Add BIT64 methods for dealing with bitmaps

64 bit is the norm, so 64 bits are the best natural scalar for this.

Signed-off-by: Pantelis Antoniou <[email protected]>

src/Makefile.am

@@ -36,7 +36,8 @@ libfyaml_la_SOURCES = \
 	util/fy-endian.h \
 	util/fy-blob.c util/fy-blob.h \
 	util/fy-id.h \
-	util/fy-align.h
+	util/fy-align.h \
+	util/fy-bit64.h
 
 libfyaml_la_CPPFLAGS = $(AM_CPPFLAGS) \
 		       -I$(top_srcdir)/src/lib \

src/util/fy-bit64.h

@@ -0,0 +1,86 @@
+/*
+ * fy-bit64.h - various bit64 methods
+ *
+ * Copyright (c) 2023 Pantelis Antoniou <[email protected]>
+ *
+ * SPDX-License-Identifier: MIT
+ */
+
+#ifndef FY_BIT64_H
+#define FY_BIT64_H
+
+#ifdef HAVE_CONFIG_H
+#include "config.h"
+#endif
+
+#include <stdint.h>
+
+#define FY_BIT64(x) ((uint64_t)1 << (x))
+#define FY_BIT64_COUNT(_x) (((_x) + 63) / 64)
+#define FY_BIT64_SIZE(_x) ((size_t)((((_x) + 63) / 64) * sizeof(uint64_t)))
+
+#if (defined(__GNUC__) && __GNUC__ >= 4) || defined(__clang__)
+
+#define FY_BIT64_LOWEST(_x) ((unsigned int)__builtin_ctzll((unsigned long long)(_x)))
+#define FY_BIT64_HIGHEST(_x) ((unsigned int)__builtin_clzll((unsigned long long)(_x)))
+#define FY_BIT64_POPCNT(_x) ((unsigned int)__builtin_popcountl((unsigned long long)(_x)))
+
+static inline unsigned int fy_bit64_lowest(uint64_t x)
+{
+	return FY_BIT64_LOWEST(x);
+}
+
+static inline unsigned int fy_bit64_highest(uint64_t x)
+{
+	return FY_BIT64_HIGHEST(x);
+}
+
+static inline unsigned int FY_bit64_popcnt(uint64_t x)
+{
+	return FY_BIT64_POPCNT(x);
+}
+
+#else	/* portable implementation */
+
+static inline unsigned int FY_BIT64_LOWEST(uint64_t x)
+{
+	unsigned int c = 0;
+
+	if (!(x & 0x00000000ffffffffULL)) { x >>= 32; c += 32; }
+	if (!(x & 0x000000000000ffffULL)) { x >>= 16; c += 16; }
+	if (!(x & 0x00000000000000ffULL)) { x >>=  8; c +=  8; }
+	if (!(x & 0x000000000000000fULL)) { x >>=  4; c +=  4; }
+	if (!(x & 0x0000000000000003ULL)) { x >>=  2; c +=  2; }
+	if (!(x & 0x0000000000000001ULL)) {           c +=  1; }
+	return c;
+}
+
+static inline unsigned int FY_BIT64_HIGHEST(uint64_t x)
+{
+	unsigned int c = 0;
+
+	if (x & 0xffffffff00000000ULL) { x >>= 32; c += 32; }
+	if (x & 0x00000000ffff0000ULL) { x >>= 16; c += 16; }
+	if (x & 0x000000000000ff00ULL) { x >>=  8; c +=  8; }
+	if (x & 0x00000000000000f0ULL) { x >>=  4; c +=  4; }
+	if (x & 0x000000000000000cULL) { x >>=  2; c +=  2; }
+	if (x & 0x0000000000000002ULL) {           c +=  1; }
+	return c;
+}
+
+static inline unsigned int FY_BIT64_POPCNT(uint64_t x)
+{
+	unsigned int count;
+
+	for (count = 0; x; x &= x - 1)
+		count++;
+	return count;
+}
+
+#define FY_BIT64_LOWEST(_x) fy_bit64_lowest(_x)
+#define FY_BIT64_HIGEST(_x) fy_bit64_highest(_x)
+#define FY_BIT64_POPCNT(_x) fy_bit64_popcnt(_x)
+
+#endif
+
+#endif