Fill out functions in <inttypes.h> except [w]strto*

mos-platform/common/c/CMakeLists.txt

@@ -9,6 +9,9 @@ add_platform_library(common-c
   # errno.h
   errno.c
 
+  # inttypes.h
+  inttypes.c
+
   # setjmp.h
   setjmp.S
 

mos-platform/common/c/inttypes.c

@@ -0,0 +1,10 @@
+#include <inttypes.h>
+
+intmax_t imaxabs(intmax_t j) {
+  return __builtin_llabs(j);
+}
+
+imaxdiv_t imaxdiv(intmax_t numer, intmax_t denom) {
+  imaxdiv_t result = {numer / denom, numer % denom};
+  return result;
+}

mos-platform/common/include/inttypes.h

@@ -169,4 +169,12 @@
 #define SCNxMAX __UINTMAX_FMTx__
 #define SCNxPTR __UINTPTR_FMTx__
 
+intmax_t imaxabs(intmax_t j);
+
+typedef struct {
+  intmax_t quot, rem;
+} imaxdiv_t;
+
+imaxdiv_t imaxdiv(intmax_t numer, intmax_t denom);
+
 #endif // not _INTTYPES_H_