LXR linux/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 */
  31r5_pos:
  32        bgei    r6, r6_pos
  33        rsubi   r6, r6, 0        /* make r6 positive */
  34r6_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 */
  39div1:
  40        add     r5, r5, r5 /* left shift logical r5 */
  41        bgeid   r5, div1
  42        addik   r29, r29, -1
  43div2:
  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
  52mod_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 */
  57loop_end:
  58        bgei    r28, return_here
  59        brid    return_here
  60        rsubi   r3, r3, 0 /* negate the result */
  61div_by_zero:
  62result_is_zero:
  63        or      r3, r0, r0 /* set result to 0 [both mod as well as div are 0] */
  64return_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
  75