8bb03da90
Denys Vlasenko
2021-07-02
Subject
awk: rand() could return 1.0, fix this - should be in [0,1)
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editors/awk.c+13 -2
| @@ -3118,9 +3118,20 @@ static var *evaluate(node *op, var *res) | |
| case F_rn: /*rand*/ | |
| if (op1) | |
| syntax_error("Too many arguments"); | |
| - | R_d = (double)rand() / (double)RAND_MAX; |
| + | { |
| + | #if RAND_MAX >= 0x7fffffff |
| + | uint32_t u = ((uint32_t)rand() << 16) ^ rand(); |
| + | uint64_t v = ((uint64_t)rand() << 32) | u; |
| + | /* the above shift+or is optimized out on 32-bit arches */ |
| + | # if RAND_MAX > 0x7fffffff |
| + | v &= 0x7fffffffffffffffUL; |
| + | # endif |
| + | R_d = (double)v / 0x8000000000000000UL; |
| + | #else |
| + | # error Not implemented for this value of RAND_MAX |
| + | #endif |
| break; | |
| - | |
| + | } |
| case F_co: | |
| if (ENABLE_FEATURE_AWK_LIBM) { | |
| R_d = cos(L_d); | |