From 9eafc640fdcfc0a0e8c463501b4a18ea91f8f14e Mon Sep 17 00:00:00 2001
From: mykola2312 <49044616+mykola2312@users.noreply.github.com>
Date: Sun, 15 May 2022 22:23:48 +0300
Subject: [PATCH] fix _cu_memmove in assembly, now it's byte-by-byte moving

---
 arch/x86_64.S | 22 ----------------------
 test.c        |  5 ++++-
 2 files changed, 4 insertions(+), 23 deletions(-)

diff --git a/arch/x86_64.S b/arch/x86_64.S
index 55f7b79..60a7c04 100644
--- a/arch/x86_64.S
+++ b/arch/x86_64.S
@@ -46,36 +46,14 @@ _cu_memmove:
     add %rdx, %rdi
     add %rdx, %rsi
     std
-    mov %rdx, %rcx
-    shr $3, %rcx
-    je .greater1_
-    sub $8, %rdi
-    sub $8, %rsi
-    rep movsq
-.greater1:
-    add $8, %rdi
-    add $8, %rsi
-    mov %rdx, %rcx
-    and $7, %rcx
-    rep movsb
-    cld
-    jmp .retmove
-.greater1_:
     dec %rdi
     dec %rsi
     mov %rdx, %rcx
-    and $7, %rcx
     rep movsb
     cld
     jmp .retmove
 .lessmove:      // dst < src
     mov %rdx, %rcx
-    shr $3, %rcx
-    je .less1
-    rep movsq
-.less1:
-    mov %rdx, %rcx
-    and $7, %rcx
     rep movsb
 .retmove:
     ret
diff --git a/test.c b/test.c
index 0e63860..d84b7dd 100644
--- a/test.c
+++ b/test.c
@@ -121,7 +121,10 @@ int main()
         printf("\t%u\n", val4[i]);
     printf("\n");
     
-    _cu_memmove(&val4[1], &val4[0], sizeof(uint) * 3);
+    void* dst = &val4[1];
+    void* src = &val4[0];
+    printf("memmove delta\t%lx\n", (uintptr_t)dst - (uintptr_t)src);
+    _cu_memmove(dst, src, sizeof(uint) * 3);
     printf("val4 memmove ->\n");
     for (unsigned i = 0; i < 5; i++)
         printf("\t%u\n", val4[i]);