100 lines
1.9 KiB
C
100 lines
1.9 KiB
C
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#pragma once
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#include <stdint.h>
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#include <stddef.h>
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void *memcpy(void *restrict dest, const void *restrict src, size_t n)
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{
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unsigned char *d = dest;
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const unsigned char *s = src;
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for (; n; n--) *d++ = *s++;
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return dest;
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}
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void *memset(void *dest, int c, size_t n)
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{
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unsigned char *s = dest;
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size_t k;
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/* Fill head and tail with minimal branching. Each
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* conditional ensures that all the subsequently used
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* offsets are well-defined and in the dest region. */
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if (!n) return dest;
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s[0] = c;
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s[n-1] = c;
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if (n <= 2) return dest;
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s[1] = c;
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s[2] = c;
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s[n-2] = c;
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s[n-3] = c;
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if (n <= 6) return dest;
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s[3] = c;
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s[n-4] = c;
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if (n <= 8) return dest;
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/* Advance pointer to align it at a 4-byte boundary,
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* and truncate n to a multiple of 4. The previous code
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* already took care of any head/tail that get cut off
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* by the alignment. */
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k = -(uintptr_t)s & 3;
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s += k;
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n -= k;
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n &= -4;
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/* Pure C fallback with no aliasing violations. */
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for (; n; n--, s++) *s = c;
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return dest;
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}
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size_t strlen(const char *s)
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{
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const char *a = s;
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for (; *s; s++);
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return s-a;
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}
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int memcmp(const void *vl, const void *vr, size_t n)
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{
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const unsigned char *l=vl, *r=vr;
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for (; n && *l == *r; n--, l++, r++);
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return n ? *l-*r : 0;
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}
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char *strncpy(char *restrict d, const char *restrict s, size_t n)
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{
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for (; n && (*d=*s); n--, s++, d++);
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memset(d, 0, n);
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return d;
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}
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char *strcpy(char *restrict dest, const char *restrict src)
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{
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char *restrict d = dest;
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const char *restrict s = src;
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for (; (*d=*s); s++, d++);
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return d;
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}
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int strcmp(const char *l, const char *r)
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{
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for (; *l==*r && *l; l++, r++);
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return *(unsigned char *)l - *(unsigned char *)r;
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}
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/* STDLIB DIV FUNCTIONS */
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typedef struct { int quot, rem; } div_t;
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typedef struct { long quot, rem; } ldiv_t;
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div_t div(int num, int den)
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{
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return (div_t){ num/den, num%den };
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}
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ldiv_t ldiv(long num, long den)
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{
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return (ldiv_t){ num/den, num%den };
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}
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