LibC: Write memchr, memcmp and strlen with sse

userspace/libraries/LibC/arch/i686/string.S

@@ -1,35 +1,3 @@
-.global memchr
-memchr:
-	xchgl 4(%esp), %edi
-	movl  8(%esp), %eax
-	movl 12(%esp), %ecx
-	movl $1, %edx
-	cmpl $1, %ecx # clear ZF if count is zero
-	repne scasb
-	cmovel %edi, %edx
-	leal -1(%edx), %eax
-	movl 4(%esp), %edi
-	ret
-
-.global memcmp
-memcmp:
-	xchgl 4(%esp), %edi
-	xchgl 8(%esp), %esi
-	movl 12(%esp), %ecx
-	testl %ecx, %ecx # set ZF if count is zero
-	repe cmpsb
-	jne .memcmp_not_equal
-	xorl %eax, %eax
-	jmp .memcmp_done
- .memcmp_not_equal:
-	movzbl -1(%edi), %eax
-	movzbl -1(%esi), %ecx
-	subl %ecx, %eax
- .memcmp_done:
-	movl 4(%esp), %edi
-	movl 8(%esp), %esi
-	ret
-
 .global memcpy
 memcpy:
 	xchgl 4(%esp), %edi
@@ -74,14 +42,3 @@ memset:
 	movl 4(%esp), %edi
 	movl %edx, %eax
 	ret
-
-.global strlen
-strlen:
-	xchgl 4(%esp), %edi
-	xorb %al, %al
-	movl $-1, %ecx
-	repne scasb
-	movl 4(%esp), %edi
-	movl $-2, %eax
-	subl %ecx, %eax
-	ret

userspace/libraries/LibC/arch/x86_64/string.S

@@ -1,28 +1,3 @@
-.global memchr
-memchr:
-	movb %sil, %al
-	movq %rdx, %rcx
-	movq $1, %rdx
-	cmpq $1, %rcx # clear ZF if count is zero
-	repne scasb
-	cmoveq %rdi, %rdx
-	leaq -1(%rdx), %rax
-	ret
-
-.global memcmp
-memcmp:
-	movq %rdx, %rcx
-	testq %rcx, %rcx # set ZF if count is zero
-	repe cmpsb
-	jne .memcmp_not_equal
-	xorq %rax, %rax
-	ret
- .memcmp_not_equal:
-	movzbl -1(%rdi), %eax
-	movzbl -1(%rsi), %ecx
-	subq %rcx, %rax
-	ret
-
 .global memcpy
 memcpy:
 	movq %rdi, %rax
@@ -52,11 +27,154 @@ memset:
 	movq %r8, %rax
 	ret
 
+
+#if defined(__SSE2__)
+
+.global memchr
+memchr:
+	testq %rdx, %rdx
+	jz .memchr_no_match
+
+	movd %esi, %xmm0
+	punpcklbw %xmm0, %xmm0
+	punpcklwd %xmm0, %xmm0
+	pshufd $0, %xmm0, %xmm0
+
+	movq %rdi, %rcx
+	andq $15, %rcx
+	jz .memchr_loop
+
+	movq %rdi, %rsi
+	subq %rcx, %rsi
+	movdqa (%rsi), %xmm1
+	pcmpeqb %xmm0, %xmm1
+	pmovmskb %xmm1, %eax
+	shrl %cl, %eax
+	jnz .memchr_match
+
+	leaq 16(%rsi), %rdi
+
+	addq %rcx, %rdx
+	subq $16, %rdx
+	jbe .memchr_no_match
+
+ .memchr_loop:
+	movdqa (%rdi), %xmm1
+	pcmpeqb %xmm0, %xmm1
+	pmovmskb %xmm1, %eax
+	testl %eax, %eax
+	jnz .memchr_match
+
+	addq $16, %rdi
+	subq $16, %rdx
+	ja .memchr_loop
+
+ .memchr_no_match:
+	xorq %rax, %rax
+	ret
+
+ .memchr_match:
+	bsfl %eax, %eax
+	cmpq %rdx, %rax
+	jae .memchr_no_match
+	addq %rdi, %rax
+	ret
+
+.global memcmp
+memcmp:
+	testq %rdx, %rdx
+	jz .memcmp_equal
+
+	movq %rdi, %rax
+	movq %rsi, %rcx
+	andq $15, %rax
+	andq $15, %rcx
+	cmpq %rax, %rcx
+	cmovaq %rcx, %rax
+
+	testq %rax, %rax
+	jz .memcmp_loop
+
+	movq $16, %rcx
+	subq %rax, %rcx
+
+	cmpq %rcx, %rdx
+	cmovbq %rdx, %rcx
+
+	subq %rcx, %rdx
+
+ .memcmp_align_loop:
+	movzbl (%rdi), %eax
+	movzbl (%rsi), %r8d
+	subl %r8d, %eax
+	jnz .memcmp_return
+
+	incq %rdi
+	incq %rsi
+	decq %rcx
+	jnz .memcmp_align_loop
+
+ .memcmp_loop:
+	movdqu (%rdi), %xmm0
+	movdqu (%rsi), %xmm1
+	pcmpeqb %xmm0, %xmm1
+	pmovmskb %xmm1, %eax
+	xorl $0xFFFF, %eax
+	jnz .memcmp_differ
+
+	addq $16, %rdi
+	addq $16, %rsi
+	subq $16, %rdx
+	ja .memcmp_loop
+
+ .memcmp_equal:
+	xorl %eax, %eax
+ .memcmp_return:
+	ret
+
+ .memcmp_differ:
+	bsfl %eax, %ecx
+	cmpq %rdx, %rcx
+	jae .memcmp_equal
+	movzbl (%rdi, %rcx), %eax
+	movzbl (%rsi, %rcx), %edx
+	subl %edx, %eax
+	ret
+
 .global strlen
 strlen:
-	xorb %al, %al
+	movq %rdi, %rsi
-	movq $-1, %rcx
+
-	repne scasb
+	pxor %xmm0, %xmm0
-	movq $-2, %rax
+
-	subq %rcx, %rax
+	movq %rsi, %rcx
+	andq $15, %rcx
+	jz .strlen_loop
+
+	movq %rsi, %rdx
+	subq %rcx, %rdx
+	movdqa (%rdx), %xmm1
+	pcmpeqb %xmm0, %xmm1
+	pmovmskb %xmm1, %eax
+	shrl %cl, %eax
+	jnz .strlen_null_found
+
+	leaq 16(%rdx), %rsi
+
+ .strlen_loop:
+	movdqa (%rsi), %xmm1
+	pcmpeqb %xmm0, %xmm1
+	pmovmskb %xmm1, %eax
+	testl %eax, %eax
+	jnz .strlen_null_found
+
+	addq $16, %rsi
+	jmp .strlen_loop
+
+ .strlen_null_found:
+	bsfl %eax, %eax
+	addq %rsi, %rax
+	subq %rdi, %rax
 	ret
+
+#endif