LPC1768: fix serial buffer underrun (#7854)
When the buffer is empty index_write == index_read, but they needed constrained by buffer_mask
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1 changed files with 7 additions and 10 deletions
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@ -56,12 +56,10 @@ public:
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return buffer_size - available();
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}
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T read() volatile {
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if(index_write != index_read) {
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T val = buffer[buffer_mask & index_read];
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++index_read;
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return val;
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}
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return T(0);
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if((buffer_mask & index_read) == (buffer_mask & index_write)) return T(-1);
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T val = buffer[buffer_mask & index_read];
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++index_read;
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return val;
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}
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bool write( T value) volatile {
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uint32_t next_head = buffer_mask & (index_write + 1);
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@ -73,10 +71,10 @@ public:
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return false;
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}
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bool empty() volatile {
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return index_read == index_write;
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return (buffer_mask & index_read) == (buffer_mask & index_write);
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}
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bool full() volatile {
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return index_read == index_write + 1;
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return index_read == buffer_mask & (index_write + 1);
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}
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void clear() volatile {
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index_read = index_write = 0;
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@ -100,7 +98,6 @@ public:
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}
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char read() {
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if(receive_buffer.empty()) return -1;
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return (char)receive_buffer.read();
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}
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@ -110,7 +107,7 @@ public:
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}
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operator bool() {
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return true;
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return host_connected;
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}
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uint16_t available() {
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