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use core::ptr::RawPtr;
// use rust_core::c_types::c_int;

mod stack;

// TODO: use SSE

#[inline]
fn stosb(s: *mut u8, c: u8, n: uint) {
    unsafe {
        asm!("rep stosb" :: "{al}"(c), "{edi}"(s), "{ecx}"(n))
    }
}

#[inline]
fn stosd(s: *mut u8, c: u32, n: uint) {
    unsafe {
        asm!("rep stosl" :: "A"(c), "{edi}"(s), "{ecx}"(n))
    }
}

#[inline]
fn stosd8(s: *mut u8, c: u8, n: uint) {
    unsafe {
        let mut dword: u32 = c as u32;
        dword |= (dword << 24) | (dword << 16) | (dword << 8);
        asm!("rep stosl" :: "A"(dword), "{edi}"(s), "{ecx}"(n))
    }
}

#[inline]
fn stosd16(s: *mut u8, c: u16, n: uint) {
    unsafe {
        let mut dword: u32 = c as u32;
        dword |= dword << 16;
        asm!("rep stosl" :: "A"(dword), "{edi}"(s), "{ecx}"(n))
    }
}

#[inline]
fn memset_nonzero(mut s: *mut u8, c: u8, mut n: uint) {
    if unlikely!(n == 0) {
        return
    }
    if unlikely!(n == 1) {
        unsafe { *s = c; }
        return
    }

    while n > 0 {
        match n % 4 {
            0 => {
                stosd8(s, c, n / 4);
                n = 0;
            }
            /*2 => unsafe {
                let mut word: u16 = c as u16;
                word = (word << 8) | word;
                asm!("rep stosw" :: "A"(word), "{edi}"(s), "{ecx}"(n / 2))
                n = 0;
            },*/
            q => {
                stosb(s, c, q);
                s = unsafe { s.offset(q as int) };
                n -= q;
            }
        }
    }
}

pub fn wmemset(mut dest: *mut u8, c: u16, n: uint) {
    if unlikely!(n == 0) {
        return;
    }

    if (n % 2) == 1 {
        unsafe {
            *(dest as *mut u16) = c;
            dest = dest.offset(2);
        }
    }

    stosd16(dest, c, n >> 1);
}

fn dmemset(s: *mut u8, c: u32, n: uint) {
    if unlikely!(n == 0) {
        return;
    }

    stosd(s, c, n);
}

#[no_mangle]
pub fn memset(s: *mut u8, c: i32, n: int) {
    memset_nonzero(s, (c & 0xFF) as u8, n as uint);
}

#[allow(dead_assignment)]
#[no_mangle]
pub fn memcpy(dest: *mut u8, src: *const u8, mut n: uint) {
    if unlikely!(n == 0) {
        return;
    }
    unsafe {
        if n < 12 {
            asm!("rep movsb" :: "{edi}"(dest), "{esi}"(src), "{ecx}"(n))
            return;
        }

        let offset = (4 - (dest as uint % 4)) % 4;
        n -= offset;

        let mut pd: *mut u8;
        let mut ps: *const u8;
        asm!("rep movsb" : "={edi}"(pd), "={esi}"(ps) : "{edi}"(dest), "{esi}"(src), "{ecx}"(offset))
        asm!("rep movsl" : "={edi}"(pd), "={esi}"(ps) : "{edi}"(pd), "{esi}"(ps), "{ecx}"(n >> 2))
        asm!("rep movsb" :: "{edi}"(pd), "{esi}"(ps), "{ecx}"(n % 4))
    }
}

#[no_mangle]
pub fn memmove(dest: *mut u8, src: *const u8, n: uint) {
    unsafe {
        if src < dest as *const u8 {
            asm!("std")
            memcpy(dest.offset(n as int), src.offset(n as int), n);
            asm!("cld")
        }
        else {
            asm!("cld")
            memcpy(dest, src, n);
        }
    }
}

#[no_mangle]
pub unsafe fn memcmp(s1: *const u8, s2: *const u8, n: uint) -> i32 {
    let mut i = 0;
    while i < n {
        let a = *s1.offset(i as int);
        let b = *s2.offset(i as int);
        if a != b {
            return (a - b) as i32
        }
        i += 1;
    }
    return 0;
}