Eric Lee / smarc-fsl-linux-kernel

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arch/microblaze/lib/udivsi3.S 1.87 KB
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4e07dba7c   Michal Simek   microblaze: Add l... 
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  #include <linux/linkage.h>
  
  /*
  * Unsigned divide operation.
  *	Input :	Divisor in Reg r5
  *		Dividend in Reg r6
  *	Output: Result in Reg r3
  */
  
  	.text
  	.globl	__udivsi3
  	.type __udivsi3, @function
  	.ent __udivsi3
  
  __udivsi3:
  
  	.frame	r1, 0, r15
  
  	addik	r1, r1, -12
  	swi	r29, r1, 0
  	swi	r30, r1, 4
  	swi	r31, r1, 8
  
  	beqi	r6, div_by_zero /* div_by_zero /* division error */
  	beqid	r5, result_is_zero /* result is zero */
  	addik	r30, r0, 0 /* clear mod */
  	addik	r29, r0, 32 /* initialize the loop count */
  
  /* check if r6 and r5 are equal - if yes, return 1 */
  	rsub	r18, r5, r6
  	beqid	r18, return_here
  	addik	r3, r0, 1
  
  /* check if (uns)r6 is greater than (uns)r5. in that case, just return 0 */
  	xor	r18, r5, r6
  	bgeid	r18, 16
  	add	r3, r0, r0 /* we would anyways clear r3 */
  	blti	r6, return_here /* r6[bit 31 = 1] hence is greater */
  	bri	checkr6
  	rsub	r18, r6, r5 /* microblazecmp */
  	blti	r18, return_here
  
  /* if r6 [bit 31] is set, then return result as 1 */
  checkr6:
  	bgti	r6, div0
  	brid	return_here
  	addik	r3, r0, 1
  
  /* first part try to find the first '1' in the r5 */
  div0:
  	blti	r5, div2
  div1:
  	add	r5, r5, r5 /* left shift logical r5 */
  	bgtid	r5, div1
  	addik	r29, r29, -1
  div2:
  /* left shift logical r5 get the '1' into the carry */
  	add	r5, r5, r5
  	addc	r30, r30, r30 /* move that bit into the mod register */
  	rsub	r31, r6, r30 /* try to subtract (r30 a r6) */
  	blti	r31, mod_too_small
  /* move the r31 to mod since the result was positive */
  	or	r30, r0, r31
  	addik	r3, r3, 1
  mod_too_small:
  	addik	r29, r29, -1
  	beqi	r29, loop_end
  	add	r3, r3, r3 /* shift in the '1' into div */
  	bri	div2 /* div2 */
  loop_end:
  	bri	return_here
  div_by_zero:
  result_is_zero:
  	or	r3, r0, r0 /* set result to 0 */
  return_here:
  /* restore values of csrs and that of r3 and the divisor and the dividend */
  	lwi	r29, r1, 0
  	lwi	r30, r1, 4
  	lwi	r31, r1, 8
  	rtsd	r15, 8
  	addik	r1, r1, 12
  
  .size __udivsi3, . - __udivsi3
  .end __udivsi3