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#include "fmt.h"
size_t fmt_utf8(char *dest,uint32_t n) {
size_t i,j;
if (n<=0x7f) {
if (dest) *dest=(char)n;
return 1;
}
for (i=0x3f,j=1; i<=0x7fffffff; i=(i<<5)|0x1f, ++j) {
if (i>=n) {
--j;
if (dest) {
size_t k=j*6;
// gcc -fanalyze warns here that j-1 might underflow, leading to
// undefined behavior because right shift by more than integer
// width is undefined. That can't happen because both n>0x7f and
// i>=n would have to be true and we initialize i as 0x3f and
// with each iteration j is incremented. It's a false positive.
*dest++=(char)(((char)0xc0 >> (j-1)) | (char)(n >> k));
while (k) {
*dest++=(char)(0x80 | ((n >> (k-6)) & 0x3f));
k-=6;
}
}
return j+1;
}
if (i==0x7fffffff) return 0;
}
/* we were asked to encode a value that cannot be encoded */
return 0;
}
/* unit tested via scan/scan_utf8.c */
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