zstr.c (2963B)
1 /* See LICENSE file for copyright and license details. */ 2 #include "internals.h" 3 4 #include <stdio.h> 5 6 #define num libzahl_tmp_str_num 7 #define rem libzahl_tmp_str_rem 8 9 /* All 19 you see here is derived from that 10¹⁹ is the largest 10 * power of than < 2⁶⁴, and 64 is the number of bits in 11 * zahl_char_t. If zahl_char_t is chanced, the value 19, and 12 * the cast to unsigned long long must be changed accordingly. */ 13 14 15 #define S1(P) P"0" P"1" P"2" P"3" P"4" P"5" P"6" P"7" P"8" P"9" 16 #define S2(P) S1(P"0")S1(P"1")S1(P"2")S1(P"3")S1(P"4")S1(P"5")S1(P"6")S1(P"7")S1(P"8")S1(P"9") 17 18 19 static inline O2 void 20 sprintint_fix(char *buf, zahl_char_t v) 21 { 22 const char *partials = S2(""); 23 uint16_t *buffer = (uint16_t *)(buf + 1); 24 25 buffer[8] = *(const uint16_t *)(partials + 2 * (v % 100)), v /= 100; 26 buffer[7] = *(const uint16_t *)(partials + 2 * (v % 100)), v /= 100; 27 buffer[6] = *(const uint16_t *)(partials + 2 * (v % 100)), v /= 100; 28 buffer[5] = *(const uint16_t *)(partials + 2 * (v % 100)), v /= 100; 29 buffer[4] = *(const uint16_t *)(partials + 2 * (v % 100)), v /= 100; 30 buffer[3] = *(const uint16_t *)(partials + 2 * (v % 100)), v /= 100; 31 buffer[2] = *(const uint16_t *)(partials + 2 * (v % 100)), v /= 100; 32 buffer[1] = *(const uint16_t *)(partials + 2 * (v % 100)), v /= 100; 33 buffer[0] = *(const uint16_t *)(partials + 2 * (v % 100)), v /= 100; 34 *buf = (char)('0' + v); 35 buf[19] = 0; 36 } 37 38 static inline void 39 cmemmove(char *d, const char *s, long n) 40 { 41 while (n--) 42 *d++ = *s++; 43 } 44 45 static inline size_t 46 sprintint_min(char *buf, zahl_char_t v) 47 { 48 long i = 0, j; 49 sprintint_fix(buf, v); 50 for (; buf[i] == '0'; i++); 51 cmemmove(buf, buf + i, j = 19 - i); 52 buf[j] = 0; 53 return (size_t)j; 54 } 55 56 57 char * 58 zstr(z_t a, char *b, size_t n) 59 { 60 char buf[19 + 1]; 61 size_t len, neg, last, tot = 0; 62 char overridden = 0; 63 64 if (unlikely(zzero(a))) { 65 if (unlikely(!b) && unlikely(!(b = malloc(2)))) 66 libzahl_memfailure(); 67 b[0] = '0'; 68 b[1] = 0; 69 return b; 70 } 71 72 if (!n) { 73 /* Calculate a value that is at least the number of 74 * digits required to store the string. The overshoot 75 * is not too signicant. */ 76 n = (20 * BITS_PER_CHAR / 64 + (BITS_PER_CHAR == 8)) * a->used; 77 /* Note, depends on a ≠ as ensure above. */ 78 } 79 80 if (unlikely(!b) && unlikely(!(b = libzahl_temp_allocation = malloc(n + 1)))) 81 libzahl_memfailure(); 82 83 neg = znegative(a); 84 zabs(num, a); 85 b[0] = '-'; 86 b += neg; 87 n -= neg; 88 n = (last = n) > 19 ? (n - 19) : 0; 89 90 for (;;) { 91 zdivmod(num, rem, num, libzahl_const_1e19); 92 if (likely(!zzero(num))) { 93 sprintint_fix(b + n, zzero(rem) ? 0 : rem->chars[0]); 94 b[n + 19] = overridden; 95 overridden = b[n]; 96 n = (last = n) > 19 ? (n - 19) : 0; 97 tot += 19; 98 } else { 99 len = sprintint_min(buf, rem->chars[0]); 100 if (tot) { 101 memcpy(b, buf, len); 102 memmove(b + len, b + last, tot + 1); 103 } else { 104 memcpy(b, buf, len + 1); 105 } 106 break; 107 } 108 } 109 110 libzahl_temp_allocation = 0; 111 return b - neg; 112 }