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// TITLE("Large Integer Arithmetic")
//++
//
// Copyright (c) 1990 Microsoft Corporation
//
// Module Name:
//
// largeint.s
//
// Abstract:
//
// This module implements __int64 arithmetic helper routines for the MIPS Compiler.
//
//
// Author:
//
// David N. Cutler (davec) 18-Apr-1990
//
// Environment:
//
// Any mode.
//
// Revision History:
//
// This module is derived from largeint.s in ntos\rtl\mips\largeint.s
//
//--
#include "ksmips.h"
SBTTL("int64 Shift Left")
//++
//
// LARGE_INTEGER
// RtlLargeIntegerShiftLeft (
// IN LARGE_INTEGER LargeInteger,
// IN CCHAR ShiftCount
// )
//
// Routine Description:
//
// This function shifts a signed large integer left by an unsigned
// integer modulo 64 and returns the shifted signed large integer
// result.
//
// N.B. No test is made for significant bits shifted out of the result.
//
// Arguments:
//
// LargeInteger (a0=LSW, a1=MSW) - Supplies the large integer to be shifted.
//
// ShiftCount (a2) - bits to shift
//
// Return Value:
//
// The large integer result is stored into (v0=LSW,v1=MSW).
//
//--
LEAF_ENTRY(__ll_lshift)
and a2,a2,0x3f // truncate shift count mod 64
//
// Left shift the operand by the specified shift count.
//
li t1,32 // compute right shift count
subu t1,t1,a2 //
bgtz t1,10f // if gtz, shift less that 32-bits
//
// Shift count is greater than or equal 32 bits - low half of result is zero,
// high half is the low half shifted left by remaining count.
//
sll v1,a0,a2 // set high half of result
move v0,zero // store low part of reuslt
j ra // return
//
// Shift count is less than 32-bits - high half of result is the high half
// of operand shifted left by count combined with the low half of the operand
// shifted right, low half of result is the low half shifted left.
//
10: move v0,a0 // set low half of result
sll v1,a1,a2 // shift high half left count bits
beq zero,a2,20f // if eq, no more shifts necessary
srl t0,v0,t1 // isolate shifted out bits of low half
sll v0,v0,a2 // shift low half left count bits
or v1,v1,t0 // combine bits for high half of result
20: j ra // return
.end __ll_rshift
SBTTL("int64 Logical Shift Right")
//++
//
// LARGE_INTEGER
// RtlLargeIntegerShiftRight (
// IN LARGE_INTEGER LargeInteger,
// IN CCHAR ShiftCount
// )
//
// Routine Description:
//
// This function shifts an unsigned large integer right by an unsigned
// integer modulo 64 and returns the shifted unsigned large integer
// result.
//
// Arguments:
//
// LargeInteger (a0=LSW, a1=MSW) - Supplies the large integer to be shifted.
//
// ShiftCount (a2) - Supplies the right shift count.
//
// Return Value:
//
// The large integer result is stored into (v0=LSW,v1=MSW).
//
//--
LEAF_ENTRY(__ull_rshift)
and a2,a2,0x3f // truncate shift count mod 64
//
// Right shift the operand by the specified shift count.
//
li t1,32 // compute left shift count
subu t1,t1,a2 //
bgtz t1,10f // if gtz, shift less that 32-bits
//
// Shift count is greater than or equal 32 bits - high half of result is
// zero, low half is the high half shifted right by remaining count.
//
srl v0,a1,a2 // set low half of result
move v1,zero // store high part of result
j ra // return
//
// Shift count is less than 32-bits - high half of result is the high half
// of operand shifted right by count, low half of result is the shifted out
// bits of the high half combined with the right shifted low half of the
// operand.
//
10: move v1,a1 // set high half of result
srl v0,a0,a2 // shift low half right count bits
beq zero,a2,20f // if eq, no more shifts necessary
sll t0,a1,t1 // isolate shifted out bits of high half
srl v1,a1,a2 // shift high half right count bits
or v0,v0,t0 // combine bits for low half of result
20: j ra // return
.end __ull_rshift
SBTTL("int64 Arithmetic Shift Right")
//++
//
// LARGE_INTEGER
// RtlLargeIntegerArithmeticShift (
// IN LARGE_INTEGER LargeInteger,
// IN CCHAR ShiftCount
// )
//
// Routine Description:
//
// This function shifts a signed large integer right by an unsigned
// integer modulo 64 and returns the shifted signed large integer
// result.
//
// Arguments:
//
// LargeInteger (a0=LSW, a1=MSW) - Supplies the large integer to be shifted.
//
// ShiftCount (a2) - Supplies the right shift count.
//
// Return Value:
//
// The large integer result is stored into (v0=LSW,v1=MSW).
//
//--
LEAF_ENTRY(__ll_rshift)
and a2,a2,0x3f // truncate shift count mod 64
//
// Right shift the operand by the specified shift count.
//
li t1,32 // compute left shift count
subu t1,t1,a2 //
bgtz t1,10f // if gtz, shift less that 32-bits
//
// Shift count is greater than or equal 32 bits - high half of result is
// bit63 sign-extended, low half is the high half shifted right by remaining count.
//
sra v0,a1,a2 // set low half of result
sra v1,a1,31 // set high half of result
j ra // return
//
// Shift count is less than 32-bits - high half of result is the high half
// of operand shifted right by count, low half of result is the shifted out
// bits of the high half combined with the right shifted low half of the
// operand.
//
10: move v1, a1 // set high half of result
srl v0,a0,a2 // shift low half right count bits
beq zero,a2,20f // if eq, no more shifts necessary
sll t0,a1,t1 // isolate shifted out bits of high half
sra v1,a1,a2 // shift high half right count bits
or v0,v0,t0 // combine bits for low half of result
20: j ra // return
.end __ll_rshift
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