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usb.core.Device: fix trailing NUL on e.g., product string

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.. and simplify the code to use vstr_add_char.
This commit is contained in:
Jeff Epler 2023-07-11 10:51:41 -05:00
parent 843ea86978
commit 6174e585af
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GPG Key ID: D5BF15AB975AB4DE
1 changed files with 34 additions and 45 deletions
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79
shared-module/usb/utf16le.c
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@ -26,60 +26,49 @@
#include "shared-module/usb/utf16le.h"
STATIC void _convert_utf16le_to_utf8(const uint16_t *utf16, size_t utf16_len, uint8_t *utf8, size_t utf8_len) {
// TODO: Check for runover.
(void)utf8_len;
typedef struct {
const uint16_t *buf;
size_t len;
} utf16_str;
for (size_t i = 0; i < utf16_len; i++) {
uint16_t chr = utf16[i];
if (chr < 0x80) {
*utf8++ = chr & 0xff;
} else if (chr < 0x800) {
*utf8++ = (uint8_t)(0xC0 | (chr >> 6 & 0x1F));
*utf8++ = (uint8_t)(0x80 | (chr >> 0 & 0x3F));
} else if (chr < 0x10000) {
// TODO: Verify surrogate.
*utf8++ = (uint8_t)(0xE0 | (chr >> 12 & 0x0F));
*utf8++ = (uint8_t)(0x80 | (chr >> 6 & 0x3F));
*utf8++ = (uint8_t)(0x80 | (chr >> 0 & 0x3F));
} else {
// TODO: Handle UTF-16 code points that take two entries.
uint32_t hc = ((chr & 0xFFFF0000) - 0xD8000000) >> 6; /* Get high 10 bits */
chr = (chr & 0xFFFF) - 0xDC00; /* Get low 10 bits */
chr = (hc | chr) + 0x10000;
*utf8++ = (uint8_t)(0xF0 | (chr >> 18 & 0x07));
*utf8++ = (uint8_t)(0x80 | (chr >> 12 & 0x3F));
*utf8++ = (uint8_t)(0x80 | (chr >> 6 & 0x3F));
*utf8++ = (uint8_t)(0x80 | (chr >> 0 & 0x3F));
}
STATIC uint32_t utf16str_peek_unit(utf16_str *utf) {
if (!utf->len) {
return 0;
}
return *utf->buf;
}
// Count how many bytes a utf-16-le encoded string will take in utf-8.
STATIC mp_int_t _count_utf8_bytes(const uint16_t *buf, size_t len) {
size_t total_bytes = 0;
for (size_t i = 0; i < len; i++) {
uint16_t chr = buf[i];
if (chr < 0x80) {
total_bytes += 1;
} else if (chr < 0x800) {
total_bytes += 2;
} else if (chr < 0x10000) {
total_bytes += 3;
} else {
total_bytes += 4;
STATIC uint32_t utf16str_next_unit(utf16_str *utf) {
uint32_t result = utf16str_peek_unit(utf);
if (utf->len) {
utf->len--;
utf->buf++;
}
return result;
}
STATIC uint32_t utf16str_next_codepoint(utf16_str *utf) {
uint32_t unichr = utf16str_next_unit(utf);
if (unichr >= 0xd800 && unichr < 0xdc00) {
uint32_t low_surrogate = utf16str_peek_unit(utf);
if (low_surrogate >= 0xdc00 && low_surrogate < 0xe000) {
(void)utf16str_next_unit(utf);
unichr = (unichr - 0xd800) * 0x400 + low_surrogate - 0xdc00 + 0x10000;
}
}
return total_bytes;
return unichr;
}
STATIC void _convert_utf16le_to_utf8(vstr_t *vstr, utf16_str *utf) {
while (utf->len) {
vstr_add_char(vstr, utf16str_next_codepoint(utf));
}
}
mp_obj_t utf16le_to_string(const uint16_t *buf, size_t utf16_len) {
size_t size = _count_utf8_bytes(buf, utf16_len);
// will grow if necessary, but will never grow for an all-ASCII descriptor
vstr_t vstr;
vstr_init_len(&vstr, size + 1);
byte *p = (byte *)vstr.buf;
// Null terminate.
p[size] = '\0';
_convert_utf16le_to_utf8(buf, utf16_len, p, size);
vstr_init(&vstr, utf16_len);
utf16_str utf = {buf, utf16_len};
_convert_utf16le_to_utf8(&vstr, &utf);
return mp_obj_new_str_from_vstr(&mp_type_str, &vstr);
}