ModRM 
==================


mov rbx, [rcx + 0x40]
-----------------------

pushfq
pushaq
lea rdx, [rcx + 0x40]

# we use rbp to save rsp value
# this is safe because both Windows x64 ABI and SystemV x64 ABI 
# guarantees rbp must be saved and restored by a function that uses them
mov rbp, rsp

sub rsp, 0x20
and rsp, 0xFFFFFFFFFFFFFFF0

mov rcx, this
mov r8, 8
mov r9, rbx
mov rax, OnMemoryRead
call rax

mov rsp, rbp
popaq
popfq

mov rbx, [rcx + 0x40]






and [rcx + 0x40], rbx 
-----------------------

pushfq
pushaq
lea rdx, [rcx + 0x40]

# we use rbp to save rsp value
# this is safe because both Windows x64 ABI and SystemV x64 ABI 
# guarantees rbp must be saved and restored by a function that uses them
mov rbp, rsp

sub rsp, 0x20
and rsp, 0xFFFFFFFFFFFFFFF0

mov rcx, this
mov r8, 8
mov rax, OnMemoryRead
call rax

mov rsp, rbp
popaq
popfq


push r15  # r15 is free reg which the instruction doesn't use, including hidden operands.
lea r15, [rcx + 0x40]
mov [rcx + 0x40], rbx  # execute original insturction before callback


pushfq
pushaq
mov rdx, r15

# we use rbp to save rsp value
# this is safe because both Windows x64 ABI and SystemV x64 ABI 
# guarantees rbp must be saved and restored by a function that uses them
mov rbp, rsp

sub rsp, 0x20
and rsp, 0xFFFFFFFFFFFFFFF0

mov rcx, this
mov r8, 8
mov rax, OnMemoryWrite
call rax

mov rsp, rbp
popaq
popfq

pop r15









rep movsd
==================



pushfq
pushaq
mov rbp, rsp

sub rsp, 0x20
and rsp, 0xFFFFFFFFFFFFFFF0

mov r15, rcx
shl r15, 2          # 1 for w, 2 for d, 3 for q


pushfq
pop rax
bt rax, 0x0A        # DF
jnc label           # if CF=0

sub rsi, r15

label:

mov rcx, this
mov rdx, rsi
mov r8, r15
mov rax, OnMemoryRead
call rax

mov rsp, rbp
popaq
popfq



push r15
mov r15, rcx
rep movsd



pushfq
pushaq
mov rbp, rsp

sub rsp, 0x20
and rsp, 0xFFFFFFFFFFFFFFF0

sub r15, rcx
shl r15, 2          # 1 for w, 2 for d, 3 for q

pushfq
pop rax
bt rax, 0x0A        # DF
jc label           # if CF=1

sub rdi, r15

label:

mov rcx, this
mov rdx, rdi
mov r8, r15
mov rax, OnMemoryWrite
call rax

mov rsp, rbp
popaq
popfq
pop r15





      
vpgatherdd  ymm19{k1},dword ptr [rax+ymm2]
62 E2 7D 29 90 1C 10