This change adds support for wide strings (u16*) to printf() variants. This feature is used by a future change. Signed-off-by: Nikos Nikoleris <nikos.nikoleris@xxxxxxx> --- lib/printf.c | 101 ++++++++++++++++++++++++++++++++++++++++++++++++++- 1 file changed, 100 insertions(+), 1 deletion(-) diff --git a/lib/printf.c b/lib/printf.c index 724befa..14a3fed 100644 --- a/lib/printf.c +++ b/lib/printf.c @@ -57,6 +57,102 @@ static void print_str(pstream_t *p, const char *s, strprops_t props) } } +/* + * Adapted from drivers/firmware/efi/libstub/vsprintf.c + */ +static u32 utf16_to_utf32(const u16 **s16) +{ + u16 c0, c1; + + c0 = *(*s16)++; + /* not a surrogate */ + if ((c0 & 0xf800) != 0xd800) + return c0; + /* invalid: low surrogate instead of high */ + if (c0 & 0x0400) + return 0xfffd; + c1 = **s16; + /* invalid: missing low surrogate */ + if ((c1 & 0xfc00) != 0xdc00) + return 0xfffd; + /* valid surrogate pair */ + ++(*s16); + return (0x10000 - (0xd800 << 10) - 0xdc00) + (c0 << 10) + c1; +} + +/* + * Adapted from drivers/firmware/efi/libstub/vsprintf.c + */ +static size_t utf16s_utf8nlen(const u16 *s16, size_t maxlen) +{ + size_t len, clen; + + for (len = 0; len < maxlen && *s16; len += clen) { + u16 c0 = *s16++; + + /* First, get the length for a BMP character */ + clen = 1 + (c0 >= 0x80) + (c0 >= 0x800); + if (len + clen > maxlen) + break; + /* + * If this is a high surrogate, and we're already at maxlen, we + * can't include the character if it's a valid surrogate pair. + * Avoid accessing one extra word just to check if it's valid + * or not. + */ + if ((c0 & 0xfc00) == 0xd800) { + if (len + clen == maxlen) + break; + if ((*s16 & 0xfc00) == 0xdc00) { + ++s16; + ++clen; + } + } + } + + return len; +} + +/* + * Adapted from drivers/firmware/efi/libstub/vsprintf.c + */ +static void print_wstring(pstream_t *p, const u16 *s, strprops_t props) +{ + const u16 *ws = (const u16 *)s; + size_t pos = 0, size = p->remain + 1, len = utf16s_utf8nlen(ws, props.precision); + + while (len-- > 0) { + u32 c32 = utf16_to_utf32(&ws); + u8 *s8; + size_t clen; + + if (c32 < 0x80) { + addchar(p, c32); + continue; + } + + /* Number of trailing octets */ + clen = 1 + (c32 >= 0x800) + (c32 >= 0x10000); + + len -= clen; + s8 = (u8 *)(p->buffer - p->added + pos); + + /* Avoid writing partial character */ + addchar(p, '\0'); + pos += clen; + if (pos >= size) + continue; + + /* Set high bits of leading octet */ + *s8 = (0xf00 >> 1) >> clen; + /* Write trailing octets in reverse order */ + for (s8 += clen; clen; --clen, c32 >>= 6) + *s8-- = 0x80 | (c32 & 0x3f); + /* Set low bits of leading octet */ + *s8 |= c32; + } +} + static char digits[16] = "0123456789abcdef"; static void print_int(pstream_t *ps, long long n, int base, strprops_t props) @@ -302,7 +398,10 @@ int vsnprintf(char *buf, int size, const char *fmt, va_list va) print_unsigned(&s, (unsigned long)va_arg(args, void *), 16, props); break; case 's': - print_str(&s, va_arg(args, const char *), props); + if (nlong) + print_wstring(&s, va_arg(args, const u16 *), props); + else + print_str(&s, va_arg(args, const char *), props); break; default: addchar(&s, f); -- 2.25.1