Initial import

libc/log/bisectsymbol.c

@@ -0,0 +1,43 @@
+/*-*- mode:c;indent-tabs-mode:nil;c-basic-offset:2;tab-width:8;coding:utf-8 -*-│
+│vi: set net ft=c ts=2 sts=2 sw=2 fenc=utf-8                                :vi│
+╞══════════════════════════════════════════════════════════════════════════════╡
+│ Copyright 2020 Justine Alexandra Roberts Tunney                              │
+│                                                                              │
+│ This program is free software; you can redistribute it and/or modify         │
+│ it under the terms of the GNU General Public License as published by         │
+│ the Free Software Foundation; version 2 of the License.                      │
+│                                                                              │
+│ This program is distributed in the hope that it will be useful, but          │
+│ WITHOUT ANY WARRANTY; without even the implied warranty of                   │
+│ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU             │
+│ General Public License for more details.                                     │
+│                                                                              │
+│ You should have received a copy of the GNU General Public License            │
+│ along with this program; if not, write to the Free Software                  │
+│ Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA                │
+│ 02110-1301 USA                                                               │
+╚─────────────────────────────────────────────────────────────────────────────*/
+#include "libc/alg/bisectcarleft.h"
+#include "libc/assert.h"
+#include "libc/runtime/symbols.h"
+
+/**
+ * Finds symbol associated with address.
+ * @param symbol table pointer (null propagating)
+ * @return symbol address or NULL if not found
+ */
+const struct Symbol *bisectsymbol(struct SymbolTable *t,
+                                  intptr_t virtual_address,
+                                  int64_t *opt_out_addend) {
+  const struct Symbol *symbol = NULL;
+  int64_t addend = (intptr_t)virtual_address;
+  if (t && t->count) {
+    unsigned key = (unsigned)((intptr_t)virtual_address - t->addr_base - 1);
+    unsigned i = bisectcarleft((const int32_t(*)[2])t->symbols, t->count, key);
+    assert(0 <= i && i < t->count);
+    symbol = &t->symbols[i];
+    addend = (int64_t)key - (int64_t)symbol->addr_rva;
+  }
+  if (opt_out_addend) *opt_out_addend = addend;
+  return symbol;
+}