root/arch/microblaze/lib/modsi3.S

   1 /* SPDX-License-Identifier: GPL-2.0 */
   2 #include <linux/linkage.h>
   3 
   4 /*
   5 * modulo operation for 32 bit integers.
   6 *       Input : op1 in Reg r5
   7 *               op2 in Reg r6
   8 *       Output: op1 mod op2 in Reg r3
   9 */
  10 
  11         .text
  12         .globl  __modsi3
  13         .type __modsi3,  @function
  14         .ent __modsi3
  15 
  16 __modsi3:
  17         .frame  r1, 0, r15
  18 
  19         addik   r1, r1, -16
  20         swi     r28, r1, 0
  21         swi     r29, r1, 4
  22         swi     r30, r1, 8
  23         swi     r31, r1, 12
  24 
  25         beqi    r6, div_by_zero /* div_by_zero division error */
  26         beqi    r5, result_is_zero /* result is zero */
  27         bgeid   r5, r5_pos
  28         /* get the sign of the result [ depends only on the first arg] */
  29         add     r28, r5, r0
  30         rsubi   r5, r5, 0        /* make r5 positive */
  31 r5_pos:
  32         bgei    r6, r6_pos
  33         rsubi   r6, r6, 0        /* make r6 positive */
  34 r6_pos:
  35         addik   r3, r0, 0 /* clear mod */
  36         addik   r30, r0, 0 /* clear div */
  37         addik   r29, r0, 32 /* initialize the loop count */
  38 /* first part try to find the first '1' in the r5 */
  39 div1:
  40         add     r5, r5, r5 /* left shift logical r5 */
  41         bgeid   r5, div1
  42         addik   r29, r29, -1
  43 div2:
  44         /* left shift logical r5 get the '1' into the carry */
  45         add     r5, r5, r5
  46         addc    r3, r3, r3 /* move that bit into the mod register */
  47         rsub    r31, r6, r3 /* try to subtract (r30 a r6) */
  48         blti    r31, mod_too_small
  49         /* move the r31 to mod since the result was positive */
  50         or      r3, r0, r31
  51         addik   r30, r30, 1
  52 mod_too_small:
  53         addik   r29, r29, -1
  54         beqi    r29, loop_end
  55         add     r30, r30, r30 /* shift in the '1' into div */
  56         bri     div2 /* div2 */
  57 loop_end:
  58         bgei    r28, return_here
  59         brid    return_here
  60         rsubi   r3, r3, 0 /* negate the result */
  61 div_by_zero:
  62 result_is_zero:
  63         or      r3, r0, r0 /* set result to 0 [both mod as well as div are 0] */
  64 return_here:
  65 /* restore values of csrs and that of r3 and the divisor and the dividend */
  66         lwi     r28, r1, 0
  67         lwi     r29, r1, 4
  68         lwi     r30, r1, 8
  69         lwi     r31, r1, 12
  70         rtsd    r15, 8
  71         addik   r1, r1, 16
  72 
  73 .size __modsi3,  . - __modsi3
  74 .end __modsi3