【待测试】使用cpsid i / cpsie i（通过 PRIMASK 保存/恢复）保护临界区

library/ringbuffer/ringbuffer.c

@@ -120,35 +120,46 @@ int rd_RingbufferPut(rd_ringbuf_t *rb, const char *ptr, int length)
 {
     if (!rb || !ptr || length <= 0) return RD_INVALUE;
 
-    unsigned short wi = ATOMIC_LOAD(&rb->m_sWriteIndex, unsigned short, ATOMIC_ORDER_RELAXED);
-    unsigned short ri = ATOMIC_LOAD(&rb->m_sReadIndex, unsigned short, ATOMIC_ORDER_RELAXED);
-    unsigned char wb = ATOMIC_LOAD(&rb->m_bWriteMirror, unsigned char, ATOMIC_ORDER_RELAXED);
-    unsigned char rb_m = ATOMIC_LOAD(&rb->m_bReadMirror, unsigned char, ATOMIC_ORDER_RELAXED);
+    unsigned short wi, ri;
+    unsigned char wb, rb_m;
+    int space, tail;
+    unsigned int primask;
+
+    __asm__ volatile ("mrs %0, primask" : "=r"(primask));
+    __asm__ volatile ("cpsid i" ::: "memory");
+
+    wi = ATOMIC_LOAD(&rb->m_sWriteIndex, unsigned short, ATOMIC_ORDER_RELAXED);
+    ri = ATOMIC_LOAD(&rb->m_sReadIndex, unsigned short, ATOMIC_ORDER_RELAXED);
+    wb = ATOMIC_LOAD(&rb->m_bWriteMirror, unsigned char, ATOMIC_ORDER_RELAXED);
+    rb_m = ATOMIC_LOAD(&rb->m_bReadMirror, unsigned char, ATOMIC_ORDER_RELAXED);
 
-    int space;
     if (wb == rb_m) {
         space = rb->m_iBufsize - (int)(unsigned short)(wi - ri);
     } else {
         space = (int)(unsigned short)(ri - wi);
     }
 
-    if (space <= 0) return 0;
+    if (space <= 0) {
+        __asm__ volatile ("msr primask, %0" :: "r"(primask) : "memory");
+        return 0;
+    }
     if (space < length) length = space;
 
-    /* 写入不跨越尾部 */
-    int tail = rb->m_iBufsize - wi;
+    tail = rb->m_iBufsize - wi;
     if (tail > length) {
         RD_MEMCPY(&rb->m_pcBufPtr[wi], ptr, length);
         wi += length;
     } else {
         RD_MEMCPY(&rb->m_pcBufPtr[wi], ptr, tail);
         RD_MEMCPY(&rb->m_pcBufPtr[0], ptr + tail, length - tail);
-        wb ^= 1;                     /* 翻转镜像位 */
+        wb ^= 1;
         wi = length - tail;
     }
 
     ATOMIC_STORE(&rb->m_sWriteIndex, wi, unsigned short, ATOMIC_ORDER_RELEASE);
     ATOMIC_STORE(&rb->m_bWriteMirror, wb, unsigned char, ATOMIC_ORDER_RELEASE);
+
+    __asm__ volatile ("msr primask, %0" :: "r"(primask) : "memory");
     return length;
 }
 
@@ -165,6 +176,10 @@ int rd_RingbufferPutForce(rd_ringbuf_t *rb, const char *ptr, int length)
 {
     if (!rb || !ptr || length <= 0) return RD_INVALUE;
 
+    unsigned int primask;
+    __asm__ volatile ("mrs %0, primask" : "=r"(primask));
+    __asm__ volatile ("cpsid i" ::: "memory");
+
     int space = rd_RingbufferSpaceLen(rb);
     if (length > rb->m_iBufsize) {
         ptr += length - rb->m_iBufsize;
@@ -174,18 +189,18 @@ int rd_RingbufferPutForce(rd_ringbuf_t *rb, const char *ptr, int length)
     unsigned short wi = ATOMIC_LOAD(&rb->m_sWriteIndex, unsigned short, ATOMIC_ORDER_RELAXED);
     unsigned char wb = ATOMIC_LOAD(&rb->m_bWriteMirror, unsigned char, ATOMIC_ORDER_RELAXED);
 
-    if (rb->m_iBufsize - wi > length) {
+    int tail = rb->m_iBufsize - wi;
+    if (tail > length) {
         RD_MEMCPY(&rb->m_pcBufPtr[wi], ptr, length);
         wi += length;
         if (length > space) {
             ATOMIC_STORE(&rb->m_sReadIndex, wi, unsigned short, ATOMIC_ORDER_RELEASE);
         }
     } else {
-        int first = rb->m_iBufsize - wi;
-        RD_MEMCPY(&rb->m_pcBufPtr[wi], ptr, first);
-        RD_MEMCPY(&rb->m_pcBufPtr[0], ptr + first, length - first);
+        RD_MEMCPY(&rb->m_pcBufPtr[wi], ptr, tail);
+        RD_MEMCPY(&rb->m_pcBufPtr[0], ptr + tail, length - tail);
         wb ^= 1;
-        wi = length - first;
+        wi = length - tail;
         if (length > space) {
             unsigned short ri = ATOMIC_LOAD(&rb->m_sReadIndex, unsigned short, ATOMIC_ORDER_RELAXED);
             if (wi <= ri) wb ^= 1;
@@ -195,6 +210,8 @@ int rd_RingbufferPutForce(rd_ringbuf_t *rb, const char *ptr, int length)
 
     ATOMIC_STORE(&rb->m_sWriteIndex, wi, unsigned short, ATOMIC_ORDER_RELEASE);
     ATOMIC_STORE(&rb->m_bWriteMirror, wb, unsigned char, ATOMIC_ORDER_RELEASE);
+
+    __asm__ volatile ("msr primask, %0" :: "r"(primask) : "memory");
     return length;
 }
 
@@ -296,7 +313,15 @@ int rd_RingbufferPeekLinear(rd_ringbuf_t *rb, char *out, int length)
 int rd_RingbufferPutchar(rd_ringbuf_t *rb, const char ch)
 {
     if (!rb) return RD_INVALUE;
-    if (!rd_RingbufferSpaceLen(rb)) return 0;
+
+    unsigned int primask;
+    __asm__ volatile ("mrs %0, primask" : "=r"(primask));
+    __asm__ volatile ("cpsid i" ::: "memory");
+
+    if (rd_RingbufferSpaceLen(rb) == 0) {
+        __asm__ volatile ("msr primask, %0" :: "r"(primask) : "memory");
+        return 0;
+    }
 
     unsigned short wi = ATOMIC_LOAD(&rb->m_sWriteIndex, unsigned short, ATOMIC_ORDER_RELAXED);
     unsigned char wb = ATOMIC_LOAD(&rb->m_bWriteMirror, unsigned char, ATOMIC_ORDER_RELAXED);
@@ -311,6 +336,8 @@ int rd_RingbufferPutchar(rd_ringbuf_t *rb, const char ch)
 
     ATOMIC_STORE(&rb->m_sWriteIndex, wi, unsigned short, ATOMIC_ORDER_RELEASE);
     ATOMIC_STORE(&rb->m_bWriteMirror, wb, unsigned char, ATOMIC_ORDER_RELEASE);
+
+    __asm__ volatile ("msr primask, %0" :: "r"(primask) : "memory");
     return 1;
 }
 
@@ -326,6 +353,10 @@ int rd_RingbufferPutcharForce(rd_ringbuf_t *rb, const char ch)
 {
     if (!rb) return RD_INVALUE;
 
+    unsigned int primask;
+    __asm__ volatile ("mrs %0, primask" : "=r"(primask));
+    __asm__ volatile ("cpsid i" ::: "memory");
+
     enum ERingBufState old_state = rd_RingbufferStatus(rb);
     unsigned short wi = ATOMIC_LOAD(&rb->m_sWriteIndex, unsigned short, ATOMIC_ORDER_RELAXED);
     unsigned char wb = ATOMIC_LOAD(&rb->m_bWriteMirror, unsigned char, ATOMIC_ORDER_RELAXED);
@@ -349,6 +380,8 @@ int rd_RingbufferPutcharForce(rd_ringbuf_t *rb, const char ch)
 
     ATOMIC_STORE(&rb->m_sWriteIndex, wi, unsigned short, ATOMIC_ORDER_RELEASE);
     ATOMIC_STORE(&rb->m_bWriteMirror, wb, unsigned char, ATOMIC_ORDER_RELEASE);
+
+    __asm__ volatile ("msr primask, %0" :: "r"(primask) : "memory");
     return 1;
 }