Changeset 556:2d1a26628a09

Timestamp:

06/01/08 07:22:00 (7 months ago)

Author:

David Anderson <dave@…>

Branch:

default

Message:

Replace strcmp() and strncmp() with streq() and streqn().

We never used the total ordering of strcmp(), we always test for
equality. We might as well use functions specialized in that, with
less that can go wrong.

Location:

nxos

Files:

• base/_fs.c (modified) (1 diff)
• base/drivers/radar.c (modified) (1 diff)
• base/lib/rcmd/_rcmd.c (modified) (2 diffs)
• base/util.c (modified) (1 diff)
• base/util.h (modified) (1 diff)
• systems/tests/main.c (modified) (1 diff)
• systems/tests/tests.c (modified) (12 diffs)
• systems/tests/tests.h (modified) (1 diff)

nxos/base/_fs.c

@@ -54 +54 @@
              FS_FILENAME_LENGTH);
 
-      if (strcmp(nameconv.chars, name) == 0) {
+      if (streq(nameconv.chars, name)) {
         *origin = i;
         return FS_ERR_NO_ERROR;

nxos/base/drivers/radar.c

@@ -95 +95 @@
 
   return nx_radar_read(sensor, RADAR_SENSOR_TYPE, type)
-    && strncmp((char *)type, RADAR_LEGO_SENSOR_TYPE,
-               strlen(RADAR_LEGO_SENSOR_TYPE)) == 0;
+    && streq((char *)type, RADAR_LEGO_SENSOR_TYPE);
 }
 

nxos/base/lib/rcmd/_rcmd.c

@@ -40 +40 @@
 
   while (rcmd_commands[i].name) {
-    if (strncmp(line, rcmd_commands[i].name,
-                strlen(rcmd_commands[i].name)) == 0) {
+    if (streq(line, rcmd_commands[i].name)) {
       *command = rcmd_commands[i];
       return RCMD_ERR_NO_ERROR;
@@ -165 +164 @@
   }
 
-  if (ntokens == 4 && strncmp(line + indices[3], "sync", 4) == 0) {
+  if (ntokens == 4 && streq(line + indices[3], "sync") == 0) {
     nx_sound_freq(freq, duration);
   } else {

nxos/base/util.c

@@ -44 +44 @@
 }
 
-U32 strncmp(const char *a, const char *b, U32 n) {
-  U32 i;
-
+bool streqn(const char *a, const char *b, U32 n) {
   NX_ASSERT(a != NULL && b != NULL);
 
-  for (i=0 ; i<n ; i++) {
-    if (a[i] < b[i]) {
-      return -1;
-    } else if (a[i] > b[i]) {
-      return 1;
-    }
+  while (n--) {
+    if (*a != *b++)
+      return FALSE;
+    if (*a++ == '\0')
+      break;
   }
 
-  return 0;
+  return TRUE;
 }
 
-U32 strcmp(const char *a, const char *b) {
-  return strncmp(a, b, MIN(strlen(a), strlen(b)+1));
+bool streq(const char *a, const char *b) {
+  NX_ASSERT(a != NULL && b != NULL);
+
+  while (*a != '\0' && *b != '\0') {
+    if (*a++ != *b++)
+      return FALSE;
+  }
+
+  return *a == *b ? TRUE : FALSE;
 }
 

nxos/base/util.h

@@ -58 +58 @@
 U32 strlen(const char *str);
 
-/** Order two strings based on a limited amount of input.
+/** Compare two string prefixes for equality.
  *
  * @param a First string to compare.
  * @param b Second string to compare.
  * @param n Number of bytes to compare.
- * @return -1 if @a a sorts before @a b, 1 if @a b sorts before @a a, 0
- *         if both are equivalent up to @a n bytes.
+ * @return TRUE if the first @a n bytes of @a a are equal to @a b,
+ * FALSE otherwise.
+ *
+ * @note This function will halt on the first NULL byte it finds in
+ * either string.
  */
-U32 strncmp(const char *a, const char *b, U32 n);
+bool streqn(const char *a, const char *b, U32 n);
 
-/** Order two strings.
+/** compare two strings for equality.
  *
- * This is equivalent to @a strncmp, with the maximum length being the
+ * This is equivalent to @a strneq, with the maximum length being the
  * length of the shortest input string.
  *
- * @see strncmp
+ * @see strneq
  */
-U32 strcmp(const char *a, const char *b);
+bool streq(const char *a, const char *b);
 
 /** Locate leftmost instance of character @a c in string @a s.

nxos/systems/tests/main.c

@@ -19 +19 @@
 
   //tests_all();
-  tests_usb();
+  //tests_usb();
   //tests_bt();
   //tests_usb_hardcore();

nxos/systems/tests/tests.c

@@ -4 +4 @@
 #include "base/interrupts.h"
 #include "base/display.h"
+#include "base/assert.h"
 #include "base/memmap.h"
 #include "base/util.h"
@@ -42 +43 @@
 }
 
+
+void tests_util(void) {
+  hello();
+
+  /* Simple equality. */
+  NX_ASSERT(streq("foo", "foo"));
+
+  /* Simple inequality. */
+  NX_ASSERT(!streq("foo", "bar"));
+  NX_ASSERT(!streq("bar", "foo"));
+
+  /* Inequality towards the end of the string. */
+  NX_ASSERT(!streq("foo", "fob"));
+  NX_ASSERT(!streq("fob", "foo"));
+
+  /* Inequality of different length strings. */
+  NX_ASSERT(!streq("foo", "foobar"));
+  NX_ASSERT(!streq("foobar", "foo"));
+
+  /* Inequality vs. the empty string. */
+  NX_ASSERT(!streq("foo", ""));
+  NX_ASSERT(!streq("", "foo"));
+
+  /* The border case of the empty string. */
+  NX_ASSERT(streq("", ""));
+
+
+  /* Simple equality. */
+  NX_ASSERT(streqn("foo", "foo", 3));
+
+  /* Simple inequality. */
+  NX_ASSERT(!streqn("foo", "bar", 3));
+  NX_ASSERT(!streqn("bar", "foo", 3));
+
+  /* Inequality towards the end of the string. */
+  NX_ASSERT(!streqn("foo", "fob", 3));
+  NX_ASSERT(!streqn("fob", "foo", 3));
+
+  /* Inequality of different length strings. */
+  NX_ASSERT(!streqn("foo", "foobar", 6));
+  NX_ASSERT(!streqn("foobar", "foo", 6));
+
+  /* Inequality vs. the empty string. */
+  NX_ASSERT(!streqn("foo", "", 3));
+  NX_ASSERT(!streqn("", "foo", 3));
+
+  /* Equality of the empty string, no matter the given length. */
+  NX_ASSERT(streqn("", "", 42));
+
+  /* Equality of unequal strings if length == 0 */
+  NX_ASSERT(streqn("bleh", "foo", 0));
+
+  /* Prefix equality of unequal strings */
+  NX_ASSERT(streqn("feh", "foo", 1));
+
+  goodbye();
+}
+
+
 void tests_display(void) {
   char buf[2] = { 0, 0 };
@@ -327 +387 @@
 }
 
-void tests_bt2(void)
-{
+void tests_bt2(void) {
   /*int i;
    */
@@ -387 +446 @@
 
 
-/* returns 1 if they are identic
- * 0 else
- *
- * TODO: use base/util.h:strncmp instead.
- */
-static U8 compare_str(char *str_a, char *str_b, U32 max)
-{
-
-  while (*str_a != '\0'
-         && *str_b != '\0'
-         && max > 0)
-    {
-      if (*str_a != *str_b) {
-        return 0;
-      }
-      str_a++;
-      str_b++;
-      max--;
-    }
-
-  if (*str_a != *str_b && max > 0) {
-    return 0;
-  }
-
-  return 1;
-}
-
-
 #define CMD_UNKNOWN    "Unknown"
 #define CMD_OK         "Ok"
@@ -426 +457 @@
  * @return 0 if success ; 1 if unknown command ; 2 if halt
  */
-static int tests_command(char *buffer, int lng)
-{
+static int tests_command(char *buffer) {
   int i;
   S32 t;
@@ -434 +464 @@
 
   i = 0;
-  if (compare_str(buffer, "motor", lng))
+  if (streq(buffer, "motor"))
     tests_motor();
-  else if (compare_str(buffer, "sound", lng))
+  else if (streq(buffer, "sound"))
     tests_sound();
-  else if (compare_str(buffer, "display", lng))
+  else if (streq(buffer, "util"))
+    tests_util();
+  else if (streq(buffer, "display"))
     tests_display();
-  else if (compare_str(buffer, "sysinfo", lng))
+  else if (streq(buffer, "sysinfo"))
     tests_sysinfo();
-  else if (compare_str(buffer, "sensors", lng))
+  else if (streq(buffer, "sensors"))
     tests_sensors();
-  else if (compare_str(buffer, "tachy", lng))
+  else if (streq(buffer, "tachy"))
     tests_tachy();
-  else if (compare_str(buffer, "radar", lng))
+  else if (streq(buffer, "radar"))
     tests_radar();
-  else if (compare_str(buffer, "bt", lng))
+  else if (streq(buffer, "bt"))
     tests_bt();
-  else if (compare_str(buffer, "bt2", lng))
+  else if (streq(buffer, "bt2"))
     tests_bt2();
-  else if (compare_str(buffer, "all", lng))
+  else if (streq(buffer, "all"))
     tests_all();
-  else if (compare_str(buffer, "halt", lng))
+  else if (streq(buffer, "halt"))
     return 2;
-  else if (compare_str(buffer, "Al", lng))
+  else if (streq(buffer, "Al"))
     nx_motors_rotate_angle(0, 90, 100, 1);
-  else if (compare_str(buffer, "Ar", lng))
+  else if (streq(buffer, "Ar"))
     nx_motors_rotate_angle(0, -90, 100, 1);
-  else if (compare_str(buffer, "Ac", lng)) {
+  else if (streq(buffer, "Ac")) {
     nx_motors_rotate(0, 75);
     while((t = nx_motors_get_tach_count(0)) != 0) {
@@ -473 +505 @@
     }
     nx_motors_stop(0, 1);
-  } else if (compare_str(buffer, "BCf", lng)) {
+  } else if (streq(buffer, "BCf")) {
     nx_motors_rotate(1, -100);
     nx_motors_rotate(2, -100);
@@ -479 +511 @@
     nx_motors_stop(1, 0);
     nx_motors_stop(2, 0);
-  } else if (compare_str(buffer, "BCr", lng)) {
+  } else if (streq(buffer, "BCr")) {
     nx_motors_rotate(1, 80);
     nx_motors_rotate(2, 80);
@@ -588 +620 @@
     /* Start interpreting */
 
-    i = tests_command(buffer, lng);
+    i = tests_command(buffer);
 
     nx_bt_stream_read((U8 *)&buffer, 2);
@@ -664 +696 @@
     /* Start interpreting */
 
-    i = tests_command(buffer, lng);
+    i = tests_command(buffer);
 
     if (i == 2) {
@@ -701 +733 @@
 
     if ( (lng = nx_usb_data_read()) > 0) {
-      if (compare_str(buffer, "halt", lng)) {
+      if (streq(buffer, "halt")) {
         break;
       }
@@ -769 +801 @@
   test_silent = TRUE;
 
+  tests_util();
   tests_display();
   tests_sound();

nxos/systems/tests/tests.h

@@ -2 +2 @@
 #define __NXOS_TESTS_H__
 
+void tests_util(void);
 void tests_motor(void);
 void tests_sound(void);