From 8509784d8000d6791a205626e81b03b3f9bf856b Mon Sep 17 00:00:00 2001
From: Anish Athalye <me@anishathalye.com>
Date: Tue, 8 Oct 2019 21:18:54 -0400
Subject: Add implementations of memcmp and memcpy to ulib

This is necessary because gcc may generate calls to memcmp, memset,
memcpy, and memmove when compiling with -nostdlib.
---
 user/ulib.c | 20 ++++++++++++++++++++
 1 file changed, 20 insertions(+)

(limited to 'user/ulib.c')

diff --git a/user/ulib.c b/user/ulib.c
index ddda0f5..8bfba5d 100644
--- a/user/ulib.c
+++ b/user/ulib.c
@@ -107,3 +107,23 @@ memmove(void *vdst, const void *vsrc, int n)
     *dst++ = *src++;
   return vdst;
 }
+
+int
+memcmp(const void *s1, const void *s2, uint n)
+{
+  const char *p1 = s1, *p2 = s2;
+  while (n-- > 0) {
+    if (*p1 != *p2) {
+      return *p1 - *p2;
+    }
+    p1++;
+    p2++;
+  }
+  return 0;
+}
+
+void *
+memcpy(void *dst, const void *src, uint n)
+{
+  return memmove(dst, src, n);
+}
-- 
cgit v1.2.3


From f2df0fa5471c9951ff9a12bea51efbe22afb196e Mon Sep 17 00:00:00 2001
From: Anish Athalye <me@anishathalye.com>
Date: Tue, 8 Oct 2019 21:24:03 -0400
Subject: Fix ulib's memmove to handle overlap when src<dst

---
 user/ulib.c | 11 +++++++++--
 1 file changed, 9 insertions(+), 2 deletions(-)

(limited to 'user/ulib.c')

diff --git a/user/ulib.c b/user/ulib.c
index 8bfba5d..4775939 100644
--- a/user/ulib.c
+++ b/user/ulib.c
@@ -103,8 +103,15 @@ memmove(void *vdst, const void *vsrc, int n)
 
   dst = vdst;
   src = vsrc;
-  while(n-- > 0)
-    *dst++ = *src++;
+  if (src > dst) {
+    while(n-- > 0)
+      *dst++ = *src++;
+  } else {
+    dst += n;
+    src += n;
+    while(n-- > 0)
+      *--dst = *--src;
+  }
   return vdst;
 }
 
-- 
cgit v1.2.3