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LPC1768: fix serial buffer underrun (#7854)

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When the buffer is empty index_write == index_read, but they needed constrained by buffer_mask
This commit is contained in:
Chris Pepper 2017-10-05 23:19:43 +01:00 committed by Roxy-3D
parent 46b2773e13
commit aa51a02b8f
1 changed files with 7 additions and 10 deletions
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17
Marlin/src/HAL/HAL_LPC1768/serial.h
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@ -56,12 +56,10 @@ public:
return buffer_size - available();
}
T read() volatile {
if(index_write != index_read) {
T val = buffer[buffer_mask & index_read];
++index_read;
return val;
}
return T(0);
if((buffer_mask & index_read) == (buffer_mask & index_write)) return T(-1);
T val = buffer[buffer_mask & index_read];
++index_read;
return val;
}
bool write( T value) volatile {
uint32_t next_head = buffer_mask & (index_write + 1);
@ -73,10 +71,10 @@ public:
return false;
}
bool empty() volatile {
return index_read == index_write;
return (buffer_mask & index_read) == (buffer_mask & index_write);
}
bool full() volatile {
return index_read == index_write + 1;
return index_read == buffer_mask & (index_write + 1);
}
void clear() volatile {
index_read = index_write = 0;
@ -100,7 +98,6 @@ public:
}
char read() {
if(receive_buffer.empty()) return -1;
return (char)receive_buffer.read();
}
@ -110,7 +107,7 @@ public:
}
operator bool() {
return true;
return host_connected;
}
uint16_t available() {