restartable c16 <-> mb conversions

This commit is contained in:
bumbread 2022-07-16 04:33:55 +11:00
parent 7a1ffc534b
commit bf428a9924
4 changed files with 66 additions and 70 deletions

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@ -34,6 +34,8 @@ typedef struct lldiv_t {
#define EXIT_SUCCESS 0
#define RAND_MAX 65536
#define MB_LEN_MAX 4
#define MB_CUR_MAX 4
// Microsoft extension, COUNTOF(x) counts array elements

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@ -9,7 +9,10 @@ typedef uint_least32_t char32_t;
typedef struct mbstate_t mbstate_t;
struct mbstate_t {
union {
char16_t leftover;
char16_t high_surrogate;
}
};
size_t mbrtoc16(

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@ -2,7 +2,8 @@
#include <uchar.h>
#include <errno.h>
#include <unicode.h>
#include <unicope.h>
size_t mbrtoc16(
char16_t *restrict pc16,
@ -10,93 +11,83 @@ size_t mbrtoc16(
size_t n,
mbstate_t *restrict ps
) {
// Figure out the conversion state
static mbstate_t static_mbstate = {0};
if(ps == NULL) ps = &static_mbstate;
if(s == NULL) {
*ps = (mbstate_t) {0};
*ps = (mbstate_t) {0xd800};
return 0;
}
// First check leftovers, using 0xd800 as marker because it doesn't
// encode a valid character.
if(ps->leftover != 0xd800) {
// Check leftovers, using 0xd800 as "no leftover" marker because it
// doesn't encode a valid character.
if(ps->leftover == 0xd800) {
// Decode the UTF-8 encoded codepoint
char32_t code_point;
int mblen = utf8_chdec((char8_t *)s, n, &code_point);
if(mblen == UNI_ESTRLN) return (size_t)(-2);
if(mblen <= 0) goto invalid_seq;
// Encode the codepoint into UTF-16 string
char16_t str[2];
int c16len = utf16_chenc(str, 2, code_point);
if(c16len <= 0) goto invalid_seq;
// Assign the decoded UTF-16 character, decide leftover
if(pc16 != NULL) *pc16 = str[0];
ps->leftover = (c16len == 2? str[1] : 0xd800);
return (size_t)mblen;
}
else {
// Otherwise use and reset the leftover
if(pc16 != NULL) *pc16 = ps->leftover;
ps->leftover = 0xd800;
return (size_t)(-3);
}
else {
uchar_t ch;
char16_t str[3];
int chlen = utf8_dec(s, &ch);
if(chlen <= 0) goto encoding_error;
int wrlen = utf16_enc(str, ch);
char16_t curc;
char16_t next;
if(wrlen <= 0) goto encoding_error;
else if(wrlen == 2) {
curc = str[0];
next = 0xd800;
}
else {
curc = str[0];
next = str[1];
}
ps->leftover = next;
if(pc16 != NULL) *pc16 = curc;
return (size_t)-2;
}
encoding_error:
invalid_seq:
errno = EILSEQ;
return (size_t)(-1);
}
size_t c16rtomb(
char *restrict s,
char16_t c16,
mbstate_t *restrict ps
) {
// Figure out conversion state
static mbstate_t static_mbstate = {0};
if(ps == NULL) ps = &static_mbstate;
if(s == NULL) {
*ps = (mbstate_t) {0};
*ps = (mbstate_t) {0xd800};
return 0;
}
unsigned cp;
// High surrogate (save)
if(0xd800 <= c16 && c16 < 0xdc00) {
ps->leftover = c16;
char32_t codepoint_to_write;
// Check whether a high surrogate was detected in a previous call to the
// function. If not, the high_surrogate value is 0xd800
if(ps->high_surrogate == 0xd800) {
// If c16 is a surrogate record it, or throw an error
if(uni_is_hsur(c16)) {
ps->high_surrogate = c16;
return 0;
}
// Low surrogate (parse)
else if(0xdc00 <= c16 && c16 < 0xe000) {
if(ps->leftover == 0) goto encoding_error;
cp = ((ps->leftover & 0x3ff) << 10) | (c16 & 0x3ff);
else if(uni_is_lsur(c16)) {
goto invalid_char;
}
// Other char
else {
cp = c16;
// We'll just write c16
codepoint_to_write = c16;
}
size_t nbytes = 4;
if(cp < 0x10000) nbytes = 3;
if(cp < 0x800) nbytes = 2;
if(cp < 0x80) nbytes = 1;
switch(nbytes) {
case 1: {
s[0] = cp;
} break;
case 2: {
s[0] = 0xc0 | (cp >> 6);
s[1] = 0x80 | ((cp >> 0) & 0x3f);
} break;
case 3: {
s[0] = 0xe0 | (cp >> 12);
s[1] = 0x80 | ((cp >> 6) & 0x3f);
s[2] = 0x80 | ((cp >> 0) & 0x3f);
} break;
case 4: {
s[0] = 0xf0 | (cp >> 18);
s[1] = 0x80 | ((cp >> 12) & 0x3f);
s[2] = 0x80 | ((cp >> 6) & 0x3f);
s[3] = 0x80 | ((cp >> 0) & 0x3f);
} break;
// If high surrogate exists, the next character must be a low surrogate
// so we'll write a codepoint made out of high and low surrogates
else if(uni_is_lsur(c16)) {
codepoint_to_write = uni_surtoc(ps->high_surrogate, c16);
}
return nbytes;
encoding_error:
else goto invalid_char;
// Write the codepoint that we decided to write to multibyte string
int written_len = utf8_chenc(s, 4, codepoint_to_write);
if(written_len < 0) {
goto invalid_char;
}
return (size_t)written_len;
invalid_char:
errno = EILSEQ;
return (size_t)(-1);
}

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@ -2,7 +2,7 @@
#include <wctype.h>
#include <string.h>
#include <unicode.h>
#include <unicope.h>
int iswctype(wint_t wc, wctype_t desc) {
return desc(wc);
@ -113,9 +113,9 @@ int iswxdigit(wint_t wc) {
}
wint_t towlower(wint_t wc) {
return uni_to_lower(wc);
return uni_tolower(wc);
}
wint_t towupper(wint_t wc) {
return uni_to_upper(wc);
return uni_toupper(wc);
}