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authorDaniel Baumann <daniel.baumann@progress-linux.org>2024-04-19 02:57:58 +0000
committerDaniel Baumann <daniel.baumann@progress-linux.org>2024-04-19 02:57:58 +0000
commitbe1c7e50e1e8809ea56f2c9d472eccd8ffd73a97 (patch)
tree9754ff1ca740f6346cf8483ec915d4054bc5da2d /fluent-bit/lib/jemalloc-5.3.0/include/jemalloc/internal/div.h
parentInitial commit. (diff)
downloadnetdata-be1c7e50e1e8809ea56f2c9d472eccd8ffd73a97.tar.xz
netdata-be1c7e50e1e8809ea56f2c9d472eccd8ffd73a97.zip
Adding upstream version 1.44.3.upstream/1.44.3upstream
Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>
Diffstat (limited to 'fluent-bit/lib/jemalloc-5.3.0/include/jemalloc/internal/div.h')
-rw-r--r--fluent-bit/lib/jemalloc-5.3.0/include/jemalloc/internal/div.h41
1 files changed, 41 insertions, 0 deletions
diff --git a/fluent-bit/lib/jemalloc-5.3.0/include/jemalloc/internal/div.h b/fluent-bit/lib/jemalloc-5.3.0/include/jemalloc/internal/div.h
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+++ b/fluent-bit/lib/jemalloc-5.3.0/include/jemalloc/internal/div.h
@@ -0,0 +1,41 @@
+#ifndef JEMALLOC_INTERNAL_DIV_H
+#define JEMALLOC_INTERNAL_DIV_H
+
+#include "jemalloc/internal/assert.h"
+
+/*
+ * This module does the division that computes the index of a region in a slab,
+ * given its offset relative to the base.
+ * That is, given a divisor d, an n = i * d (all integers), we'll return i.
+ * We do some pre-computation to do this more quickly than a CPU division
+ * instruction.
+ * We bound n < 2^32, and don't support dividing by one.
+ */
+
+typedef struct div_info_s div_info_t;
+struct div_info_s {
+ uint32_t magic;
+#ifdef JEMALLOC_DEBUG
+ size_t d;
+#endif
+};
+
+void div_init(div_info_t *div_info, size_t divisor);
+
+static inline size_t
+div_compute(div_info_t *div_info, size_t n) {
+ assert(n <= (uint32_t)-1);
+ /*
+ * This generates, e.g. mov; imul; shr on x86-64. On a 32-bit machine,
+ * the compilers I tried were all smart enough to turn this into the
+ * appropriate "get the high 32 bits of the result of a multiply" (e.g.
+ * mul; mov edx eax; on x86, umull on arm, etc.).
+ */
+ size_t i = ((uint64_t)n * (uint64_t)div_info->magic) >> 32;
+#ifdef JEMALLOC_DEBUG
+ assert(i * div_info->d == n);
+#endif
+ return i;
+}
+
+#endif /* JEMALLOC_INTERNAL_DIV_H */