#pragma once

#include "types.h"
#include "util/debug.h"

/* Approximate numbers taken from various points in Linux kernel */
#define LOOPS_PER_JIFFY (1 << 12)
#define HZ 100 /* Found this in a random place in the kernel */

/* From arch/x86/lib/delay.c in Linux kernel */
/*
 *      Precise Delay Loops for i386
 *
 *      Copyright (C) 1993 Linus Torvalds
 *      Copyright (C) 1997 Martin Mares <mj@atrey.karlin.mff.cuni.cz>
 *      Copyright (C) 2008 Jiri Hladky <hladky _dot_ jiri _at_ gmail _dot_ com>
 *
 *      The __delay function must _NOT_ be inlined as its execution time
 *      depends wildly on alignment on many x86 processors. The additional
 *      jump magic is needed to get the timing stable on all the CPU's
 *      we have to worry about.
 */

static void __delay(unsigned long loops)
{
    __asm__ volatile(
        "	test %0,%0	\n"
        "	jz 3f		\n"
        "	jmp 1f		\n"

        ".align 16		\n"
        "1:	jmp 2f		\n"

        ".align 16		\n"
        "2:	dec %0		\n"
        "	jnz 2b		\n"
        "3:	dec %0		\n"

        : /* we don't need output */
        : "a"(loops));
}

static inline void __const_udelay(unsigned long xloops)
{
    int d0;

    xloops *= 4;
    __asm__ volatile("mull %%edx"
                     : "=d"(xloops), "=&a"(d0)
                     : "1"(xloops), "0"(LOOPS_PER_JIFFY * (HZ / 4)));

    __delay(++xloops);
}

static inline void __udelay(unsigned long usecs)
{
    __const_udelay(usecs * 4295); /* 2**32 / 1000000 */
}

static inline void __ndelay(unsigned long nsecs)
{
    __const_udelay(nsecs * 5); /* 2**32 / 1000000000 */
}

#define udelay(n)                                                       \
    (__builtin_constant_p(n) ? ((n) > 20000 ? panic("Delay too large!") \
                                            : __const_udelay((n)*4295)) \
                             : __udelay(n))

#define ndelay(n)                                                            \
    (__builtin_constant_p(n)                                                 \
         ? ((n) > 20000 ? panic("Delay too large!") : __const_udelay((n)*5)) \
         : __ndelay(n))