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Merge pull request #2054 from geky/critical-cas-ptr 

Added cas instrinsics for pointer values
pull/2051/head
Sam Grove 2016-07-07 16:59:56 -05:00 committed by GitHub
parent 0bc7622126 946199183c
commit c55c07a890
2 changed files with 123 additions and 35 deletions
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107
hal/api/critical.h
View File

@ -19,6 +19,8 @@
#define __MBED_UTIL_CRITICAL_H__ #define __MBED_UTIL_CRITICAL_H__
#include <stdbool.h> #include <stdbool.h>
#include <stdint.h>
#include <stddef.h>
#ifdef __cplusplus #ifdef __cplusplus
extern "C" { extern "C" {
@ -47,7 +49,7 @@ bool core_util_are_interrupts_enabled(void);
* section) will be preserved on exit from the section. * section) will be preserved on exit from the section.
* 4) This implementation will currently only work on code running in privileged mode. * 4) This implementation will currently only work on code running in privileged mode.
*/ */
void core_util_critical_section_enter(); void core_util_critical_section_enter(void);
/** Mark the end of a critical section /** Mark the end of a critical section
* *
@ -60,7 +62,7 @@ void core_util_critical_section_enter();
* section) will be preserved on exit from the section. * section) will be preserved on exit from the section.
* 4) This implementation will currently only work on code running in privileged mode. * 4) This implementation will currently only work on code running in privileged mode.
*/ */
void core_util_critical_section_exit(); void core_util_critical_section_exit(void);
/** /**
* Atomic compare and set. It compares the contents of a memory location to a * Atomic compare and set. It compares the contents of a memory location to a
@ -106,7 +108,7 @@ void core_util_critical_section_exit();
* *
* function incr(p : pointer to int, a : int) returns int { * function incr(p : pointer to int, a : int) returns int {
* done = false * done = false
* *value = *p // This fetch operation need not be atomic. * value = *p // This fetch operation need not be atomic.
* while not done { * while not done {
* done = atomic_cas(p, &value, value + a) // *value gets updated automatically until success * done = atomic_cas(p, &value, value + a) // *value gets updated automatically until success
* } * }
@ -159,7 +161,7 @@ bool core_util_atomic_cas_u8(uint8_t *ptr, uint8_t *expectedCurrentValue, uint8_
* *
* function incr(p : pointer to int, a : int) returns int { * function incr(p : pointer to int, a : int) returns int {
* done = false * done = false
* *value = *p // This fetch operation need not be atomic. * value = *p // This fetch operation need not be atomic.
* while not done { * while not done {
* done = atomic_cas(p, &value, value + a) // *value gets updated automatically until success * done = atomic_cas(p, &value, value + a) // *value gets updated automatically until success
* } * }
@ -212,7 +214,7 @@ bool core_util_atomic_cas_u16(uint16_t *ptr, uint16_t *expectedCurrentValue, uin
* *
* function incr(p : pointer to int, a : int) returns int { * function incr(p : pointer to int, a : int) returns int {
* done = false * done = false
* *value = *p // This fetch operation need not be atomic. * value = *p // This fetch operation need not be atomic.
* while not done { * while not done {
* done = atomic_cas(p, &value, value + a) // *value gets updated automatically until success * done = atomic_cas(p, &value, value + a) // *value gets updated automatically until success
* } * }
@ -222,12 +224,57 @@ bool core_util_atomic_cas_u16(uint16_t *ptr, uint16_t *expectedCurrentValue, uin
bool core_util_atomic_cas_u32(uint32_t *ptr, uint32_t *expectedCurrentValue, uint32_t desiredValue); bool core_util_atomic_cas_u32(uint32_t *ptr, uint32_t *expectedCurrentValue, uint32_t desiredValue);
/** /**
* Atomic increment. * Atomic compare and set. It compares the contents of a memory location to a
* @param valuePtr Target memory location being incremented. * given value and, only if they are the same, modifies the contents of that
* @param delta The amount being incremented. * memory location to a given new value. This is done as a single atomic
* @return The new incremented value. * operation. The atomicity guarantees that the new value is calculated based on
* up-to-date information; if the value had been updated by another thread in
* the meantime, the write would fail due to a mismatched expectedCurrentValue.
*
* Refer to https://en.wikipedia.org/wiki/Compare-and-set [which may redirect
* you to the article on compare-and swap].
*
* @param ptr The target memory location.
* @param[in,out] expectedCurrentValue A pointer to some location holding the
* expected current value of the data being set atomically.
* The computed 'desiredValue' should be a function of this current value.
* @Note: This is an in-out parameter. In the
* failure case of atomic_cas (where the
* destination isn't set), the pointee of expectedCurrentValue is
* updated with the current value.
* @param[in] desiredValue The new value computed based on '*expectedCurrentValue'.
*
* @return true if the memory location was atomically
* updated with the desired value (after verifying
* that it contained the expectedCurrentValue),
* false otherwise. In the failure case,
* exepctedCurrentValue is updated with the new
* value of the target memory location.
*
* pseudocode:
* function cas(p : pointer to int, old : pointer to int, new : int) returns bool {
* if *p != *old {
* *old = *p
* return false
* }
* *p = new
* return true
* }
*
* @Note: In the failure case (where the destination isn't set), the value
* pointed to by expectedCurrentValue is still updated with the current value.
* This property helps writing concise code for the following incr:
*
* function incr(p : pointer to int, a : int) returns int {
* done = false
* value = *p // This fetch operation need not be atomic.
* while not done {
* done = atomic_cas(p, &value, value + a) // *value gets updated automatically until success
* }
* return value + a
* }
*/ */
uint8_t core_util_atomic_incr_u8(uint8_t * valuePtr, uint8_t delta); bool core_util_atomic_cas_ptr(void **ptr, void **expectedCurrentValue, void *desiredValue);
/** /**
* Atomic increment. * Atomic increment.
@ -235,7 +282,7 @@ uint8_t core_util_atomic_incr_u8(uint8_t * valuePtr, uint8_t delta);
* @param delta The amount being incremented. * @param delta The amount being incremented.
* @return The new incremented value. * @return The new incremented value.
*/ */
uint16_t core_util_atomic_incr_u16(uint16_t * valuePtr, uint16_t delta); uint8_t core_util_atomic_incr_u8(uint8_t *valuePtr, uint8_t delta);
/** /**
* Atomic increment. * Atomic increment.
@ -243,7 +290,26 @@ uint16_t core_util_atomic_incr_u16(uint16_t * valuePtr, uint16_t delta);
* @param delta The amount being incremented. * @param delta The amount being incremented.
* @return The new incremented value. * @return The new incremented value.
*/ */
uint32_t core_util_atomic_incr_u32(uint32_t * valuePtr, uint32_t delta); uint16_t core_util_atomic_incr_u16(uint16_t *valuePtr, uint16_t delta);
/**
* Atomic increment.
* @param valuePtr Target memory location being incremented.
* @param delta The amount being incremented.
* @return The new incremented value.
*/
uint32_t core_util_atomic_incr_u32(uint32_t *valuePtr, uint32_t delta);
/**
* Atomic increment.
* @param valuePtr Target memory location being incremented.
* @param delta The amount being incremented in bytes.
* @return The new incremented value.
*
* @note The type of the pointer argument is not taken into account
* and the pointer is incremented by bytes.
*/
void *core_util_atomic_incr_ptr(void **valuePtr, ptrdiff_t delta);
/** /**
* Atomic decrement. * Atomic decrement.
@ -251,7 +317,7 @@ uint32_t core_util_atomic_incr_u32(uint32_t * valuePtr, uint32_t delta);
* @param delta The amount being decremented. * @param delta The amount being decremented.
* @return The new decremented value. * @return The new decremented value.
*/ */
uint8_t core_util_atomic_decr_u8(uint8_t * valuePtr, uint8_t delta); uint8_t core_util_atomic_decr_u8(uint8_t *valuePtr, uint8_t delta);
/** /**
* Atomic decrement. * Atomic decrement.
@ -259,7 +325,7 @@ uint8_t core_util_atomic_decr_u8(uint8_t * valuePtr, uint8_t delta);
* @param delta The amount being decremented. * @param delta The amount being decremented.
* @return The new decremented value. * @return The new decremented value.
*/ */
uint16_t core_util_atomic_decr_u16(uint16_t * valuePtr, uint16_t delta); uint16_t core_util_atomic_decr_u16(uint16_t *valuePtr, uint16_t delta);
/** /**
* Atomic decrement. * Atomic decrement.
@ -267,7 +333,18 @@ uint16_t core_util_atomic_decr_u16(uint16_t * valuePtr, uint16_t delta);
* @param delta The amount being decremented. * @param delta The amount being decremented.
* @return The new decremented value. * @return The new decremented value.
*/ */
uint32_t core_util_atomic_decr_u32(uint32_t * valuePtr, uint32_t delta); uint32_t core_util_atomic_decr_u32(uint32_t *valuePtr, uint32_t delta);
/**
* Atomic decrement.
* @param valuePtr Target memory location being decremented.
* @param delta The amount being decremented in bytes.
* @return The new decremented value.
*
* @note The type of the pointer argument is not taken into account
* and the pointer is decremented by bytes
*/
void *core_util_atomic_decr_ptr(void **valuePtr, ptrdiff_t delta);
#ifdef __cplusplus #ifdef __cplusplus
} // extern "C" } // extern "C"

51
hal/common/critical.c
View File

@ -15,15 +15,11 @@
* limitations under the License. * limitations under the License.
*/ */
#define __STDC_LIMIT_MACROS #include "critical.h"
#include <stdint.h>
#include <stddef.h>
#include "cmsis.h" #include "cmsis.h"
#include "mbed_assert.h" #include "mbed_assert.h"
// Module include
#include "critical.h"
#define EXCLUSIVE_ACCESS (!defined (__CORTEX_M0) && !defined (__CORTEX_M0PLUS)) #define EXCLUSIVE_ACCESS (!defined (__CORTEX_M0) && !defined (__CORTEX_M0PLUS))
static volatile uint32_t interrupt_enable_counter = 0; static volatile uint32_t interrupt_enable_counter = 0;
@ -38,7 +34,7 @@ bool core_util_are_interrupts_enabled(void)
#endif #endif
} }
void core_util_critical_section_enter() void core_util_critical_section_enter(void)
{ {
bool interrupts_disabled = !core_util_are_interrupts_enabled(); bool interrupts_disabled = !core_util_are_interrupts_enabled();
__disable_irq(); __disable_irq();
@ -63,7 +59,7 @@ void core_util_critical_section_enter()
interrupt_enable_counter++; interrupt_enable_counter++;
} }
void core_util_critical_section_exit() void core_util_critical_section_exit(void)
{ {
/* If critical_section_enter has not previously been called, do nothing */ /* If critical_section_enter has not previously been called, do nothing */
if (interrupt_enable_counter) { if (interrupt_enable_counter) {
@ -127,7 +123,7 @@ bool core_util_atomic_cas_u32(uint32_t *ptr, uint32_t *expectedCurrentValue, uin
return !__STREXW(desiredValue, (volatile uint32_t*)ptr); return !__STREXW(desiredValue, (volatile uint32_t*)ptr);
} }
uint8_t core_util_atomic_incr_u8(uint8_t * valuePtr, uint8_t delta) uint8_t core_util_atomic_incr_u8(uint8_t *valuePtr, uint8_t delta)
{ {
uint8_t newValue; uint8_t newValue;
do { do {
@ -136,7 +132,7 @@ uint8_t core_util_atomic_incr_u8(uint8_t * valuePtr, uint8_t delta)
return newValue; return newValue;
} }
uint16_t core_util_atomic_incr_u16(uint16_t * valuePtr, uint16_t delta) uint16_t core_util_atomic_incr_u16(uint16_t *valuePtr, uint16_t delta)
{ {
uint16_t newValue; uint16_t newValue;
do { do {
@ -145,7 +141,7 @@ uint16_t core_util_atomic_incr_u16(uint16_t * valuePtr, uint16_t delta)
return newValue; return newValue;
} }
uint32_t core_util_atomic_incr_u32(uint32_t * valuePtr, uint32_t delta) uint32_t core_util_atomic_incr_u32(uint32_t *valuePtr, uint32_t delta)
{ {
uint32_t newValue; uint32_t newValue;
do { do {
@ -155,7 +151,7 @@ uint32_t core_util_atomic_incr_u32(uint32_t * valuePtr, uint32_t delta)
} }
uint8_t core_util_atomic_decr_u8(uint8_t * valuePtr, uint8_t delta) uint8_t core_util_atomic_decr_u8(uint8_t *valuePtr, uint8_t delta)
{ {
uint8_t newValue; uint8_t newValue;
do { do {
@ -164,7 +160,7 @@ uint8_t core_util_atomic_decr_u8(uint8_t * valuePtr, uint8_t delta)
return newValue; return newValue;
} }
uint16_t core_util_atomic_decr_u16(uint16_t * valuePtr, uint16_t delta) uint16_t core_util_atomic_decr_u16(uint16_t *valuePtr, uint16_t delta)
{ {
uint16_t newValue; uint16_t newValue;
do { do {
@ -173,7 +169,7 @@ uint16_t core_util_atomic_decr_u16(uint16_t * valuePtr, uint16_t delta)
return newValue; return newValue;
} }
uint32_t core_util_atomic_decr_u32(uint32_t * valuePtr, uint32_t delta) uint32_t core_util_atomic_decr_u32(uint32_t *valuePtr, uint32_t delta)
{ {
uint32_t newValue; uint32_t newValue;
do { do {
@ -236,7 +232,14 @@ bool core_util_atomic_cas_u32(uint32_t *ptr, uint32_t *expectedCurrentValue, uin
return success; return success;
} }
uint8_t core_util_atomic_incr_u8(uint8_t * valuePtr, uint8_t delta) bool core_util_atomic_cas_ptr(void **ptr, void **expectedCurrentValue, void *desiredValue) {
return core_util_atomic_cas_u32(
(uintptr_t *)ptr,
(uintptr_t *)expectedCurrentValue,
(uintptr_t)desiredValue);
}
uint8_t core_util_atomic_incr_u8(uint8_t *valuePtr, uint8_t delta)
{ {
uint8_t newValue; uint8_t newValue;
core_util_critical_section_enter(); core_util_critical_section_enter();
@ -246,7 +249,7 @@ uint8_t core_util_atomic_incr_u8(uint8_t * valuePtr, uint8_t delta)
return newValue; return newValue;
} }
uint16_t core_util_atomic_incr_u16(uint16_t * valuePtr, uint16_t delta) uint16_t core_util_atomic_incr_u16(uint16_t *valuePtr, uint16_t delta)
{ {
uint16_t newValue; uint16_t newValue;
core_util_critical_section_enter(); core_util_critical_section_enter();
@ -256,7 +259,7 @@ uint16_t core_util_atomic_incr_u16(uint16_t * valuePtr, uint16_t delta)
return newValue; return newValue;
} }
uint32_t core_util_atomic_incr_u32(uint32_t * valuePtr, uint32_t delta) uint32_t core_util_atomic_incr_u32(uint32_t *valuePtr, uint32_t delta)
{ {
uint32_t newValue; uint32_t newValue;
core_util_critical_section_enter(); core_util_critical_section_enter();
@ -266,8 +269,12 @@ uint32_t core_util_atomic_incr_u32(uint32_t * valuePtr, uint32_t delta)
return newValue; return newValue;
} }
void *core_util_atomic_incr_ptr(void **valuePtr, ptrdiff_t delta) {
return core_util_atomic_incr((uintptr_t)valuePtr, (uintptr_t)delta);
}
uint8_t core_util_atomic_decr_u8(uint8_t * valuePtr, uint8_t delta)
uint8_t core_util_atomic_decr_u8(uint8_t *valuePtr, uint8_t delta)
{ {
uint8_t newValue; uint8_t newValue;
core_util_critical_section_enter(); core_util_critical_section_enter();
@ -277,7 +284,7 @@ uint8_t core_util_atomic_decr_u8(uint8_t * valuePtr, uint8_t delta)
return newValue; return newValue;
} }
uint16_t core_util_atomic_decr_u16(uint16_t * valuePtr, uint16_t delta) uint16_t core_util_atomic_decr_u16(uint16_t *valuePtr, uint16_t delta)
{ {
uint16_t newValue; uint16_t newValue;
core_util_critical_section_enter(); core_util_critical_section_enter();
@ -287,7 +294,7 @@ uint16_t core_util_atomic_decr_u16(uint16_t * valuePtr, uint16_t delta)
return newValue; return newValue;
} }
uint32_t core_util_atomic_decr_u32(uint32_t * valuePtr, uint32_t delta) uint32_t core_util_atomic_decr_u32(uint32_t *valuePtr, uint32_t delta)
{ {
uint32_t newValue; uint32_t newValue;
core_util_critical_section_enter(); core_util_critical_section_enter();
@ -297,5 +304,9 @@ uint32_t core_util_atomic_decr_u32(uint32_t * valuePtr, uint32_t delta)
return newValue; return newValue;
} }
void *core_util_atomic_decr_ptr(void **valuePtr, ptrdiff_t delta) {
return core_util_atomic_decr((uintptr_t)valuePtr, (uintptr_t)delta);
}
#endif #endif