Changeset dcb74c0a in mainline for uspace/lib/c

Timestamp:

2011-07-03T10:05:21Z (14 years ago)

Author:

Jiri Svoboda <jiri@…>

Branches:

lfn, master, serial, ticket/834-toolchain-update, topic/msim-upgrade, topic/simplify-dev-export

Children:

64e6945d

Parents:

8e1a819

Message:

Add function to str.c to convert space-padded ASCII to standard string
representation. Use for decoding SCSI strings.

Location:

uspace/lib/c

Files:

• generic/str.c (modified) (1 diff)
• include/str.h (modified) (2 diffs)

uspace/lib/c/generic/str.c

@@ -544 +544 @@
         
         str_cpy(dest + dstr_size, size - dstr_size, src);
+}
+
+/** Convert space-padded ASCII to string.
+ *
+ * Common legacy text encoding in hardware is 7-bit ASCII fitted into
+ * a fixed-with byte buffer (bit 7 always zero), right-padded with spaces
+ * (ASCII 0x20). Convert space-padded ascii to string representation.
+ *
+ * If the text does not fit into the destination buffer, the function converts
+ * as many characters as possible and returns EOVERFLOW.
+ *
+ * If the text contains non-ASCII bytes (with bit 7 set), the whole string is
+ * converted anyway and invalid characters are replaced with question marks
+ * (U_SPECIAL) and the function returns EIO.
+ *
+ * Regardless of return value upon return @a dest will always be well-formed.
+ *
+ * @param dest          Destination buffer
+ * @param size          Size of destination buffer
+ * @param src           Space-padded ASCII.
+ * @param n             Size of the source buffer in bytes.
+ *
+ * @return              EOK on success, EOVERFLOW if the text does not fit
+ *                      destination buffer, EIO if the text contains
+ *                      non-ASCII bytes.
+ */
+int spascii_to_str(char *dest, size_t size, const uint8_t *src, size_t n)
+{
+        size_t sidx;
+        size_t didx;
+        size_t dlast;
+        uint8_t byte;
+        int rc;
+        int result;
+
+        /* There must be space for a null terminator in the buffer. */
+        assert(size > 0);
+        result = EOK;
+
+        didx = 0;
+        dlast = 0;
+        for (sidx = 0; sidx < n; ++sidx) {
+                byte = src[sidx];
+                if (!ascii_check(byte)) {
+                        byte = U_SPECIAL;
+                        result = EIO;
+                }
+
+                rc = chr_encode(byte, dest, &didx, size - 1);
+                if (rc != EOK) {
+                        assert(rc == EOVERFLOW);
+                        dest[didx] = '\0';
+                        return rc;
+                }
+
+                /* Remember dest index after last non-empty character */
+                if (byte != 0x20)
+                        dlast = didx;
+        }
+
+        /* Terminate string after last non-empty character */
+        dest[dlast] = '\0';
+        return result;
 }
 

uspace/lib/c/include/str.h

@@ -48 +48 @@
 #define STR_BOUNDS(length)  ((length) << 2)
 
+/**
+ * Maximum size of a buffer needed to a string converted from space-padded
+ * ASCII of size @a spa_size using spascii_to_str().
+ */
+#define SPASCII_STR_BUFSIZE(spa_size) ((spa_size) + 1)
+
 extern wchar_t str_decode(const char *str, size_t *offset, size_t sz);
 extern int chr_encode(const wchar_t ch, char *str, size_t *offset, size_t sz);
@@ -73 +79 @@
 extern void str_append(char *dest, size_t size, const char *src);
 
+extern int spascii_to_str(char *dest, size_t size, const uint8_t *src, size_t n);
 extern void wstr_to_str(char *dest, size_t size, const wchar_t *src);
 extern char *wstr_to_astr(const wchar_t *src);