X-Git-Url: https://git.ucc.asn.au/?a=blobdiff_plain;f=Kernel%2Farch%2Fx86%2Finclude%2Farch.h;h=0fec144e65bc7ef77c0d9c8656c55a07d5c09d8f;hb=15999a03acd4083fb2618c92bebbc557813c5084;hp=67a629016f6839576c7bbf30fb921dffa5decacb;hpb=7d881c2e5fef91a6570e46ef69a5d4a5cf0e8b4d;p=tpg%2Facess2.git

diff --git a/Kernel/arch/x86/include/arch.h b/Kernel/arch/x86/include/arch.h
index 67a62901..0fec144e 100644
--- a/Kernel/arch/x86/include/arch.h
+++ b/Kernel/arch/x86/include/arch.h
@@ -29,47 +29,70 @@
 
 #define __ASM__	__asm__ __volatile__
 
-#define LONGLOCK_NUM_THREADS	8
-
-// === MACROS ===
+// === Spinlocks ===
+/**
+ * \brief Short Spinlock structure
+ */
 struct sShortSpinlock {
-	volatile int	Lock;
-	 int	IF;
+	volatile int	Lock;	//!< Lock value
+	 int	IF;	//!< Interrupt state on call to SHORTLOCK
 };
 /**
  * \brief Determine if a short spinlock is locked
+ * \param Lock	Lock pointer
  */
 static inline int IS_LOCKED(struct sShortSpinlock *Lock) {
 	return !!Lock->Lock;
 }
 /**
  * \brief Acquire a Short Spinlock
- * \note Stops interrupts, so be careful
+ * \param Lock	Lock pointer
+ * 
+ * This type of mutex should only be used for very short sections of code,
+ * or in places where a Mutex_* would be overkill, such as appending
+ * an element to linked list (usually two assignement lines in C)
+ * 
+ * \note This type of lock halts interrupts, so ensure that no timing
+ * functions are called while it is held.
  */
 static inline void SHORTLOCK(struct sShortSpinlock *Lock) {
 	 int	v = 1;
-	__ASM__ ("pushf;\n\tpop %%eax" : "=a"(Lock->IF));
-	Lock->IF &= 0x200;
-	__ASM__ ("cli");	// Stop task switches
+	 int	IF;
+	// int	val = GetCPUNum() + 1;
+	
+	// Save interrupt state and clear interrupts
+	__ASM__ ("pushf;\n\tcli;\n\tpop %%eax" : "=a"(IF));
+	IF &= 0x200;
+	
 	// Wait for another CPU to release
 	while(v)
-		__ASM__("xchgl %%eax, (%%edi)":"=a"(v):"a"(1),"D"(&Lock->Lock));
+		__ASM__("xchgl %%ecx, (%%edi)":"=c"(v):"a"(1),"D"(&Lock->Lock));
+	
+	Lock->IF = IF;
 }
 /**
  * \brief Release a short lock
+ * \param Lock	Lock pointer
  */
 static inline void SHORTREL(struct sShortSpinlock *Lock) {
-	Lock->Lock = 0;
-	#if 0
-	__ASM__ ("pushf;\n\tor %0, (%%esp);\n\tpopf" : : "a"(Lock->IF));
-	#else
-	if(Lock->IF)	__ASM__ ("sti");
-	#endif
+	// Lock->IF can change anytime once Lock->Lock is zeroed
+	if(Lock->IF) {
+		Lock->Lock = 0;
+		__ASM__ ("sti");
+	}
+	else {
+		Lock->Lock = 0;
+	}
 }
+
+// === MACROS ===
 /**
  * \brief Halt the CPU
  */
 #define	HALT()	__asm__ __volatile__ ("hlt")
+/**
+ * \brief Fire a magic breakpoint (bochs)
+ */
 #define	MAGIC_BREAK()	__asm__ __volatile__ ("xchg %bx, %bx")
 
 // === TYPES ===