1 files changed, 134 insertions, 0 deletions
diff --git a/src/case.c b/src/case.c
new file mode 100644
index 0000000..b3aba2f
--- /dev/null
+++ b/src/case.c
@@ -0,0 +1,134 @@
+#include "case.h"
+#include "str.h"
+
+/**
+  * @file case.c
+  * @author djb
+  * @brief string comparison and helper functions; case insensitive
+  */
+
+int case_diffb(char *s,unsigned int len,char *t)
+{
+  unsigned char x;
+  unsigned char y;
+
+  while (len > 0) {
+    --len;
+    x = *s++ - 'A';
+    if (x <= 'Z' - 'A') x += 'a'; else x += 'A';
+    y = *t++ - 'A';
+    if (y <= 'Z' - 'A') y += 'a'; else y += 'A';
+    if (x != y)
+      return ((int)(unsigned int) x) - ((int)(unsigned int) y);
+  }
+  return 0;
+}
+
+int case_diffs(char *s,char *t)
+{
+  unsigned char x;
+  unsigned char y;
+
+  for (;;) {
+    x = *s++ - 'A';
+    if (x <= 'Z' - 'A') x += 'a'; else x += 'A';
+    y = *t++ - 'A';
+    if (y <= 'Z' - 'A') y += 'a'; else y += 'A';
+    if (x != y) break;
+    if (!x) break;
+  }
+  return ((int)(unsigned int) x) - ((int)(unsigned int) y);
+}
+
+int case_diffrs(char *s,char *t)
+{
+  unsigned char x = 0;
+  unsigned char y = 0;
+  unsigned int lens = str_len(s);
+  unsigned int lent = str_len(t);
+
+  while (lens > 0 && lent > 0) {
+    x = s[--lens] - 'A';
+    if (x <= 'Z' - 'A') x += 'a'; else x += 'A';
+    y = t[--lent] - 'A';
+    if (y <= 'Z' - 'A') y += 'a'; else y += 'A';
+    if (x != y) break;
+    if (!x) break;
+    if (!y) break;
+  }
+  return ((int)(unsigned int) x) - ((int)(unsigned int) y);
+}
+
+void case_lowerb(char *s,unsigned int len)
+{
+  unsigned char x;
+  while (len > 0) {
+    --len;
+    x = *s - 'A';
+    if (x <= 'Z' - 'A') *s = x + 'a';
+    ++s;
+  }
+}
+
+void case_lowers(char *s)
+{
+  unsigned char x;
+  while ((x = *s)) {
+    x -= 'A';
+    if (x <= 'Z' - 'A') *s = x + 'a';
+    ++s;
+  }
+}
+
+void case_upperb(char *s,unsigned int len)
+{
+  unsigned char x;
+  while (len > 0) {
+    --len;
+    x = *s - 'a';
+    if (x <= 'z' - 'a') *s = x + 'A';
+    ++s;
+  }
+}
+
+void case_uppers(char *s)
+{
+  unsigned char x;
+  while ((x = *s)) {
+    x -= 'a';
+    if (x <= 'z' - 'a') *s = x + 'A';
+    ++s;
+  }
+}
+
+int case_startb(char *s,unsigned int len,char *t)
+{
+  unsigned char x;
+  unsigned char y;
+
+  for (;;) {
+    y = *t++ - 'A';
+    if (y <= 'Z' - 'A') y += 'a'; else y += 'A';
+    if (!y) return 1;
+    if (!len) return 0;
+    --len;
+    x = *s++ - 'A';
+    if (x <= 'Z' - 'A') x += 'a'; else x += 'A';
+    if (x != y) return 0;
+  }
+}
+
+int case_starts(char *s,char *t)
+{
+  unsigned char x;
+  unsigned char y;
+
+  for (;;) {
+    x = *s++ - 'A';
+    if (x <= 'Z' - 'A') x += 'a'; else x += 'A';
+    y = *t++ - 'A';
+    if (y <= 'Z' - 'A') y += 'a'; else y += 'A';
+    if (!y) return 1;
+    if (x != y) return 0;
+  }
+}