Refactor libc stubs into libwrap

The --wrap feature of GNU ld supports a cleaner framework for linking in
alternative implementations of libc functions without cpp hacks.
Place wrappers in separate object files to reduce static code size.

4 files changed, 7 insertions, 18 deletions

diff --git a/software/dhrystone/.gitignore b/software/dhrystone/.gitignore
new file mode 100644
index 0000000..eb51a6c
--- /dev/null
+++ b/software/dhrystone/.gitignore
@@ -0,0 +1 @@
+dhrystone
diff --git a/software/dhrystone/Makefile b/software/dhrystone/Makefile
index 2058ca1..a55b1ec 100644
--- a/software/dhrystone/Makefile
+++ b/software/dhrystone/Makefile
@@ -5,10 +5,11 @@ C_SRCS := dhry_stubs.c dhry_printf.c
 HEADERS := dhry.h
 
 DHRY_SRCS := dhry_1.c dhry_2.c
-DHRY_CFLAGS := -O2 -DTIME -fno-inline -Wno-implicit
+DHRY_CFLAGS := -O2 -DTIME -fno-inline -fno-builtin-printf -Wno-implicit
 
 XLEN ?= 32
-CFLAGS := -Dscanf=dhry_scanf -Dprintf=dhry_printf -Os -fno-common
+CFLAGS := -Os -fno-common
+LDFLAGS := -Wl,--wrap=scanf -Wl,--wrap=printf
 
 DHRY_OBJS := $(patsubst %.c,%.o,$(DHRY_SRCS))
 LINK_OBJS := $(DHRY_OBJS)
diff --git a/software/dhrystone/dhry_printf.c b/software/dhrystone/dhry_printf.c
index 1fdaac4..025d231 100644
--- a/software/dhrystone/dhry_printf.c
+++ b/software/dhrystone/dhry_printf.c
@@ -246,7 +246,7 @@ static void vprintfmt(void (*putch)(int, void**), void **putdat, const char *fmt
   }
 }
 
-int printf(const char* fmt, ...)
+int __wrap_printf(const char* fmt, ...)
 {
   va_list ap;
   va_start(ap, fmt);
@@ -257,7 +257,7 @@ int printf(const char* fmt, ...)
   return 0; // incorrect return value, but who cares, anyway?
 }
 
-int sprintf(char* str, const char* fmt, ...)
+int __wrap_sprintf(char* str, const char* fmt, ...)
 {
   va_list ap;
   char* str0 = str;
diff --git a/software/dhrystone/dhry_stubs.c b/software/dhrystone/dhry_stubs.c
index d384bf1..d3bd14c 100644
--- a/software/dhrystone/dhry_stubs.c
+++ b/software/dhrystone/dhry_stubs.c
@@ -12,20 +12,7 @@ long time(void)
 }
 
 // set the number of dhrystone iterations
-void scanf(const char* fmt, int* n)
+void __wrap_scanf(const char* fmt, int* n)
 {
   *n = 1500000;
 }
-
-// simple memory allocator
-void* malloc(unsigned long sz)
-{
-  extern void* sbrk(long);
-  void* res = sbrk(sz);
-  if ((long)res == -1)
-    return 0;
-  return res;
-}
-
-// simple memory deallocator
-void free(void* ptr) {}