Messages in this thread | | | Date | Wed, 21 Apr 2004 15:22:28 +0100 | From | Matthew Wilcox <> | Subject | Re: [PATCH] add some EFI device smarts |
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On Wed, Apr 21, 2004 at 06:59:22AM -0600, Bjorn Helgaas wrote: > > > + /* Convert Unicode to normal chars */ > > > + for (i = 0; i < (name_size/sizeof(name_unicode[0])); i++) > > > + name_utf8[i] = name_unicode[i] & 0xff; > > > + name_utf8[i] = 0; > > > > I've never had a clear understanding of this. It's not really UTF8 > > (else straight ASCII text could be used), but more like UCS2. > > I don't understand Unicode either. Maybe the attached is a little > closer? The EFI spec (1.10, table 2-2) says strings are stored in > UTF-16, and I think that UTF-16 is the same as ASCII for > (0 < c <= 0x7f).
Ah, I know this one ...
UTF-16 is like UCS-2 except that it has escapes to let you use past the first plane of Unicode. That is, by and large it's 2-bytes long, but sometimes it can be 4 or more bytes long. How to convert? Let's see ...
for (i = 0, j = 0; i < (name_size/sizeof(name_unicode[0])); i++) { unsigned int rune = name_unicode[i]; if (0xD7FF < rune && rune < 0xE000) { rune = (rune & 0x7ff) << 10; rune |= name_unicode[++i] & 0x3ff; } if (rune < 0x80) { name_utf8[j++] = rune; } else if (rune < 0x800) { name_utf8[j++] = 0xc0 | (rune >> 6); name_utf8[j++] = 0x80 | (rune & 0x3f); } else if (rune < 0x10000) { name_utf8[j++] = 0xe0 | (rune >> 12); name_utf8[j++] = 0x80 | ((rune >> 6) & 0x3f); name_utf8[j++] = 0x80 | (rune & 0x3f); } else { name_utf8[j++] = 0xf0 | (rune >> 18); name_utf8[j++] = 0x80 | ((rune >> 12) & 0x3f); name_utf8[j++] = 0x80 | ((rune >> 6) & 0x3f); name_utf8[j++] = 0x80 | (rune & 0x3f); } }
ftp://ftp.rfc-editor.org/in-notes/rfc2279.txt ftp://ftp.rfc-editor.org/in-notes/rfc2781.txt
Haven't even tried to compile it ...
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