Fixes to exception support for Duet 3

6 files changed, 473 insertions, 0 deletions

diff --git a/src/libc/local.h b/src/libc/local.h
new file mode 100644
index 00000000..c4bf6af8
--- /dev/null
+++ b/src/libc/local.h
@@ -0,0 +1,23 @@
+#include <_ansi.h>
+
+#if 0	// dc42
+#include <../ctype/local.h>
+
+/* internal function to compute width of wide char. */
+int __wcwidth (wint_t);
+#endif
+
+/*
+   Taken from glibc:
+   Add the compiler optimization to inhibit loop transformation to library
+   calls.  This is used to avoid recursive calls in memset and memmove
+   default implementations.
+*/
+#ifdef _HAVE_CC_INHIBIT_LOOP_TO_LIBCALL
+# define __inhibit_loop_to_libcall \
+  __attribute__ ((__optimize__ ("-fno-tree-loop-distribute-patterns")))
+#else
+# define __inhibit_loop_to_libcall
+#endif
+
+
diff --git a/src/libc/memcmp.c b/src/libc/memcmp.c
new file mode 100644
index 00000000..342fb9fb
--- /dev/null
+++ b/src/libc/memcmp.c
@@ -0,0 +1,105 @@
+/*
+FUNCTION
+	<<memcmp>>---compare two memory areas
+
+INDEX
+	memcmp
+
+SYNOPSIS
+	#include <string.h>
+	int memcmp(const void *<[s1]>, const void *<[s2]>, size_t <[n]>);
+
+DESCRIPTION
+	This function compares not more than <[n]> characters of the
+	object pointed to by <[s1]> with the object pointed to by <[s2]>.
+
+
+RETURNS
+	The function returns an integer greater than, equal to or
+	less than zero 	according to whether the object pointed to by
+	<[s1]> is greater than, equal to or less than the object
+	pointed to by <[s2]>.
+
+PORTABILITY
+<<memcmp>> is ANSI C.
+
+<<memcmp>> requires no supporting OS subroutines.
+
+QUICKREF
+	memcmp ansi pure
+*/
+
+#include <string.h>
+
+
+/* Nonzero if either X or Y is not aligned on a "long" boundary.  */
+#define UNALIGNED(X, Y) \
+  (((long)X & (sizeof (long) - 1)) | ((long)Y & (sizeof (long) - 1)))
+
+/* How many bytes are copied each iteration of the word copy loop.  */
+#define LBLOCKSIZE (sizeof (long))
+
+/* Threshhold for punting to the byte copier.  */
+#define TOO_SMALL(LEN)  ((LEN) < LBLOCKSIZE)
+
+int
+memcmp (const void *m1,
+	const void *m2,
+	size_t n)
+{
+#if defined(PREFER_SIZE_OVER_SPEED) || defined(__OPTIMIZE_SIZE__)
+  unsigned char *s1 = (unsigned char *) m1;
+  unsigned char *s2 = (unsigned char *) m2;
+
+  while (n--)
+    {
+      if (*s1 != *s2)
+	{
+	  return *s1 - *s2;
+	}
+      s1++;
+      s2++;
+    }
+  return 0;
+#else  
+  unsigned char *s1 = (unsigned char *) m1;
+  unsigned char *s2 = (unsigned char *) m2;
+  unsigned long *a1;
+  unsigned long *a2;
+
+  /* If the size is too small, or either pointer is unaligned,
+     then we punt to the byte compare loop.  Hopefully this will
+     not turn up in inner loops.  */
+  if (!TOO_SMALL(n) && !UNALIGNED(s1,s2))
+    {
+      /* Otherwise, load and compare the blocks of memory one 
+         word at a time.  */
+      a1 = (unsigned long*) s1;
+      a2 = (unsigned long*) s2;
+      while (n >= LBLOCKSIZE)
+        {
+          if (*a1 != *a2) 
+   	    break;
+          a1++;
+          a2++;
+          n -= LBLOCKSIZE;
+        }
+
+      /* check m mod LBLOCKSIZE remaining characters */
+
+      s1 = (unsigned char*)a1;
+      s2 = (unsigned char*)a2;
+    }
+
+  while (n--)
+    {
+      if (*s1 != *s2)
+	return *s1 - *s2;
+      s1++;
+      s2++;
+    }
+
+  return 0;
+#endif /* not PREFER_SIZE_OVER_SPEED */
+}
+
diff --git a/src/libc/memcpy.c b/src/libc/memcpy.c
new file mode 100644
index 00000000..52f716b9
--- /dev/null
+++ b/src/libc/memcpy.c
@@ -0,0 +1,105 @@
+/*
+FUNCTION
+        <<memcpy>>---copy memory regions
+
+SYNOPSIS
+        #include <string.h>
+        void* memcpy(void *restrict <[out]>, const void *restrict <[in]>,
+                     size_t <[n]>);
+
+DESCRIPTION
+        This function copies <[n]> bytes from the memory region
+        pointed to by <[in]> to the memory region pointed to by
+        <[out]>.
+
+        If the regions overlap, the behavior is undefined.
+
+RETURNS
+        <<memcpy>> returns a pointer to the first byte of the <[out]>
+        region.
+
+PORTABILITY
+<<memcpy>> is ANSI C.
+
+<<memcpy>> requires no supporting OS subroutines.
+
+QUICKREF
+        memcpy ansi pure
+	*/
+
+#include <_ansi.h>
+#include <string.h>
+#include "local.h"
+
+/* Nonzero if either X or Y is not aligned on a "long" boundary.  */
+#define UNALIGNED(X, Y) \
+  (((long)X & (sizeof (long) - 1)) | ((long)Y & (sizeof (long) - 1)))
+
+/* How many bytes are copied each iteration of the 4X unrolled loop.  */
+#define BIGBLOCKSIZE    (sizeof (long) << 2)
+
+/* How many bytes are copied each iteration of the word copy loop.  */
+#define LITTLEBLOCKSIZE (sizeof (long))
+
+/* Threshhold for punting to the byte copier.  */
+#define TOO_SMALL(LEN)  ((LEN) < BIGBLOCKSIZE)
+
+void *
+__inhibit_loop_to_libcall
+memcpy (void *__restrict dst0,
+	const void *__restrict src0,
+	size_t len0)
+{
+#if defined(PREFER_SIZE_OVER_SPEED) || defined(__OPTIMIZE_SIZE__)
+  char *dst = (char *) dst0;
+  char *src = (char *) src0;
+
+  void *save = dst0;
+
+  while (len0--)
+    {
+      *dst++ = *src++;
+    }
+
+  return save;
+#else
+  char *dst = dst0;
+  const char *src = src0;
+  long *aligned_dst;
+  const long *aligned_src;
+
+  /* If the size is small, or either SRC or DST is unaligned,
+     then punt into the byte copy loop.  This should be rare.  */
+  if (!TOO_SMALL(len0) && !UNALIGNED (src, dst))
+    {
+      aligned_dst = (long*)dst;
+      aligned_src = (long*)src;
+
+      /* Copy 4X long words at a time if possible.  */
+      while (len0 >= BIGBLOCKSIZE)
+        {
+          *aligned_dst++ = *aligned_src++;
+          *aligned_dst++ = *aligned_src++;
+          *aligned_dst++ = *aligned_src++;
+          *aligned_dst++ = *aligned_src++;
+          len0 -= BIGBLOCKSIZE;
+        }
+
+      /* Copy one long word at a time if possible.  */
+      while (len0 >= LITTLEBLOCKSIZE)
+        {
+          *aligned_dst++ = *aligned_src++;
+          len0 -= LITTLEBLOCKSIZE;
+        }
+
+       /* Pick up any residual with a byte copier.  */
+      dst = (char*)aligned_dst;
+      src = (char*)aligned_src;
+    }
+
+  while (len0--)
+    *dst++ = *src++;
+
+  return dst0;
+#endif /* not PREFER_SIZE_OVER_SPEED */
+}
diff --git a/src/libc/memmove.c b/src/libc/memmove.c
new file mode 100644
index 00000000..da5dfdbd
--- /dev/null
+++ b/src/libc/memmove.c
@@ -0,0 +1,136 @@
+/*
+FUNCTION
+	<<memmove>>---move possibly overlapping memory
+
+INDEX
+	memmove
+
+SYNOPSIS
+	#include <string.h>
+	void *memmove(void *<[dst]>, const void *<[src]>, size_t <[length]>);
+
+DESCRIPTION
+	This function moves <[length]> characters from the block of
+	memory starting at <<*<[src]>>> to the memory starting at
+	<<*<[dst]>>>. <<memmove>> reproduces the characters correctly
+	at <<*<[dst]>>> even if the two areas overlap.
+
+
+RETURNS
+	The function returns <[dst]> as passed.
+
+PORTABILITY
+<<memmove>> is ANSI C.
+
+<<memmove>> requires no supporting OS subroutines.
+
+QUICKREF
+	memmove ansi pure
+*/
+
+#include <string.h>
+#include <_ansi.h>
+#include <stddef.h>
+#include <limits.h>
+#include "local.h"
+
+/* Nonzero if either X or Y is not aligned on a "long" boundary.  */
+#define UNALIGNED(X, Y) \
+  (((long)X & (sizeof (long) - 1)) | ((long)Y & (sizeof (long) - 1)))
+
+/* How many bytes are copied each iteration of the 4X unrolled loop.  */
+#define BIGBLOCKSIZE    (sizeof (long) << 2)
+
+/* How many bytes are copied each iteration of the word copy loop.  */
+#define LITTLEBLOCKSIZE (sizeof (long))
+
+/* Threshhold for punting to the byte copier.  */
+#define TOO_SMALL(LEN)  ((LEN) < BIGBLOCKSIZE)
+
+/*SUPPRESS 20*/
+void *
+__inhibit_loop_to_libcall
+memmove (void *dst_void,
+	const void *src_void,
+	size_t length)
+{
+#if defined(PREFER_SIZE_OVER_SPEED) || defined(__OPTIMIZE_SIZE__)
+  char *dst = dst_void;
+  const char *src = src_void;
+
+  if (src < dst && dst < src + length)
+    {
+      /* Have to copy backwards */
+      src += length;
+      dst += length;
+      while (length--)
+	{
+	  *--dst = *--src;
+	}
+    }
+  else
+    {
+      while (length--)
+	{
+	  *dst++ = *src++;
+	}
+    }
+
+  return dst_void;
+#else
+  char *dst = dst_void;
+  const char *src = src_void;
+  long *aligned_dst;
+  const long *aligned_src;
+
+  if (src < dst && dst < src + length)
+    {
+      /* Destructive overlap...have to copy backwards */
+      src += length;
+      dst += length;
+      while (length--)
+	{
+	  *--dst = *--src;
+	}
+    }
+  else
+    {
+      /* Use optimizing algorithm for a non-destructive copy to closely 
+         match memcpy. If the size is small or either SRC or DST is unaligned,
+         then punt into the byte copy loop.  This should be rare.  */
+      if (!TOO_SMALL(length) && !UNALIGNED (src, dst))
+        {
+          aligned_dst = (long*)dst;
+          aligned_src = (long*)src;
+
+          /* Copy 4X long words at a time if possible.  */
+          while (length >= BIGBLOCKSIZE)
+            {
+              *aligned_dst++ = *aligned_src++;
+              *aligned_dst++ = *aligned_src++;
+              *aligned_dst++ = *aligned_src++;
+              *aligned_dst++ = *aligned_src++;
+              length -= BIGBLOCKSIZE;
+            }
+
+          /* Copy one long word at a time if possible.  */
+          while (length >= LITTLEBLOCKSIZE)
+            {
+              *aligned_dst++ = *aligned_src++;
+              length -= LITTLEBLOCKSIZE;
+            }
+
+          /* Pick up any residual with a byte copier.  */
+          dst = (char*)aligned_dst;
+          src = (char*)aligned_src;
+        }
+
+      while (length--)
+        {
+          *dst++ = *src++;
+        }
+    }
+
+  return dst_void;
+#endif /* not PREFER_SIZE_OVER_SPEED */
+}
diff --git a/src/libc/memset.c b/src/libc/memset.c
new file mode 100644
index 00000000..e8e667a2
--- /dev/null
+++ b/src/libc/memset.c
@@ -0,0 +1,96 @@
+/*
+FUNCTION
+	<<memset>>---set an area of memory
+
+INDEX
+	memset
+
+SYNOPSIS
+	#include <string.h>
+	void *memset(void *<[dst]>, int <[c]>, size_t <[length]>);
+
+DESCRIPTION
+	This function converts the argument <[c]> into an unsigned
+	char and fills the first <[length]> characters of the array
+	pointed to by <[dst]> to the value.
+
+RETURNS
+	<<memset>> returns the value of <[dst]>.
+
+PORTABILITY
+<<memset>> is ANSI C.
+
+    <<memset>> requires no supporting OS subroutines.
+
+QUICKREF
+	memset ansi pure
+*/
+
+#include <string.h>
+#include "local.h"
+
+#define LBLOCKSIZE (sizeof(long))
+#define UNALIGNED(X)   ((long)X & (LBLOCKSIZE - 1))
+#define TOO_SMALL(LEN) ((LEN) < LBLOCKSIZE)
+
+void *
+__inhibit_loop_to_libcall
+memset (void *m,
+	int c,
+	size_t n)
+{
+  char *s = (char *) m;
+
+#if !defined(PREFER_SIZE_OVER_SPEED) && !defined(__OPTIMIZE_SIZE__)
+  unsigned int i;
+  unsigned long buffer;
+  unsigned long *aligned_addr;
+  unsigned int d = c & 0xff;	/* To avoid sign extension, copy C to an
+				   unsigned variable.  */
+
+  while (UNALIGNED (s))
+    {
+      if (n--)
+        *s++ = (char) c;
+      else
+        return m;
+    }
+
+  if (!TOO_SMALL (n))
+    {
+      /* If we get this far, we know that n is large and s is word-aligned. */
+      aligned_addr = (unsigned long *) s;
+
+      /* Store D into each char sized location in BUFFER so that
+         we can set large blocks quickly.  */
+      buffer = (d << 8) | d;
+      buffer |= (buffer << 16);
+      for (i = 32; i < LBLOCKSIZE * 8; i <<= 1)
+        buffer = (buffer << i) | buffer;
+
+      /* Unroll the loop.  */
+      while (n >= LBLOCKSIZE*4)
+        {
+          *aligned_addr++ = buffer;
+          *aligned_addr++ = buffer;
+          *aligned_addr++ = buffer;
+          *aligned_addr++ = buffer;
+          n -= 4*LBLOCKSIZE;
+        }
+
+      while (n >= LBLOCKSIZE)
+        {
+          *aligned_addr++ = buffer;
+          n -= LBLOCKSIZE;
+        }
+      /* Pick up the remainder with a bytewise loop.  */
+      s = (char*)aligned_addr;
+    }
+
+#endif /* not PREFER_SIZE_OVER_SPEED */
+
+  while (n--)
+    *s++ = (char) c;
+
+  return m;
+}
diff --git a/src/libc/readme-libc.txt b/src/libc/readme-libc.txt
new file mode 100644
index 00000000..40c60f62
--- /dev/null
+++ b/src/libc/readme-libc.txt
@@ -0,0 +1,8 @@
+README file for libc folder
+===========================
+
+On ARM Cortex M7 processors, accesses to strongly-ordered memory such as our "nocache" RAM segment must be aligned. Therefore we compile with option -fno-unaligned-access.
+Unfortunately, newlib (the standard C library) isn't compiled with -fno-unaligned-access, and memcpy in particular sometimes does unaligned accesses.
+To fix this, we include our own copy of memcpy here. Similarly for other memory-related functions that might be used to access DMA buffers.
+
+DC 2019-12-24