xref: /openbsd/gnu/llvm/compiler-rt/lib/builtins/hexagon/udivdi3.S (revision 3cab2bb3)

//===----------------------Hexagon builtin routine ------------------------===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//


	.macro FUNCTION_BEGIN name
	.text
        .p2align 5
	.globl \name
	.type  \name, @function
\name:
	.endm

	.macro FUNCTION_END name
	.size  \name, . - \name
	.endm


FUNCTION_BEGIN __hexagon_udivdi3
	{
		r6 = cl0(r1:0)              // count leading 0's of dividend (numerator)
		r7 = cl0(r3:2)              // count leading 0's of divisor (denominator)
		r5:4 = r3:2                 // divisor moved into working registers
		r3:2 = r1:0                 // dividend is the initial remainder, r3:2 contains remainder
	}
	{
		r10 = sub(r7,r6)            // left shift count for bit & divisor
		r1:0 = #0                   // initialize quotient to 0
		r15:14 = #1                 // initialize bit to 1
	}
	{
		r11 = add(r10,#1)           // loop count is 1 more than shift count
		r13:12 = lsl(r5:4,r10)      // shift divisor msb into same bit position as dividend msb
		r15:14 = lsl(r15:14,r10)    // shift the bit left by same amount as divisor
	}
	{
		p0 = cmp.gtu(r5:4,r3:2)     // check if divisor > dividend
		loop0(1f,r11)               // register loop
	}
	{
		if (p0) jumpr r31           // if divisor > dividend, we're done, so return
	}
	.falign
1:
	{
		p0 = cmp.gtu(r13:12,r3:2)   // set predicate reg if shifted divisor > current remainder
	}
	{
		r7:6 = sub(r3:2, r13:12)    // subtract shifted divisor from current remainder
		r9:8 = add(r1:0, r15:14)    // save current quotient to temp (r9:8)
	}
	{
		r1:0 = vmux(p0, r1:0, r9:8) // choose either current quotient or new quotient (r9:8)
		r3:2 = vmux(p0, r3:2, r7:6) // choose either current remainder or new remainder (r7:6)
	}
	{
		r15:14 = lsr(r15:14, #1)    // shift bit right by 1 for next iteration
		r13:12 = lsr(r13:12, #1)    // shift "shifted divisor" right by 1 for next iteration
	}:endloop0
	{
		jumpr r31                   // return
	}
FUNCTION_END __hexagon_udivdi3

  .globl __qdsp_udivdi3
  .set   __qdsp_udivdi3, __hexagon_udivdi3