Squashed 'third_party/git/' content from commit cb71568594

git-subtree-dir: third_party/git
git-subtree-split: cb715685942260375e1eb8153b0768a376e4ece7

1 files changed, 217 insertions, 0 deletions

diff --git a/compat/bswap.h b/compat/bswap.h
new file mode 100644
index 000000000000..e4e25735ceb3
--- /dev/null
+++ b/compat/bswap.h
@@ -0,0 +1,217 @@
+#ifndef COMPAT_BSWAP_H
+#define COMPAT_BSWAP_H
+
+/*
+ * Let's make sure we always have a sane definition for ntohl()/htonl().
+ * Some libraries define those as a function call, just to perform byte
+ * shifting, bringing significant overhead to what should be a simple
+ * operation.
+ */
+
+/*
+ * Default version that the compiler ought to optimize properly with
+ * constant values.
+ */
+static inline uint32_t default_swab32(uint32_t val)
+{
+	return (((val & 0xff000000) >> 24) |
+		((val & 0x00ff0000) >>  8) |
+		((val & 0x0000ff00) <<  8) |
+		((val & 0x000000ff) << 24));
+}
+
+static inline uint64_t default_bswap64(uint64_t val)
+{
+	return (((val & (uint64_t)0x00000000000000ffULL) << 56) |
+		((val & (uint64_t)0x000000000000ff00ULL) << 40) |
+		((val & (uint64_t)0x0000000000ff0000ULL) << 24) |
+		((val & (uint64_t)0x00000000ff000000ULL) <<  8) |
+		((val & (uint64_t)0x000000ff00000000ULL) >>  8) |
+		((val & (uint64_t)0x0000ff0000000000ULL) >> 24) |
+		((val & (uint64_t)0x00ff000000000000ULL) >> 40) |
+		((val & (uint64_t)0xff00000000000000ULL) >> 56));
+}
+
+#undef bswap32
+#undef bswap64
+
+#if defined(__GNUC__) && (defined(__i386__) || defined(__x86_64__))
+
+#define bswap32 git_bswap32
+static inline uint32_t git_bswap32(uint32_t x)
+{
+	uint32_t result;
+	if (__builtin_constant_p(x))
+		result = default_swab32(x);
+	else
+		__asm__("bswap %0" : "=r" (result) : "0" (x));
+	return result;
+}
+
+#define bswap64 git_bswap64
+#if defined(__x86_64__)
+static inline uint64_t git_bswap64(uint64_t x)
+{
+	uint64_t result;
+	if (__builtin_constant_p(x))
+		result = default_bswap64(x);
+	else
+		__asm__("bswap %q0" : "=r" (result) : "0" (x));
+	return result;
+}
+#else
+static inline uint64_t git_bswap64(uint64_t x)
+{
+	union { uint64_t i64; uint32_t i32[2]; } tmp, result;
+	if (__builtin_constant_p(x))
+		result.i64 = default_bswap64(x);
+	else {
+		tmp.i64 = x;
+		result.i32[0] = git_bswap32(tmp.i32[1]);
+		result.i32[1] = git_bswap32(tmp.i32[0]);
+	}
+	return result.i64;
+}
+#endif
+
+#elif defined(_MSC_VER) && (defined(_M_IX86) || defined(_M_X64))
+
+#include <stdlib.h>
+
+#define bswap32(x) _byteswap_ulong(x)
+#define bswap64(x) _byteswap_uint64(x)
+
+#endif
+
+#if defined(bswap32)
+
+#undef ntohl
+#undef htonl
+#define ntohl(x) bswap32(x)
+#define htonl(x) bswap32(x)
+
+#endif
+
+#if defined(bswap64)
+
+#undef ntohll
+#undef htonll
+#define ntohll(x) bswap64(x)
+#define htonll(x) bswap64(x)
+
+#else
+
+#undef ntohll
+#undef htonll
+
+#if defined(__BYTE_ORDER) && defined(__LITTLE_ENDIAN) && defined(__BIG_ENDIAN)
+
+# define GIT_BYTE_ORDER __BYTE_ORDER
+# define GIT_LITTLE_ENDIAN __LITTLE_ENDIAN
+# define GIT_BIG_ENDIAN __BIG_ENDIAN
+
+#elif defined(BYTE_ORDER) && defined(LITTLE_ENDIAN) && defined(BIG_ENDIAN)
+
+# define GIT_BYTE_ORDER BYTE_ORDER
+# define GIT_LITTLE_ENDIAN LITTLE_ENDIAN
+# define GIT_BIG_ENDIAN BIG_ENDIAN
+
+#else
+
+# define GIT_BIG_ENDIAN 4321
+# define GIT_LITTLE_ENDIAN 1234
+
+# if defined(_BIG_ENDIAN) && !defined(_LITTLE_ENDIAN)
+#  define GIT_BYTE_ORDER GIT_BIG_ENDIAN
+# elif defined(_LITTLE_ENDIAN) && !defined(_BIG_ENDIAN)
+#  define GIT_BYTE_ORDER GIT_LITTLE_ENDIAN
+# elif defined(__THW_BIG_ENDIAN__) && !defined(__THW_LITTLE_ENDIAN__)
+#  define GIT_BYTE_ORDER GIT_BIG_ENDIAN
+# elif defined(__THW_LITTLE_ENDIAN__) && !defined(__THW_BIG_ENDIAN__)
+#  define GIT_BYTE_ORDER GIT_LITTLE_ENDIAN
+# else
+#  error "Cannot determine endianness"
+# endif
+
+#endif
+
+#if GIT_BYTE_ORDER == GIT_BIG_ENDIAN
+# define ntohll(n) (n)
+# define htonll(n) (n)
+#else
+# define ntohll(n) default_bswap64(n)
+# define htonll(n) default_bswap64(n)
+#endif
+
+#endif
+
+/*
+ * Performance might be improved if the CPU architecture is OK with
+ * unaligned 32-bit loads and a fast ntohl() is available.
+ * Otherwise fall back to byte loads and shifts which is portable,
+ * and is faster on architectures with memory alignment issues.
+ */
+
+#if !defined(NO_UNALIGNED_LOADS) && ( \
+    defined(__i386__) || defined(__x86_64__) || \
+    defined(_M_IX86) || defined(_M_X64) || \
+    defined(__ppc__) || defined(__ppc64__) || \
+    defined(__powerpc__) || defined(__powerpc64__) || \
+    defined(__s390__) || defined(__s390x__))
+
+#define get_be16(p)	ntohs(*(unsigned short *)(p))
+#define get_be32(p)	ntohl(*(unsigned int *)(p))
+#define get_be64(p)	ntohll(*(uint64_t *)(p))
+#define put_be32(p, v)	do { *(unsigned int *)(p) = htonl(v); } while (0)
+#define put_be64(p, v)	do { *(uint64_t *)(p) = htonll(v); } while (0)
+
+#else
+
+static inline uint16_t get_be16(const void *ptr)
+{
+	const unsigned char *p = ptr;
+	return	(uint16_t)p[0] << 8 |
+		(uint16_t)p[1] << 0;
+}
+
+static inline uint32_t get_be32(const void *ptr)
+{
+	const unsigned char *p = ptr;
+	return	(uint32_t)p[0] << 24 |
+		(uint32_t)p[1] << 16 |
+		(uint32_t)p[2] <<  8 |
+		(uint32_t)p[3] <<  0;
+}
+
+static inline uint64_t get_be64(const void *ptr)
+{
+	const unsigned char *p = ptr;
+	return	(uint64_t)get_be32(&p[0]) << 32 |
+		(uint64_t)get_be32(&p[4]) <<  0;
+}
+
+static inline void put_be32(void *ptr, uint32_t value)
+{
+	unsigned char *p = ptr;
+	p[0] = value >> 24;
+	p[1] = value >> 16;
+	p[2] = value >>  8;
+	p[3] = value >>  0;
+}
+
+static inline void put_be64(void *ptr, uint64_t value)
+{
+	unsigned char *p = ptr;
+	p[0] = value >> 56;
+	p[1] = value >> 48;
+	p[2] = value >> 40;
+	p[3] = value >> 32;
+	p[4] = value >> 24;
+	p[5] = value >> 16;
+	p[6] = value >>  8;
+	p[7] = value >>  0;
+}
+
+#endif
+
+#endif /* COMPAT_BSWAP_H */