[PATCH v2 29/29] Replace padlength tables with inline functions from misc.h

[Alan Coopersmith]

Adds new function padding_for_int32() and uses existing pad_to_int32()
depending on required results.

Signed-off-by: Alan Coopersmith <alan.coopersmith at oracle.com>
Reviewed-by: Keith Packard <keithp at keithp.com>
---
 dix/dispatch.c   |    4 +---
 include/misc.h   |   14 ++++++++++++++
 os/io.c          |    6 ++----
 randr/rrscreen.c |    5 +----
 test/input.c     |   34 ++++++++++++++++++++++++++++++++--
 5 files changed, 50 insertions(+), 13 deletions(-)

diff --git a/dix/dispatch.c b/dix/dispatch.c
index a3cf63e..279d6d2 100644
--- a/dix/dispatch.c
+++ b/dix/dispatch.c
@@ -466,8 +466,6 @@ Dispatch(void)
 static int VendorRelease = VENDOR_RELEASE;
 static char *VendorString = VENDOR_NAME;
 
-static const int padlength[4] = { 0, 3, 2, 1 };
-
 void
 SetVendorRelease(int release)
 {
@@ -528,7 +526,7 @@ CreateConnectionBlock(void)
     memmove(pBuf, VendorString, (int) setup.nbytesVendor);
     sizesofar += setup.nbytesVendor;
     pBuf += setup.nbytesVendor;
-    i = padlength[setup.nbytesVendor & 3];
+    i = padding_for_int32(setup.nbytesVendor);
     sizesofar += i;
     while (--i >= 0)
         *pBuf++ = 0;
diff --git a/include/misc.h b/include/misc.h
index aa62f6a..916f08e 100644
--- a/include/misc.h
+++ b/include/misc.h
@@ -228,6 +228,20 @@ pad_to_int32(const int bytes)
     return (((bytes) + 3) & ~3);
 }
 
+/**
+ * Calculate padding needed to bring the number of bytes to an even
+ * multiple of 4.
+ * @param bytes The minimum number of bytes needed.
+ * @return The bytes of padding needed to arrive at the closest multiple of 4
+ * that is equal or higher than bytes.
+ */
+static inline int
+padding_for_int32(const int bytes)
+{
+    return ((-bytes) & 3);
+}
+
+
 extern char **xstrtokenize(const char *str, const char *separators);
 extern void FormatUInt64(uint64_t num, char *string);
 extern void FormatUInt64Hex(uint64_t num, char *string);
diff --git a/os/io.c b/os/io.c
index 8d0e5cc..e44db39 100644
--- a/os/io.c
+++ b/os/io.c
@@ -578,8 +578,6 @@ ResetCurrentRequest(ClientPtr client)
     }
 }
 
-static const int padlength[4] = { 0, 3, 2, 1 };
-
  /********************
  * FlushAllOutput()
  *    Flush all clients with output.  However, if some client still
@@ -757,7 +755,7 @@ WriteToClient(ClientPtr who, int count, const void *__buf)
         oc->output = oco;
     }
 
-    padBytes = padlength[count & 3];
+    padBytes = padding_for_int32(count);
 
     if (ReplyCallback) {
         ReplyInfoRec replyinfo;
@@ -850,7 +848,7 @@ FlushClient(ClientPtr who, OsCommPtr oc, const void *__extraBuf, int extraCount)
     if (!oco)
         return 0;
     written = 0;
-    padsize = padlength[extraCount & 3];
+    padsize = padding_for_int32(extraCount);
     notWritten = oco->count + extraCount + padsize;
     todo = notWritten;
     while (notWritten) {
diff --git a/randr/rrscreen.c b/randr/rrscreen.c
index 94505b4..6a7f032 100644
--- a/randr/rrscreen.c
+++ b/randr/rrscreen.c
@@ -22,8 +22,6 @@
 
 #include "randrstr.h"
 
-static const int padlength[4] = { 0, 3, 2, 1 };
-
 static CARD16
  RR10CurrentSizeID(ScreenPtr pScreen);
 
@@ -46,8 +44,7 @@ RREditConnectionInfo(ScreenPtr pScreen)
     connSetup = (xConnSetup *) ConnectionInfo;
     vendor = (char *) connSetup + sizeof(xConnSetup);
     formats = (xPixmapFormat *) ((char *) vendor +
-                                 connSetup->nbytesVendor +
-                                 padlength[connSetup->nbytesVendor & 3]);
+                                 pad_to_int32(connSetup->nbytesVendor));
     root = (xWindowRoot *) ((char *) formats +
                             sizeof(xPixmapFormat) *
                             screenInfo.numPixmapFormats);
diff --git a/test/input.c b/test/input.c
index 90ab9ae..191c817 100644
--- a/test/input.c
+++ b/test/input.c
@@ -965,6 +965,19 @@ test_pad_to_int32(int i)
 }
 
 static void
+test_padding_for_int32(int i)
+{
+    static const int padlength[4] = { 0, 3, 2, 1 };
+    int expected_bytes = (((i + 3) / 4) * 4) - i;
+
+    assert(padding_for_int32(i) >= 0);
+    assert(padding_for_int32(i) <= 3);
+    assert(padding_for_int32(i) == expected_bytes);
+    assert(padding_for_int32(i) == padlength[i & 3]);
+    assert((padding_for_int32(i) + i) == pad_to_int32(i));
+}
+
+static void
 include_byte_padding_macros(void)
 {
     printf("Testing bits_to_bytes()\n");
@@ -996,12 +1009,12 @@ include_byte_padding_macros(void)
     test_bytes_to_int32(INT_MAX - 4);
     test_bytes_to_int32(INT_MAX - 3);
 
-    printf("Testing pad_to_int32\n");
+    printf("Testing pad_to_int32()\n");
 
     test_pad_to_int32(0);
-    test_pad_to_int32(0);
     test_pad_to_int32(1);
     test_pad_to_int32(2);
+    test_pad_to_int32(3);
     test_pad_to_int32(7);
     test_pad_to_int32(8);
     test_pad_to_int32(0xFF);
@@ -1012,6 +1025,23 @@ include_byte_padding_macros(void)
     test_pad_to_int32(0x1000000);
     test_pad_to_int32(INT_MAX - 4);
     test_pad_to_int32(INT_MAX - 3);
+
+    printf("Testing padding_for_int32()\n");
+
+    test_padding_for_int32(0);
+    test_padding_for_int32(1);
+    test_padding_for_int32(2);
+    test_padding_for_int32(3);
+    test_padding_for_int32(7);
+    test_padding_for_int32(8);
+    test_padding_for_int32(0xFF);
+    test_padding_for_int32(0x100);
+    test_padding_for_int32(0xFFFF);
+    test_padding_for_int32(0x10000);
+    test_padding_for_int32(0xFFFFFF);
+    test_padding_for_int32(0x1000000);
+    test_padding_for_int32(INT_MAX - 4);
+    test_padding_for_int32(INT_MAX - 3);
 }
 
 static void
-- 
1.7.9.2