Karl Zweimüller / LcdWindow

Fork of LCD-Window which works with Enhanced TextLCD from Wim

Fork of LcdWindow by Hendrik Lipka

semaphore.cpp@10:d40c70908bf0, 2016-01-04 (annotated)

Committer:
charly
Date:
Mon Jan 04 20:22:17 2016 +0000
Revision:
10:d40c70908bf0
Parent:
9:2fe93daa2106 
Adapted for EnhancedLCD. Disabled semaphore as there are problem with new mbed-library.

Who changed what in which revision?

UserRevisionLine numberNew contents of line
hlipka 3:e5d5e2fe4bf6 1 /**
hlipka 3:e5d5e2fe4bf6 2 * code from Igor Skochinsky
hlipka 3:e5d5e2fe4bf6 3 * taken from http://mbed.org/forum/mbed/post/799/
hlipka 3:e5d5e2fe4bf6 4 */
hlipka 3:e5d5e2fe4bf6 5
hlipka 3:e5d5e2fe4bf6 6 #include "semaphore.h"
hlipka 3:e5d5e2fe4bf6 7
hlipka 9:2fe93daa2106 8 Semaphore::Semaphore(): s(SemFree) {};
hlipka 9:2fe93daa2106 9 bool Semaphore::_abort=false;
hlipka 9:2fe93daa2106 10
hlipka 9:2fe93daa2106 11 bool Semaphore::take(bool block) {
hlipka 9:2fe93daa2106 12 if (_abort)
hlipka 9:2fe93daa2106 13 block=false;
hlipka 3:e5d5e2fe4bf6 14 int oldval;
charly 10:d40c70908bf0 15 /*
hlipka 3:e5d5e2fe4bf6 16 #if defined(TARGET_LPC1768) // on Cortex-M3 we can use ldrex/strex
hlipka 3:e5d5e2fe4bf6 17 do {
hlipka 9:2fe93daa2106 18 // read the semaphore value
hlipka 9:2fe93daa2106 19 oldval = __ldrex(&s);
hlipka 9:2fe93daa2106 20 // loop again if it is locked and we are blocking
hlipka 9:2fe93daa2106 21 // or setting it with strex failed
hlipka 9:2fe93daa2106 22 } while ( (block && oldval == SemTaken) || __strex(SemTaken, &s) != 0 );
hlipka 3:e5d5e2fe4bf6 23 if ( !block ) __clrex(); // clear exclusive lock set by ldrex
hlipka 3:e5d5e2fe4bf6 24 #else // on arm7 there's only swp
charly 10:d40c70908bf0 25
hlipka 3:e5d5e2fe4bf6 26 do {
hlipka 9:2fe93daa2106 27 // swp sets the pointed data to the given value and returns the previous one
hlipka 9:2fe93daa2106 28 oldval = __swp(SemTaken, &s);
hlipka 9:2fe93daa2106 29 // if blocking, loop until the previous value becomes 0
hlipka 9:2fe93daa2106 30 // which would mean we have successfully taken the lock
hlipka 9:2fe93daa2106 31 } while (block && oldval == SemTaken);
charly 10:d40c70908bf0 32 //#endif
charly 10:d40c70908bf0 33
hlipka 3:e5d5e2fe4bf6 34 return oldval == SemFree;
charly 10:d40c70908bf0 35 */
charly 10:d40c70908bf0 36 return true;
hlipka 9:2fe93daa2106 37 }
hlipka 9:2fe93daa2106 38
hlipka 9:2fe93daa2106 39 // release the semaphore
hlipka 9:2fe93daa2106 40 void Semaphore::release() {
hlipka 3:e5d5e2fe4bf6 41 s = SemFree;
hlipka 9:2fe93daa2106 42 }