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-rw-r--r--src/x86_64/tsc-x86_64.s40
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diff --git a/src/x86_64/tsc-x86_64.s b/src/x86_64/tsc-x86_64.s
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+/*************************************************************************
+ * Copyright (C) 2008 Tavian Barnes <tavianator@gmail.com> *
+ * *
+ * This file is part of The Sandglass Library. *
+ * *
+ * The Sandglass Library is free software; you can redistribute it *
+ * and/or modify it under the terms of the GNU Lesser General Public *
+ * License as published by the Free Software Foundation; either version *
+ * 3 of the License, or (at your option) any later version. *
+ * *
+ * The Sandglass Library 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 *
+ * Lesser General Public License for more details. *
+ * *
+ * You should have received a copy of the GNU Lesser General Public *
+ * License along with this program. If not, see *
+ * <http://www.gnu.org/licenses/>. *
+ *************************************************************************/
+
+/*
+ * Return the time stamp counter, and serialize the instruction
+ */
+
+ .text
+/* long sandglass_get_tsc(); */
+.globl sandglass_get_tsc
+ .type sandglass_get_tsc, @function
+ticks:
+ movq %rbx, %rdi /* Callee-save register, clobbered by cpuid */
+ cpuid /* Serialize */
+ rdtsc /* Read time stamp counter */
+ shlq $32, %rdx
+ orq %rdx, %rax
+ movq %rax, %rsi
+ cpuid /* Serialize again */
+ movq %rsi, %rax
+ movq %rdi, %rbx
+ ret
+ .size sandglass_get_tsc, .-sandglass_get_tsc