/* Floating point library in optimized assembly for 8051
 * Copyright (c) 2004, Paul Stoffregen, paul@pjrc.com
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Library General Public License
 * as published by the Free Software Foundation; either version 2
 * of the License, or (at your option) any later version.
 *
 * This library is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.
 */


#define SDCC_FLOAT_LIB
#include <float.h>


#ifdef FLOAT_ASM_MCS51

// float __fsmul (float a, float b) reentrant
static void dummy(void) _naked
{
	_asm
	.globl	___fsmul
___fsmul:
	// extract the two inputs, placing them into:
	//      sign     exponent   mantissa
	//      ----     --------   --------
	//  a:  sign_a   exp_a      r4/r3/r2
	//  b:  sign_b   exp_b      r7/r6/r5

	lcall	fsgetargs

	// first check if either input is zero
	cjne	r4, #0, 00002$
00001$:
	ljmp	fs_return_zero

00002$:
	mov	a, r7
	jz	00001$

	// compute final sign bit
	jnb	sign_b, 00003$
	cpl	sign_a
00003$:

	// add the exponents
	mov	a, exp_a
	add	a, exp_b
	add	a, #130
	mov	exp_a, a


	// now we need to multipy r4/r3/r2 * r7/r6/r5
	// ------------------------------------------
	//	                        r2 * r5		<< 0
	//	            r3 * r5  +  r2 * r6		<< 8
	//	r4 * r5  +  r3 * r6  +  r2 * r7		<< 16
	//	r4 * r6  +  r3 * r7			<< 24
	//	r4 * r7					<< 32
	//
	// This adds quite a bit of code, but it is a LOT faster
	// than three calls to __mululong...

	// output goes into r4/r3/r2/r1/r0/xx

	mov	a, r2
	mov	b, r5
	mul	ab			// r2 * r5
	// discard lowest 8 bits
	mov	r0, b
	// range 0-FE

	mov	a, r2
	mov	b, r6
	mul	ab			// r2 * r6
	add	a, r0
	mov	r0, a
	clr	a
	addc	a, b
	mov	r1, a
	// range 0-FEFF

	mov	a, r3
	mov	b, r5
	mul	ab			// r3 * r5
	add	a, r0
	// discard lowest 8 bits
	mov	a, r1
	addc	a, b
	mov	r1, a
	clr	a
	rlc	a
	xch	a, r2
	// range 0-1FD

	mov	b, r7
	mul	ab			// r2 * r7
	add	a, r1
	mov	r1, a
	mov	a, r2
	addc	a, b
	mov	r2, a
	// range 0-FFFE

	mov	a, r3
	mov	r0, a
	mov	b, r6
	mul	ab			// r3 * r6
	add	a, r1
	mov	r1, a
	mov	a, r2
	addc	a, b
	mov	r2, a
	clr	a
	rlc	a
	mov	r3, a
	// range 0-1FDFF

	mov	a, r4
	mov	b, r5
	mul	ab			// r4 * r5
	add	a, r1
	mov	r1, a
	mov	a, r2
	addc	a, b
	mov	r2, a
	clr	a
	addc	a, r3
	mov	r3, a
	// range 0-2FC00

	mov	a, r0 // r3
	mov	b, r7
	mul	ab			// r3 * r7
	add	a, r2
	mov	r2, a
	mov	a, r3
	addc	a, b
	mov	r3, a
	clr	a
	rlc	a
	xch	a, r4
	// range 0-100FD00

	mov	r5, a
	mov	b, r6
	mul	ab			// r4 * r6
	add	a, r2
	mov	r2, a
	mov	a, r3
	addc	a, b
	mov	r3, a
	clr	a
	addc	a, r4
	mov	r4, a
	// range 0-1FEFE00

	mov	a, r5 // r4
	mov	b, r7
	mul	ab			// r4 * r7
	add	a, r3
	mov	r3, a
	mov	a, r4
	addc	a, b
	mov	r4, a
	// range 40000000-FFFFFE00

	jb	acc.7, 00010$
	lcall	fs_normalize_a

00010$:
	ljmp	fs_round_and_return
	_endasm;
}

#else


/*
** libgcc support for software floating point.
** Copyright (C) 1991 by Pipeline Associates, Inc.  All rights reserved.
** Permission is granted to do *anything* you want with this file,
** commercial or otherwise, provided this message remains intact.  So there!
** I would appreciate receiving any updates/patches/changes that anyone
** makes, and am willing to be the repository for said changes (am I
** making a big mistake?).
**
** Pat Wood
** Pipeline Associates, Inc.
** pipeline!phw@motown.com or
** sun!pipeline!phw or
** uunet!motown!pipeline!phw
*/

/* (c)2000/2001: hacked a little by johan.knol@iduna.nl for sdcc */


union float_long
  {
    float f;
    unsigned long l;
  };

/* multiply two floats */
float __fsmul (float a1, float a2) {
  volatile union float_long fl1, fl2;
  volatile unsigned long result;
  volatile int exp;
  char sign;
  
  fl1.f = a1;
  fl2.f = a2;

  if (!fl1.l || !fl2.l)
    return (0);

  /* compute sign and exponent */
  sign = SIGN (fl1.l) ^ SIGN (fl2.l);
  exp = EXP (fl1.l) - EXCESS;
  exp += EXP (fl2.l);

  fl1.l = MANT (fl1.l);
  fl2.l = MANT (fl2.l);

  /* the multiply is done as one 16x16 multiply and two 16x8 multiples */
  result = (fl1.l >> 8) * (fl2.l >> 8);
  result += ((fl1.l & (unsigned long) 0xFF) * (fl2.l >> 8)) >> 8;
  result += ((fl2.l & (unsigned long) 0xFF) * (fl1.l >> 8)) >> 8;

  if (result & SIGNBIT)
    {
      /* round */
      result += 0x80;
      result >>= 8;
    }
  else
    {
      /* round */
      result += 0x40;
      result >>= 7;
      exp--;
    }

  result &= ~HIDDEN;

  /* pack up and go home */
  fl1.l = PACK (sign ? SIGNBIT : 0 , (unsigned long)exp, result);  
  return (fl1.f);
}

#endif

