[hackers] [libzahl] Add zlsh and zrsh || Mattias Andrée

[git]

commit 7335af89f48b7e144022ca0c50858554fd143818
Author:     Mattias Andrée <maand...@kth.se>
AuthorDate: Wed Mar 2 21:37:15 2016 +0100
Commit:     Mattias Andrée <maand...@kth.se>
CommitDate: Wed Mar 2 21:37:15 2016 +0100

    Add zlsh and zrsh
    
    Signed-off-by: Mattias Andrée <maand...@kth.se>

diff --git a/src/zlsh.c b/src/zlsh.c
new file mode 100644
index 0000000..bc1aa0b
--- /dev/null
+++ b/src/zlsh.c
@@ -0,0 +1,51 @@
+/* See LICENSE file for copyright and license details. */
+#include "internals"
+
+#include <stdlib.h>
+#include <string.h>
+
+
+void
+zlsh(z_t a, z_t b, size_t bits)
+{
+       size_t i, chars, cbits;
+       zahl_char_t carry[] = {0, 0};
+
+       if (zzero(b)) {
+               SET_SIGNUM(a, 0);
+               return;
+       }
+       if (!bits) {
+               if (a != b)
+                       zset(a, b);
+               return;
+       }
+
+       chars = FLOOR_BITS_TO_CHARS(bits);
+       bits = BITS_IN_LAST_CHAR(bits)
+       cbits = BITS_PER_CHAR - 1 - bits;
+
+       a->used = b->used + chars;
+       if (a->alloced < a->used) {
+               a->alloced = a->used;
+               a->chars = realloc(a->chars, a->used * sizeof(*(a->chars)));
+       }
+       (a == b ? memmove : memcpy)(a->chars + chars, b->chars, a->used * 
sizeof(*(a->chars)));
+       memset(a->chars, 0, chars * sizeof(*(a->chars)));
+
+       for (i = chars; i < a->used; i++) {
+               carry[~i & 1] = a->chars[i] >> cbits;
+               a->chars[i] <<= bits;
+               a->chars[i] |= carry[i & 1];
+       }
+       if (carry[i & 1]) {
+               if (a->alloced == a->used) {
+                       a->alloced <<= 1;
+                       a->chars = realloc(a->chars, a->alloced * 
sizeof(*(a->chars)));
+               }
+               a->chars[i] = carry[i & 1];
+               a->used++;
+       }
+
+       SET_SIGNUM(a, zsignum(b));
+}
diff --git a/src/zrsh.c b/src/zrsh.c
new file mode 100644
index 0000000..649ebb3
--- /dev/null
+++ b/src/zrsh.c
@@ -0,0 +1,48 @@
+/* See LICENSE file for copyright and license details. */
+#include "internals"
+
+#include <stdlib.h>
+#include <string.h>
+
+
+void
+zrsh(z_t a, z_t b, size_t bits)
+{
+       size_t i, chars, cbits;
+
+       if (!bits) {
+               if (a != b)
+                       zset(a, b);
+               return;
+       }
+
+       chars = FLOOR_BITS_TO_CHARS(bits);
+
+       if (zzero(b) || chars >= b->used || zbits(b) <= bits) {
+               SET_SIGNUM(a, 0);
+               return;
+       }
+
+       bits = BITS_IN_LAST_CHAR(bits)
+       cbits = BITS_PER_CHAR - 1 - bits;
+
+       if (chars && a == b) {
+               a->used -= chars;
+               memmove(a->chars, a->chars + chars, a->used * 
sizeof(*(a->chars)));
+       } else if (a != b) {
+               a->used = b->used - chars;
+               if (a->alloced < a->used) {
+                       a->alloced = a->used;
+                       a->chars = realloc(a->chars, a->used * 
sizeof(*(a->chars)));
+               }
+               memcpy(a->chars, b->chars + chars, a->used * 
sizeof(*(a->chars)));
+       }
+
+       a->chars[0] >>= bits;
+       for (i = 1; i < a->used; i++) {
+               a->chars[i - 1] |= a->chars[i] >> cbits;
+               a->chars[i] >>= bits;
+       }
+
+       SET_SIGNUM(a, zsignum(b));
+}