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arch/x86: remove arch-specific ffs.h, rely on compiler built-ins

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The compiler is going to make better per-arch/per-implementation
choices about bit operations, so let's use the common definitions.

Signed-off-by: Charles E. Youse <charles.youse@intel.com>
This commit is contained in:
Charles E. Youse 2019-06-27 15:59:43 -07:00 • committed by Anas Nashif
commit a039bec3c7
2 changed files with 1 additions and 135 deletions
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134
include/arch/x86/ffs.h
View file

@ -1,134 +0,0 @@
/*
* Copyright (c) 2014 Wind River Systems, Inc.
*
* SPDX-License-Identifier: Apache-2.0
*/
/**
* @file
* @brief X86 find-first-set interface
*
* X86-specific kernel ffs interface
*/
#ifndef ZEPHYR_INCLUDE_ARCH_X86_FFS_H_
#define ZEPHYR_INCLUDE_ARCH_X86_FFS_H_
#ifdef __cplusplus
extern "C" {
#endif
#ifndef _ASMLANGUAGE
#include <zephyr/types.h>
/**
*
* @brief find least significant bit set in a 32-bit word
*
* This routine finds the first bit set starting from the least significant bit
* in the argument passed in and returns the index of that bit. Bits are
* numbered starting at 1 from the least significant bit. A return value of
* zero indicates that the value passed is zero.
*
* @return least significant bit set, 0 if @a op is 0
*
* @internal
* For Intel64 (x86_64) architectures, the 'cmovzl' can be removed and leverage
* the fact that the 'bsfl' doesn't modify the destination operand when the
* source operand is zero. The "bitpos" variable can be preloaded into the
* destination register, and given the unconditional ++bitpos that is performed
* after the 'cmovzl', the correct results are yielded.
*/
static ALWAYS_INLINE unsigned int find_lsb_set(u32_t op)
{
unsigned int bitpos;
__asm__ volatile (
#ifdef CONFIG_CPU_MINUTEIA
/* Minute IA doesn't support cmov */
"bsfl %1, %0;\n\t"
"jnz 1f;\n\t"
"movl $-1, %0;\n\t"
"1:\n\t"
: "=r" (bitpos)
: "rm" (op)
: "cc"
#else
"bsfl %1, %0;\n\t"
"cmovzl %2, %0;\n\t"
: "=r" (bitpos)
: "rm" (op), "r" (-1)
: "cc"
#endif /* CONFIG_CPU_MINUTEIA */
);
return (bitpos + 1);
}
/**
*
* @brief find most significant bit set in a 32-bit word
*
* This routine finds the first bit set starting from the most significant bit
* in the argument passed in and returns the index of that bit. Bits are
* numbered starting at 1 from the least significant bit. A return value of
* zero indicates that the value passed is zero.
*
* @return most significant bit set, 0 if @a op is 0
*
* @internal
* For Intel64 (x86_64) architectures, the 'cmovzl' can be removed and leverage
* the fact that the 'bsfl' doesn't modify the destination operand when the
* source operand is zero. The "bitpos" variable can be preloaded into the
* destination register, and given the unconditional ++bitpos that is performed
* after the 'cmovzl', the correct results are yielded.
*/
static ALWAYS_INLINE unsigned int find_msb_set(u32_t op)
{
unsigned int bitpos;
__asm__ volatile (
#ifdef CONFIG_CPU_MINUTEIA
/* again, Minute IA doesn't support cmov */
"bsrl %1, %0;\n\t"
"jnz 1f;\n\t"
"movl $-1, %0;\n\t"
"1:\n\t"
: "=r" (bitpos)
: "rm" (op)
: "cc"
#else
"bsrl %1, %0;\n\t"
"cmovzl %2, %0;\n\t"
: "=r" (bitpos)
: "rm" (op), "r" (-1)
#endif /* CONFIG_CPU_MINUTEIA */
);
return (bitpos + 1);
}
#endif /* _ASMLANGUAGE */
#ifdef __cplusplus
}
#endif
#endif /* ZEPHYR_INCLUDE_ARCH_X86_FFS_H_ */

2
include/arch/x86/ia32/arch.h
View file

@ -21,7 +21,7 @@
#include <mmustructs.h> #include <mmustructs.h>
#include <stdbool.h> #include <stdbool.h>
#include "../sys_io.h" #include "../sys_io.h"
#include "../ffs.h" #include <arch/common/ffs.h>
#ifndef _ASMLANGUAGE #ifndef _ASMLANGUAGE
#include <arch/x86/asm_inline.h> #include <arch/x86/asm_inline.h>