compressed errno strings (saving 209 bytes)

Author: ZERICO2005

src/libc/errno_str.c

@@ -0,0 +1,140 @@
+#include <errno.h>
+#include <stdio.h>
+#include <string.h>
+#include <ti/sprintf.h>
+
+static constexpr char errno_strings[] = {
+    "no error"
+    "\0" "EPERM"
+    "\0" "EINVAL"
+    "\0" "EIO"
+    "\0" "EDOM"
+    "\0" "ERANGE"
+    "\0" "EILSEQ"
+    /* C++ errno */
+    "\0" "E2BIG"
+    "\0" "EACCES"
+    "\0" "EADDRINUSE"
+    "\0" "EADDRNOTAVAIL"
+    "\0" "EAFNOSUPPORT"
+    "\0" "EAGAIN"
+    "\0" "EALREADY"
+    "\0" "EBADF"
+    "\0" "EBADMSG"
+    "\0" "EBUSY"
+    "\0" "ECANCELED"
+    "\0" "ECHILD"
+    "\0" "ECONNABORTED"
+    "\0" "ECONNREFUSED"
+    "\0" "ECONNRESET"
+    "\0" "EDEADLK"
+    "\0" "EDESTADDRREQ"
+    "\0" "EEXIST"
+    "\0" "EFAULT"
+    "\0" "EFBIG"
+    "\0" "EHOSTUNREACH"
+    "\0" "EIDRM"
+    "\0" "EINPROGRESS"
+    "\0" "EINTR"
+    "\0" "EISCONN"
+    "\0" "EISDIR"
+    "\0" "ELOOP"
+    "\0" "EMFILE"
+    "\0" "EMLINK"
+    "\0" "EMSGSIZE"
+    "\0" "ENAMETOOLONG"
+    "\0" "ENETDOWN"
+    "\0" "ENETRESET"
+    "\0" "ENETUNREACH"
+    "\0" "ENFILE"
+    "\0" "ENOBUFS"
+    "\0" "ENODATA"
+    "\0" "ENODEV"
+    "\0" "ENOENT"
+    "\0" "ENOEXEC"
+    "\0" "ENOLCK"
+    "\0" "ENOLINK"
+    "\0" "ENOMEM"
+    "\0" "ENOMSG"
+    "\0" "ENOPROTOOPT"
+    "\0" "ENOSPC"
+    "\0" "ENOSR"
+    "\0" "ENOSTR"
+    "\0" "ENOSYS"
+    "\0" "ENOTCONN"
+    "\0" "ENOTDIR"
+    "\0" "ENOTEMPTY"
+    "\0" "ENOTRECOVERABLE"
+    "\0" "ENOTSOCK"
+    "\0" "ENOTSUP"
+    "\0" "ENOTTY"
+    "\0" "ENXIO"
+    "\0" "EOPNOTSUPP"
+    "\0" "EOVERFLOW"
+    "\0" "EOWNERDEAD"
+    "\0" "EPIPE"
+    "\0" "EPROTO"
+    "\0" "EPROTONOSUPPORT"
+    "\0" "EPROTOTYPE"
+    "\0" "EROFS"
+    "\0" "ESPIPE"
+    "\0" "ESRCH"
+    "\0" "ETIME"
+    "\0" "ETIMEDOUT"
+    "\0" "ETXTBSY"
+    "\0" "EWOULDBLOCK"
+    "\0" "EXDEV"
+};
+
+static constexpr size_t count_errno_strings(const char *str, size_t size)
+{
+    size_t count = 0;
+    for (size_t i = 0; i < size; i++) {
+        if (str[i] == '\0') {
+            ++count;
+        }
+    }
+    return count;
+}
+
+static constexpr int errno_strings_count = count_errno_strings(errno_strings, sizeof(errno_strings));
+
+static constexpr size_t unknown_errno_number_offset = 14;
+#define UNKNOWN_ERRNO_STRING "unknown error -8388608"
+static char unknown_errno_string[] = UNKNOWN_ERRNO_STRING;
+
+static_assert(
+    UNKNOWN_ERRNO_STRING[unknown_errno_number_offset + 0] == '-' &&
+    UNKNOWN_ERRNO_STRING[unknown_errno_number_offset + 8] == '\0',
+    "the string for unknown errno numbers has been changed"
+);
+
+char *strerror(int errnum)
+{
+    if (errnum < 0 || errnum >= errno_strings_count) {
+        boot_sprintf(&unknown_errno_string[unknown_errno_number_offset], "%d", errnum);
+        return const_cast<char*>(unknown_errno_string);
+    }
+    const char* ret = errno_strings;
+    // worst case retrieval takes ~0.8ms (79 strings)
+    for (int i = 0; i < errnum; i++) {
+        // skips to the start of the next string
+        ret += strlen(ret) + 1;
+    }
+    return const_cast<char*>(ret);
+}
+
+void perror(const char *str)
+{
+    /* Normally this would print to stderr, but since they are handled the same and pulling */
+    /* in fputs would create a dependency on fileioc, just use puts rather than fputs here */
+
+    if (str != nullptr && *str != '\0') {
+        while (*str) {
+            putchar(*str++);
+        }
+        putchar(':');
+        putchar(' ');
+    }
+    puts(strerror(errno));
+}