/* SPDX-License-Identifier: GPL-2.0 */ #include <linux/export.h> #include <linux/linkage.h> #include <asm/asm.h> /* * unsigned int __sw_hweight32(unsigned int w) * %rdi: w */ SYM_FUNC_START(__sw_hweight32) #ifdef CONFIG_X86_64 movl %edi, %eax # w #endif __ASM_SIZE(push,) %__ASM_REG(dx) movl %eax, %edx # w -> t shrl %edx # t >>= 1 andl $0x55555555, %edx # t &= 0x55555555 subl %edx, %eax # w -= t movl %eax, %edx # w -> t shrl $2, %eax # w_tmp >>= 2 andl $0x33333333, %edx # t &= 0x33333333 andl $0x33333333, %eax # w_tmp &= 0x33333333 addl %edx, %eax # w = w_tmp + t movl %eax, %edx # w -> t shrl $4, %edx # t >>= 4 addl %edx, %eax # w_tmp += t andl $0x0f0f0f0f, %eax # w_tmp &= 0x0f0f0f0f imull $0x01010101, %eax, %eax # w_tmp *= 0x01010101 shrl $24, %eax # w = w_tmp >> 24 __ASM_SIZE(pop,) %__ASM_REG(dx) RET SYM_FUNC_END(__sw_hweight32) EXPORT_SYMBOL(__sw_hweight32) /* * No 32-bit variant, because it's implemented as an inline wrapper * on top of __arch_hweight32(): */ #ifdef CONFIG_X86_64 SYM_FUNC_START(__sw_hweight64) pushq %rdi pushq %rdx movq %rdi, %rdx # w -> t movabsq $0x5555555555555555, %rax shrq %rdx # t >>= 1 andq %rdx, %rax # t &= 0x5555555555555555 movabsq $0x3333333333333333, %rdx subq %rax, %rdi # w -= t movq %rdi, %rax # w -> t shrq $2, %rdi # w_tmp >>= 2 andq %rdx, %rax # t &= 0x3333333333333333 andq %rdi, %rdx # w_tmp &= 0x3333333333333333 addq %rdx, %rax # w = w_tmp + t movq %rax, %rdx # w -> t shrq $4, %rdx # t >>= 4 addq %rdx, %rax # w_tmp += t movabsq $0x0f0f0f0f0f0f0f0f, %rdx andq %rdx, %rax # w_tmp &= 0x0f0f0f0f0f0f0f0f movabsq $0x0101010101010101, %rdx imulq %rdx, %rax # w_tmp *= 0x0101010101010101 shrq $56, %rax # w = w_tmp >> 56 popq %rdx popq %rdi RET SYM_FUNC_END(__sw_hweight64) EXPORT_SYMBOL(__sw_hweight64) #endif
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