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//// Copyright (c) 1995 Microsoft Corporation//// Module Name://// atomic.s// // Abstract:// // This module implements atomic operations such as InterlockedOr,// InterlockedAnd and the MrswFetch...() functions used for// Multiple Reader Single Writer (mrsw) synchronization.// // Author:// // Dave Hastings (daveh) creation-date 05-Jan-1996// from ..\mips\atomic.s// // Notes://// Mrsw Counter is: WriterCount : 16// ReaderCount : 16// // Revision History:
#include "kxalpha.h"
SBTTL("MrswFetchAndIncrementWriter")//++//// MRSWCOUNTERS// MrswFetchAndIncrementWriter(// PMRSWCOUNTERS pCounters// )//// Routine Description://// Atomically increment Writer counter and return the new reader/writer// counts (the values AFTER the increment).//// Arguments://// pCounters (a0) - pointer to reader/writer counters//// Return Value://// MRSWCOUNTERS - value of both counters AFTER writer count was incremented////-- LEAF_ENTRY(MrswFetchAndIncrementWriter) PROLOGUE_END
//// Increment the writer count and load both reader and writer accounts// atomically.//fiw10: ldl_l v0, (a0) // Get both reader and write counts addl v0, 1, v0 // increment the writer count bis v0, zero, t0 stl_c t0, (a0) beq t0, fiw20 // atomic update failed? mb // insure that updates of the data // being protected are synch'ed ret zero, (ra) fiw20: br zero, fiw10 .end MrswFetchAndIncrementWriter
//++//// MRSWCOUNTERS// MrswFetchAndIncrementReader(// PMRSWCOUNTERS pCounters// )//// Routine Description://// Atomically: Get WriterCount. If WriterCount zero, increment ReaderCount// and return the value AFTER the increment. Else, return right away.//// Arguments://// pCounters (a0) - pointer to reader/writer counters//// Return Value://// MRSWCOUNTERS////-- LEAF_ENTRY(MrswFetchAndIncrementReader) PROLOGUE_END
//// Increment the waiting reader count and load both reader and writer accounts// atomically.//fir10: ldah t2, 1(zero) // Load increment value for Reader count ldl_l v0, (a0) // get both counters and v0, 0xffff, t1 // isolate writer count bne t1, fir20 // exit if there is already a writer addl v0, t2, v0 // increment reader count bis v0, zero, t0 stl_c t0, (a0) beq t0, fir30 mb // insure that updates of the data // being protected are synch'ed fir20: ret zero, (ra)
fir30: br zero, fir10 .end MrswFetchAndIncrementReader
SBTTL("MrswFetchAndDecrementWriter")//++//// MRSWCOUNTERS// MrswFetchAndDecrementWriter(// PMRSWCOUNTERS pCounters// )//// Routine Description://// Atomically decrement Writer counter and return the new reader/writer// counts (the values AFTER the decrement).//// Arguments://// pCounters (a0) - pointer to reader/writer counters//// Return Value://// MRSWCOUNTERS - value of both counters AFTER writer count was decremented////-- LEAF_ENTRY(MrswFetchAndDecrementWriter) PROLOGUE_END
mb // insure that updates of the data // being protected are synch'ed//// Decrement the writer count and load both reader and writer accounts// atomically.//fdw10: ldl_l v0, (a0) // get both counters subl v0, 1, v0 // decrement writer count bis v0, zero, t0 stl_c t0, (a0) beq t0, fdw20 ret zero, (ra) fdw20: br zero, fdw10 .end MrswFetchAndDecrementWriter
//++//// MRSWCOUNTERS// MrswFetchAndDecrementReader(// PMRSWCOUNTERS pCounters// )//// Routine Description://// Atomically decrement Active Reader counter and return the new reader/writer// counts (the values AFTER the decrement).//// Arguments://// pCounters (a0) - pointer to reader/writer counters//// Return Value://// MRSWCOUNTERS - value of both counters AFTER writer count was decremented////// Notes://// No MB is used, because the readers don't write into the data, and this// function is called when a thread is DONE reading////-- LEAF_ENTRY(MrswFetchAndDecrementReader) PROLOGUE_END
//// Decrement the active reader count and load both reader and writer accounts// atomically.//fdr10: ldah t1, 1(zero) // decrement value to dec reader count ldl_l v0, (a0) // get both counters subl v0, t1, v0 bis v0, zero, t0 stl_c t0, (a0) beq t0, fdr20 ret zero, (ra) fdr20: br zero, fdr10 .end MrswFetchAndDecrementReader //++//// DWORD// InterlockedAnd(// DWORD *pDWORD, // ptr to DWORD to bitwise AND a value into// DWORD AndValue // value to bitwise OR into *pDWORD// )//// Routine Description://// Atomically grabs the value of *pDWORD and clears the bits in *pDWORD// specified by Mask. ie. implements atomically: temp = *pDWORD;
// *pDWORD &= Mask;
// return temp;
//// Arguments://// pDWORD - ptr to DWORD to modify// Mask - value to bitwise AND into *pDWORD//// Return Value://// Value of *pDWORD before the AND operation.////-- LEAF_ENTRY(InterlockedAnd) PROLOGUE_END ia10: ldl_l v0, (a0) and v0, a1, t0 stl_c t0, (a0) beq t0, ia20 ret zero, (ra) ia20: br zero, ia10 .end InterlockedAnd
//++//// DWORD// InterlockedOr(// DWORD *pDWORD, // ptr to DWORD to bitwise OR a value into// DWORD OrValue // value to bitwise OR into *pDWORD// )//// Routine Description://// Atomically grabs the value of *pDWORD and bitwise ORs in OrValue.//// Arguments://// pDWORD - ptr to DWORD to modify// OrValue - value to bitwise OR into *pDWORD//// Return Value://// Value of *pDWORD before the OR operation.////-- LEAF_ENTRY(InterlockedOr) PROLOGUE_END
io10: ldl_l v0, (a0) bis v0, a1, t0 stl_c t0, (a0) beq t0, io20 ret zero, (ra) io20: br zero, io10 .end InterlockedOr
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