get rid of undefined behavior regarding order of evaluation

buffer/prs_u16.c

@@ -1,7 +1,8 @@
 #include "parse.h"
 
 uint16_t prs_u16(struct bytestream* bs) {
-  return bs_get(bs) | (bs_get(bs) << 8);
+  unsigned char c = bs_get(bs);
+  return c | (bs_get(bs) << 8);
 }
 
 #ifdef UNITTEST

buffer/prs_u16_big.c

@@ -1,7 +1,8 @@
 #include "parse.h"
 
 uint16_t prs_u16_big(struct bytestream* bs) {
-  return (bs_get(bs) << 8) | bs_get(bs);
+  uint16_t x = bs_get(bs) << 8;
+  return x | bs_get(bs);
 }
 
 #ifdef UNITTEST

buffer/prs_u32.c

@@ -1,7 +1,10 @@
 #include "parse.h"
 
 uint32_t prs_u32(struct bytestream* bs) {
-  return bs_get(bs) | (bs_get(bs) << 8) | (bs_get(bs) << 16) | (bs_get(bs) << 24);
+  uint32_t x = bs_get(bs);
+  x |= bs_get(bs) << 8;
+  x |= bs_get(bs) << 16;
+  return x | (bs_get(bs) << 24);
 }
 
 #ifdef UNITTEST

buffer/prs_u32_big.c

@@ -1,7 +1,10 @@
 #include "parse.h"
 
 uint32_t prs_u32_big(struct bytestream* bs) {
-  return (bs_get(bs) << 24) | (bs_get(bs) << 16) | (bs_get(bs) << 8) | bs_get(bs);
+  uint32_t x = bs_get(bs) << 24;
+  x |= bs_get(bs) << 16;
+  x |= bs_get(bs) << 8;
+  return x | bs_get(bs);
 }
 
 #ifdef UNITTEST