// SPDX-License-Identifier: GPL-2.0

  /*
   * Copyright (C) 2003 Bernardo Innocenti <bernie@develer.com>
   *
   * Based on former do_div() implementation from asm-parisc/div64.h:
   *	Copyright (C) 1999 Hewlett-Packard Co
   *	Copyright (C) 1999 David Mosberger-Tang <davidm@hpl.hp.com>
   *
   *
   * Generic C version of 64bit/32bit division and modulo, with
   * 64bit result and 32bit remainder.
   *
   * The fast case for (n>>32 == 0) is handled inline by do_div(). 
   *
   * Code generated for this function might be very inefficient
   * for some CPUs. __div64_32() can be overridden by linking arch-specific

   * assembly versions such as arch/ppc/lib/div64.S and arch/sh/lib/div64.S
   * or by defining a preprocessor macro in arch/include/asm/div64.h.

   */

  #include <linux/export.h>
  #include <linux/kernel.h>

  #include <linux/math64.h>

  
  /* Not needed on 64bit architectures */
  #if BITS_PER_LONG == 32

  #ifndef __div64_32

  uint32_t __attribute__((weak)) __div64_32(uint64_t *n, uint32_t base)

  {
  	uint64_t rem = *n;
  	uint64_t b = base;
  	uint64_t res, d = 1;
  	uint32_t high = rem >> 32;
  
  	/* Reduce the thing a bit first */
  	res = 0;
  	if (high >= base) {
  		high /= base;
  		res = (uint64_t) high << 32;
  		rem -= (uint64_t) (high*base) << 32;
  	}
  
  	while ((int64_t)b > 0 && b < rem) {
  		b = b+b;
  		d = d+d;
  	}
  
  	do {
  		if (rem >= b) {
  			rem -= b;
  			res += d;
  		}
  		b >>= 1;
  		d >>= 1;
  	} while (d);
  
  	*n = res;
  	return rem;
  }

  EXPORT_SYMBOL(__div64_32);

  #endif

  /**
   * div_s64_rem - signed 64bit divide with 64bit divisor and remainder
   * @dividend:	64bit dividend
   * @divisor:	64bit divisor
   * @remainder:  64bit remainder
   */

  #ifndef div_s64_rem
  s64 div_s64_rem(s64 dividend, s32 divisor, s32 *remainder)
  {
  	u64 quotient;
  
  	if (dividend < 0) {
  		quotient = div_u64_rem(-dividend, abs(divisor), (u32 *)remainder);
  		*remainder = -*remainder;
  		if (divisor > 0)
  			quotient = -quotient;
  	} else {
  		quotient = div_u64_rem(dividend, abs(divisor), (u32 *)remainder);
  		if (divisor < 0)
  			quotient = -quotient;
  	}
  	return quotient;
  }
  EXPORT_SYMBOL(div_s64_rem);
  #endif

  /**

   * div64_u64_rem - unsigned 64bit divide with 64bit divisor and remainder
   * @dividend:	64bit dividend
   * @divisor:	64bit divisor
   * @remainder:  64bit remainder
   *
   * This implementation is a comparable to algorithm used by div64_u64.
   * But this operation, which includes math for calculating the remainder,
   * is kept distinct to avoid slowing down the div64_u64 operation on 32bit
   * systems.
   */
  #ifndef div64_u64_rem
  u64 div64_u64_rem(u64 dividend, u64 divisor, u64 *remainder)
  {
  	u32 high = divisor >> 32;
  	u64 quot;
  
  	if (high == 0) {
  		u32 rem32;
  		quot = div_u64_rem(dividend, divisor, &rem32);
  		*remainder = rem32;
  	} else {
  		int n = 1 + fls(high);
  		quot = div_u64(dividend >> n, divisor >> n);
  
  		if (quot != 0)
  			quot--;
  
  		*remainder = dividend - quot * divisor;
  		if (*remainder >= divisor) {
  			quot++;
  			*remainder -= divisor;
  		}
  	}
  
  	return quot;
  }
  EXPORT_SYMBOL(div64_u64_rem);
  #endif
  
  /**

   * div64_u64 - unsigned 64bit divide with 64bit divisor

   * @dividend:	64bit dividend
   * @divisor:	64bit divisor
   *
   * This implementation is a modified version of the algorithm proposed
   * by the book 'Hacker's Delight'.  The original source and full proof
   * can be found here and is available for use without restriction.
   *

   * 'http://www.hackersdelight.org/hdcodetxt/divDouble.c.txt'

   */

  #ifndef div64_u64
  u64 div64_u64(u64 dividend, u64 divisor)

  {

  	u32 high = divisor >> 32;
  	u64 quot;

  	if (high == 0) {

  		quot = div_u64(dividend, divisor);

  	} else {
  		int n = 1 + fls(high);
  		quot = div_u64(dividend >> n, divisor >> n);

  		if (quot != 0)
  			quot--;

  		if ((dividend - quot * divisor) >= divisor)

  			quot++;
  	}

  	return quot;

  }

  EXPORT_SYMBOL(div64_u64);

  #endif

  /**
   * div64_s64 - signed 64bit divide with 64bit divisor
   * @dividend:	64bit dividend
   * @divisor:	64bit divisor
   */
  #ifndef div64_s64
  s64 div64_s64(s64 dividend, s64 divisor)
  {
  	s64 quot, t;

  	quot = div64_u64(abs(dividend), abs(divisor));

  	t = (dividend ^ divisor) >> 63;
  
  	return (quot ^ t) - t;
  }
  EXPORT_SYMBOL(div64_s64);
  #endif

  #endif /* BITS_PER_LONG == 32 */

  
  /*
   * Iterative div/mod for use when dividend is not expected to be much
   * bigger than divisor.
   */
  u32 iter_div_u64_rem(u64 dividend, u32 divisor, u64 *remainder)
  {

  	return __iter_div_u64_rem(dividend, divisor, remainder);

  }
  EXPORT_SYMBOL(iter_div_u64_rem);