNED_ACCESS_IS_FAST)
    return be32_bswap(load_u32_unaligned(p));
  else
    return ((u32)p[0] << 24) | ((u32)p[1] << 16) |
      ((u32)p[2] << 8) | p[3];
}

static forceinline u64
get_unaligned_le64(const u8 *p)
{
  if (UNALIGNED_ACCESS_IS_FAST)
    return le64_bswap(load_u64_unaligned(p));
  else
    return ((u64)p[7] << 56) | ((u64)p[6] << 48) |
      ((u64)p[5] << 40) | ((u64)p[4] << 32) |
      ((u64)p[3] << 24) | ((u64)p[2] << 16) |
      ((u64)p[1] << 8) | p[0];
}

static forceinline machine_word_t
get_unaligned_leword(const u8 *p)
{
  STATIC_ASSERT(WORDBITS == 32 || WORDBITS == 64);
  if (WORDBITS == 32)
    return get_unaligned_le32(p);
  else
    return get_unaligned_le64(p);
}

/* Unaligned stores with endianness conversion */

static forceinline void
put_unaligned_le16(u16 v, u8 *p)
{
  if (UNALIGNED_ACCESS_IS_FAST) {
    store_u16_unaligned(le16_bswap(v), p);
  } else {
    p[0] = (u8)(v >> 0);
    p[1] = (u8)(v >> 8);
  }
}

static forceinline void
put_unaligned_be16(u16 v, u8 *p)
{
  if (UNALIGNED_ACCESS_IS_FAST) {
    store_u16_unaligned(be16_bswap(v), p);
  } else {
    p[0] = (u8)(v >> 8);
    p[1] = (u8)(v >> 0);
  }
}

static forceinline void
put_unaligned_le32(u32 v, u8 *p)
{
  if (UNALIGNED_ACCESS_IS_FAST) {
    store_u32_unaligned(le32_bswap(v), p);
  } else {
    p[0] = (u8)(v >> 0);
    p[1] = (u8)(v >> 8);
    p[2] = (u8)(v >> 16);
    p[3] = (u8)(v >> 24);
  }
}

static forceinline void
put_unaligned_be32(u32 v, u8 *p)
{
  if (UNALIGNED_ACCESS_IS_FAST) {
    store_u32_unaligned(be32_bswap(v), p);
  } else {
    p[0] = (u8)(v >> 24);
    p[1] = (u8)(v >> 16);
    p[2] = (u8)(v >> 8);
    p[3] = (u8)(v >> 0);
  }
}

static forceinline void
put_unaligned_le64(u64 v, u8 *p)
{
  if (UNALIGNED_ACCESS_IS_FAST) {
    store_u64_unaligned(le64_bswap(v), p);
  } else {
    p[0] = (u8)(v >> 0);
    p[1] = (u8)(v >> 8);
    p[2] = (u8)(v >> 16);
    p[3] = (u8)(v >> 24);
    p[4] = (u8)(v >> 32);
    p[5] = (u8)(v >> 40);
    p[6] = (u8)(v >> 48);
    p[7] = (u8)(v >> 56);
  }
}

static forceinline void
put_unaligned_leword(machine_word_t v, u8 *p)
{
  STATIC_ASSERT(WORDBITS == 32 || WORDBITS == 64);
  if (WORDBITS == 32)
    put_unaligned_le32(v, p);
  else
    put_unaligned_le64(v, p);
}

/* ========================================================================== */
/*                         Bit manipulation functions                         */
/* ========================================================================== */

/*
 * Bit Scan Reverse (BSR) - find the 0-based index (relative to the least
 * significant end) of the *most* significant 1 bit in the input value.  The
 * input value must be nonzero!
 */

static forceinline unsigned
bsr32(u32 v)
{
#if defined(__GNUC__) || __has_builtin(__builtin_clz)
  return 31 - __builtin_clz(v);
#elif defined(_MSC_VER)
  unsigned long i;

  _BitScanReverse(&i, v);
  return i;
#else
  unsigned i = 0;

  while ((v >>= 1) != 0)
    i++;
  return i;
#endif
}

static forceinline unsigned
bsr64(u64 v)
{
#if defined(__GNUC__) || __has_builtin(__builtin_clzll)
  return 63 - __builtin_clzll(v);
#elif defined(_MSC_VER) && defined(_WIN64)
  unsigned long i;

  _BitScanReverse64(&i, v);
  return i;
#else
  unsigned i = 0;

  while ((v >>= 1) != 0)
    i++;
  return i;
#endif
}

static forceinline unsigned
bsrw(machine_word_t v)
{
  STATIC_ASSERT(WORDBITS == 32 || WORDBITS == 64);
  if (WORDBITS == 32)
    return bsr32(v);
  else
    return bsr64(v);
}

/*
 * Bit Scan Forward (BSF) - find the 0-based index (relative to the least
 * significant end) of the *least* significant 1 bit in the input value.  The
 * input value must be nonzero!
 */

static forceinline unsigned
bsf32(u32 v)
{
#if defined(__GNUC__) || __has_builtin(__builtin_ctz)
  return __builtin_ctz(v);
#elif defined(_MSC_VER)
  unsigned long i;

  _BitScanForward(&i, v);
  return i;
#else
  unsigned i = 0;

  for (; (v & 1) == 0; v >>= 1)
    i++;
  return i;
#endif
}

static forceinline unsigned
bsf64(u64 v)
{
#if defined(__GNUC__) || __has_builtin(__builtin_ctzll)
  return __builtin_ctzll(v);
#elif defined(_MSC_VER) && defined(_WIN64)
  unsigned long i;

  _BitScanForward64(&i, v);
  return i;
#else
  unsigned i = 0;

  for (; (v & 1) == 0; v >>= 1)
    i++;
  return i;
#endif
}

static forceinline unsigned
bsfw(machine_word_t v)
{
  STATIC_ASSERT(WORDBITS == 32 || WORDBITS == 64);
  if (WORDBITS == 32)
    return bsf32(v);
  else
    return bsf64(v);
}

/*
 * rbit32(v): reverse the bits in a 32-bit integer.  This doesn't have a
 * fallback implementation; use '#ifdef rbit32' to check if this is available.
 */
#undef rbit32
#if (defined(__GNUC__) || defined(__clang__)) && defined(ARCH_ARM32) && \
  (__ARM_ARCH >= 7 || (__ARM_ARCH == 6 && defined(__ARM_ARCH_6T2__)))
static forceinline u32
rbit32(u32 v)
{
  __asm__("rbit %0, %1" : "=r" (v) : "r" (v));
  return v;
}
#define rbit32 rbit32
#elif (defined(__GNUC__) || defined(__clang__)) && defined(ARCH_ARM64)
static forceinline u32
rbit32(u32 v)
{
  __asm__("rbit %w0, %w1" : "=r" (v) : "r" (v));
  return v;
}
#define rbit32 rbit32
#endif

#endif /* COMMON_DEFS_H */

Coverage Report

Created: 2026-03-31 06:56