1 files changed, 14 insertions, 3 deletions

diff --git a/code/fe310/eos/msgq.c b/code/fe310/eos/msgq.c
index 2c31662..867bf94 100644
--- a/code/fe310/eos/msgq.c
+++ b/code/fe310/eos/msgq.c
@@ -3,7 +3,12 @@
 #include "eos.h"
 #include "msgq.h"
 
-#define EOS_MSGQ_IDX_MASK(IDX, SIZE)  ((IDX) & ((SIZE) - 1))
+#define EOS_MSGQ_IDX_MASK(IDX, SIZE)    ((IDX) & ((SIZE) - 1))
+
+#define EOS_MSGQ_IDX_HALF               ((uint8_t)1 << (sizeof(uint8_t) * 8 - 1))
+#define EOS_MSGQ_IDX_LT(a,b)            ((uint8_t)((uint8_t)(a) - (uint8_t)(b)) > EOS_MSGQ_IDX_HALF)
+#define EOS_MSGQ_IDX_LTE(a,b)           ((uint8_t)((uint8_t)(b) - (uint8_t)(a)) < EOS_MSGQ_IDX_HALF)
+
 
 void eos_msgq_init(EOSMsgQ *msgq, EOSMsgItem *array, uint8_t size) {
     msgq->idx_r = 0;
@@ -13,7 +18,7 @@ void eos_msgq_init(EOSMsgQ *msgq, EOSMsgItem *array, uint8_t size) {
 }
 
 int eos_msgq_push(EOSMsgQ *msgq, unsigned char type, unsigned char *buffer, uint16_t len) {
-    if (msgq->idx_w - msgq->idx_r == msgq->size) return EOS_ERR_Q_FULL;
+    if ((uint8_t)(msgq->idx_w - msgq->idx_r) == msgq->size) return EOS_ERR_Q_FULL;
 
     uint8_t idx = EOS_MSGQ_IDX_MASK(msgq->idx_w, msgq->size);
     msgq->array[idx].type = type;
@@ -37,6 +42,12 @@ void eos_msgq_pop(EOSMsgQ *msgq, unsigned char *type, unsigned char **buffer, ui
 }
 
 void eos_msgq_get(EOSMsgQ *msgq, unsigned char type, unsigned char **buffer, uint16_t *len) {
+    if (msgq->idx_r == msgq->idx_w) {
+        *buffer = NULL;
+        *len = 0;
+        return;
+    }
+    
     uint8_t idx = EOS_MSGQ_IDX_MASK(msgq->idx_r, msgq->size);
     unsigned char _type = msgq->array[idx].type;
     EOSMsgItem *tmp_item = &msgq->array[idx];
@@ -47,7 +58,7 @@ void eos_msgq_get(EOSMsgQ *msgq, unsigned char type, unsigned char **buffer, uin
         msgq->idx_r++;
         return;
     }
-    for (idx = msgq->idx_r + 1; idx < msgq->idx_w; idx++) {
+    for (idx = msgq->idx_r + 1; EOS_MSGQ_IDX_LT(idx, msgq->idx_w); idx++) {
         *tmp_item = msgq->array[EOS_MSGQ_IDX_MASK(idx, msgq->size)];
         msgq->array[EOS_MSGQ_IDX_MASK(idx, msgq->size)].type = _type;
         msgq->array[EOS_MSGQ_IDX_MASK(idx, msgq->size)].buffer = *buffer;