[linux.git] / arch / blackfin / lib / divsi3.S

/*
 * Copyright 2004-2009 Analog Devices Inc.
 *
 * Licensed under the Clear BSD license or the GPL-2 (or later)
 *
 * 16 / 32 bit signed division.
 *                 Special cases :
 *                      1)  If(numerator == 0)
 *                             return 0
 *                      2)  If(denominator ==0)
 *                             return positive max = 0x7fffffff
 *                      3)  If(numerator == denominator)
 *                             return 1
 *                      4)  If(denominator ==1)
 *                             return numerator
 *                      5)  If(denominator == -1)
 *                             return -numerator
 *
 *                 Operand         : R0 - Numerator   (i)
 *                                   R1 - Denominator (i)
 *                                   R0 - Quotient    (o)
 *                 Registers Used : R2-R7,P0-P2
 *
 */

.global   ___divsi3;
.type ___divsi3, STT_FUNC;

#ifdef CONFIG_ARITHMETIC_OPS_L1
.section .l1.text
#else
.text
#endif

.align 2;
___divsi3 :


  R3 = R0 ^ R1;
  R0 = ABS R0;

  CC = V;

  r3 = rot r3 by -1;
  r1 = abs r1;      /* now both positive, r3.30 means "negate result",
                    ** r3.31 means overflow, add one to result
                    */
  cc = r0 < r1;
  if cc jump .Lret_zero;
  r2 = r1 >> 15;
  cc = r2;
  if cc jump .Lidents;
  r2 = r1 << 16;
  cc = r2 <= r0;
  if cc jump .Lidents;

  DIVS(R0, R1);
  DIVQ(R0, R1);
  DIVQ(R0, R1);
  DIVQ(R0, R1);
  DIVQ(R0, R1);
  DIVQ(R0, R1);
  DIVQ(R0, R1);
  DIVQ(R0, R1);
  DIVQ(R0, R1);
  DIVQ(R0, R1);
  DIVQ(R0, R1);
  DIVQ(R0, R1);
  DIVQ(R0, R1);
  DIVQ(R0, R1);
  DIVQ(R0, R1);
  DIVQ(R0, R1);
  DIVQ(R0, R1);

  R0 = R0.L (Z);
  r1 = r3 >> 31;    /* add overflow issue back in */
  r0 = r0 + r1;
  r1 = -r0;
  cc = bittst(r3, 30);
  if cc r0 = r1;
  RTS;

/* Can't use the primitives. Test common identities.
** If the identity is true, return the value in R2.
*/

.Lidents:
  CC = R1 == 0;                   /* check for divide by zero */
  IF CC JUMP .Lident_return;

  CC = R0 == 0;                   /* check for division of zero */
  IF CC JUMP .Lzero_return;

  CC = R0 == R1;                  /* check for identical operands */
  IF CC JUMP .Lident_return;

  CC = R1 == 1;                   /* check for divide by 1 */
  IF CC JUMP .Lident_return;

  R2.L = ONES R1;
  R2 = R2.L (Z);
  CC = R2 == 1;
  IF CC JUMP .Lpower_of_two;

  /* Identities haven't helped either.
  ** Perform the full division process.
  */

  P1 = 31;                        /* Set loop counter   */

  [--SP] = (R7:5);                /* Push registers R5-R7 */
  R2 = -R1;
  [--SP] = R2;
  R2 = R0 << 1;                   /* R2 lsw of dividend  */
  R6 = R0 ^ R1;                   /* Get sign */
  R5 = R6 >> 31;                  /* Shift sign to LSB */

  R0 = 0 ;                        /* Clear msw partial remainder */
  R2 = R2 | R5;                   /* Shift quotient bit */
  R6 = R0 ^ R1;                   /* Get new quotient bit */

  LSETUP(.Llst,.Llend)  LC0 = P1;   /* Setup loop */
.Llst:   R7 = R2 >> 31;            /* record copy of carry from R2 */
        R2 = R2 << 1;             /* Shift 64 bit dividend up by 1 bit */
        R0 = R0 << 1 || R5 = [SP];
        R0 = R0 | R7;             /* and add carry */
        CC = R6 < 0;              /* Check quotient(AQ) */
                                  /* we might be subtracting divisor (AQ==0) */
        IF CC R5 = R1;            /* or we might be adding divisor  (AQ==1)*/
        R0 = R0 + R5;             /* do add or subtract, as indicated by AQ */
        R6 = R0 ^ R1;             /* Generate next quotient bit */
        R5 = R6 >> 31;
                                  /* Assume AQ==1, shift in zero */
        BITTGL(R5,0);             /* tweak AQ to be what we want to shift in */
.Llend:  R2 = R2 + R5;             /* and then set shifted-in value to
                                  ** tweaked AQ.
                                  */
  r1 = r3 >> 31;
  r2 = r2 + r1;
  cc = bittst(r3,30);
  r0 = -r2;
  if !cc r0 = r2;
  SP += 4;
  (R7:5)= [SP++];                 /* Pop registers R6-R7 */
  RTS;

.Lident_return:
  CC = R1 == 0;                   /* check for divide by zero  => 0x7fffffff */
  R2 = -1 (X);
  R2 >>= 1;
  IF CC JUMP .Ltrue_ident_return;

  CC = R0 == R1;                  /* check for identical operands => 1 */
  R2 = 1 (Z);
  IF CC JUMP .Ltrue_ident_return;

  R2 = R0;                        /* assume divide by 1 => numerator */
  /*FALLTHRU*/

.Ltrue_ident_return:
  R0 = R2;                        /* Return an identity value */
  R2 = -R2;
  CC = bittst(R3,30);
  IF CC R0 = R2;
.Lzero_return:
  RTS;                            /* ...including zero */

.Lpower_of_two:
  /* Y has a single bit set, which means it's a power of two.
  ** That means we can perform the division just by shifting
  ** X to the right the appropriate number of bits
  */

  /* signbits returns the number of sign bits, minus one.
  ** 1=>30, 2=>29, ..., 0x40000000=>0. Which means we need
  ** to shift right n-signbits spaces. It also means 0x80000000
  ** is a special case, because that *also* gives a signbits of 0
  */

  R2 = R0 >> 31;
  CC = R1 < 0;
  IF CC JUMP .Ltrue_ident_return;

  R1.l = SIGNBITS R1;
  R1 = R1.L (Z);
  R1 += -30;
  R0 = LSHIFT R0 by R1.L;
  r1 = r3 >> 31;
  r0 = r0 + r1;
  R2 = -R0;                       // negate result if necessary
  CC = bittst(R3,30);
  IF CC R0 = R2;
  RTS;

.Lret_zero:
  R0 = 0;
  RTS;

.size ___divsi3, .-___divsi3
Commit	Line	Data
1394f032	1	/*
96f1050d	2	* Copyright 2004-2009 Analog Devices Inc.
1394f032	3	*
de450838	4	* Licensed under the Clear BSD license or the GPL-2 (or later)
96f1050d RG	5	*
96f1050d RG	6	* 16 / 32 bit signed division.
1394f032 BW	7	* Special cases :
	8	* 1) If(numerator == 0)
	9	* return 0
	10	* 2) If(denominator ==0)
	11	* return positive max = 0x7fffffff
	12	* 3) If(numerator == denominator)
	13	* return 1
	14	* 4) If(denominator ==1)
	15	* return numerator
	16	* 5) If(denominator == -1)
	17	* return -numerator
	18	*
	19	* Operand : R0 - Numerator (i)
	20	* R1 - Denominator (i)
	21	* R0 - Quotient (o)
	22	* Registers Used : R2-R7,P0-P2
	23	*
1394f032 BW	24	*/
	25
	26	.global ___divsi3;
51be24c3	27	.type ___divsi3, STT_FUNC;
1394f032 BW	28
	29	#ifdef CONFIG_ARITHMETIC_OPS_L1
	30	.section .l1.text
	31	#else
	32	.text
	33	#endif
	34
	35	.align 2;
	36	___divsi3 :
	37
	38
	39	R3 = R0 ^ R1;
	40	R0 = ABS R0;
	41
	42	CC = V;
	43
	44	r3 = rot r3 by -1;
	45	r1 = abs r1; /* now both positive, r3.30 means "negate result",
	46	** r3.31 means overflow, add one to result
	47	*/
	48	cc = r0 < r1;
	49	if cc jump .Lret_zero;
	50	r2 = r1 >> 15;
	51	cc = r2;
	52	if cc jump .Lidents;
	53	r2 = r1 << 16;
	54	cc = r2 <= r0;
	55	if cc jump .Lidents;
	56
	57	DIVS(R0, R1);
	58	DIVQ(R0, R1);
	59	DIVQ(R0, R1);
	60	DIVQ(R0, R1);
	61	DIVQ(R0, R1);
	62	DIVQ(R0, R1);
	63	DIVQ(R0, R1);
	64	DIVQ(R0, R1);
	65	DIVQ(R0, R1);
	66	DIVQ(R0, R1);
	67	DIVQ(R0, R1);
	68	DIVQ(R0, R1);
	69	DIVQ(R0, R1);
	70	DIVQ(R0, R1);
	71	DIVQ(R0, R1);
	72	DIVQ(R0, R1);
	73	DIVQ(R0, R1);
	74
	75	R0 = R0.L (Z);
	76	r1 = r3 >> 31; /* add overflow issue back in */
	77	r0 = r0 + r1;
	78	r1 = -r0;
	79	cc = bittst(r3, 30);
	80	if cc r0 = r1;
	81	RTS;
	82
	83	/* Can't use the primitives. Test common identities.
	84	** If the identity is true, return the value in R2.
	85	*/
	86
	87	.Lidents:
	88	CC = R1 == 0; /* check for divide by zero */
	89	IF CC JUMP .Lident_return;
	90
	91	CC = R0 == 0; /* check for division of zero */
92	IF CC JUMP .Lzero_return;
93
94	CC = R0 == R1; /* check for identical operands */
95	IF CC JUMP .Lident_return;
96
97	CC = R1 == 1; /* check for divide by 1 */
98	IF CC JUMP .Lident_return;
99
100	R2.L = ONES R1;
101	R2 = R2.L (Z);
102	CC = R2 == 1;
103	IF CC JUMP .Lpower_of_two;
104
105	/* Identities haven't helped either.
106	** Perform the full division process.
107	*/
108
109	P1 = 31; /* Set loop counter */
110
111	[--SP] = (R7:5); /* Push registers R5-R7 */
112	R2 = -R1;
113	[--SP] = R2;
114	R2 = R0 << 1; /* R2 lsw of dividend */
115	R6 = R0 ^ R1; /* Get sign */
116	R5 = R6 >> 31; /* Shift sign to LSB */
117
118	R0 = 0 ; /* Clear msw partial remainder */
119	R2 = R2 \| R5; /* Shift quotient bit */
120	R6 = R0 ^ R1; /* Get new quotient bit */
121
122	LSETUP(.Llst,.Llend) LC0 = P1; /* Setup loop */
123	.Llst: R7 = R2 >> 31; /* record copy of carry from R2 */
124	R2 = R2 << 1; /* Shift 64 bit dividend up by 1 bit */
125	R0 = R0 << 1 \|\| R5 = [SP];
126	R0 = R0 \| R7; /* and add carry */
127	CC = R6 < 0; /* Check quotient(AQ) */
128	/* we might be subtracting divisor (AQ==0) */
129	IF CC R5 = R1; /* or we might be adding divisor (AQ==1)*/
130	R0 = R0 + R5; /* do add or subtract, as indicated by AQ */
131	R6 = R0 ^ R1; /* Generate next quotient bit */
132	R5 = R6 >> 31;
133	/* Assume AQ==1, shift in zero */
134	BITTGL(R5,0); /* tweak AQ to be what we want to shift in */
135	.Llend: R2 = R2 + R5; /* and then set shifted-in value to
136	** tweaked AQ.
137	*/
138	r1 = r3 >> 31;
139	r2 = r2 + r1;
140	cc = bittst(r3,30);
141	r0 = -r2;
142	if !cc r0 = r2;
143	SP += 4;
144	(R7:5)= [SP++]; /* Pop registers R6-R7 */
145	RTS;
146
147	.Lident_return:
148	CC = R1 == 0; /* check for divide by zero => 0x7fffffff */
149	R2 = -1 (X);
150	R2 >>= 1;
151	IF CC JUMP .Ltrue_ident_return;
152
153	CC = R0 == R1; /* check for identical operands => 1 */
154	R2 = 1 (Z);
155	IF CC JUMP .Ltrue_ident_return;
156
157	R2 = R0; /* assume divide by 1 => numerator */
158	/FALLTHRU/
159
160	.Ltrue_ident_return:
161	R0 = R2; /* Return an identity value */
162	R2 = -R2;
163	CC = bittst(R3,30);
164	IF CC R0 = R2;
165	.Lzero_return:
166	RTS; /* ...including zero */
167
168	.Lpower_of_two:
169	/* Y has a single bit set, which means it's a power of two.
170	** That means we can perform the division just by shifting
171	** X to the right the appropriate number of bits
172	*/
173
174	/* signbits returns the number of sign bits, minus one.
175	** 1=>30, 2=>29, ..., 0x40000000=>0. Which means we need
176	** to shift right n-signbits spaces. It also means 0x80000000
177	** is a special case, because that also gives a signbits of 0
178	*/
179
180	R2 = R0 >> 31;
181	CC = R1 < 0;
182	IF CC JUMP .Ltrue_ident_return;
183
184	R1.l = SIGNBITS R1;
185	R1 = R1.L (Z);
186	R1 += -30;
187	R0 = LSHIFT R0 by R1.L;
188	r1 = r3 >> 31;
189	r0 = r0 + r1;
190	R2 = -R0; // negate result if necessary
191	CC = bittst(R3,30);
192	IF CC R0 = R2;
193	RTS;
194
195	.Lret_zero:
196	R0 = 0;
197	RTS;
51be24c3 MF	198
51be24c3 MF	199	.size ___divsi3, .-___divsi3