diff options
Diffstat (limited to 'erts/emulator/sys/common/erl_sys_common_misc.c')
| -rw-r--r-- | erts/emulator/sys/common/erl_sys_common_misc.c | 104 |
1 files changed, 55 insertions, 49 deletions
diff --git a/erts/emulator/sys/common/erl_sys_common_misc.c b/erts/emulator/sys/common/erl_sys_common_misc.c index 79f87eb3a9..ba03a11405 100644 --- a/erts/emulator/sys/common/erl_sys_common_misc.c +++ b/erts/emulator/sys/common/erl_sys_common_misc.c @@ -158,59 +158,50 @@ int sys_double_to_chars_fast(double f, char *buffer, int buffer_size, int decimals, int compact) { - /* Note that some C compilers don't support "static const" propagation - * so we use a defines */ - #define SYS_DOUBLE_RND_CONST 0.55555555555555555 + #define SYS_DOUBLE_RND_CONST 0.5 #define FRAC_SIZE 52 #define EXP_SIZE 11 - #define EXP_MASK ((1ll << EXP_SIZE) - 1) + #define EXP_MASK (((Uint64)1 << EXP_SIZE) - 1) #define MAX_DECIMALS (sizeof(cs_sys_double_pow10) \ / sizeof(cs_sys_double_pow10[0])) - #define FRAC_MASK ((1ll << FRAC_SIZE) - 1) - #define FRAC_MASK2 ((1ll << (FRAC_SIZE + 1)) - 1) - #define MAX_FLOAT (1ll << (FRAC_SIZE+1)) + #define FRAC_MASK (((Uint64)1 << FRAC_SIZE) - 1) + #define FRAC_MASK2 (((Uint64)1 << (FRAC_SIZE + 1)) - 1) + #define MAX_FLOAT ((Uint64)1 << (FRAC_SIZE+1)) static const double cs_sys_double_pow10[] = { - SYS_DOUBLE_RND_CONST / 1ll, - SYS_DOUBLE_RND_CONST / 10ll, - SYS_DOUBLE_RND_CONST / 100ll, - SYS_DOUBLE_RND_CONST / 1000ll, - SYS_DOUBLE_RND_CONST / 10000ll, - SYS_DOUBLE_RND_CONST / 100000ll, - SYS_DOUBLE_RND_CONST / 1000000ll, - SYS_DOUBLE_RND_CONST / 10000000ll, - SYS_DOUBLE_RND_CONST / 100000000ll, - SYS_DOUBLE_RND_CONST / 1000000000ll, - SYS_DOUBLE_RND_CONST / 10000000000ll, - SYS_DOUBLE_RND_CONST / 100000000000ll, - SYS_DOUBLE_RND_CONST / 1000000000000ll, - SYS_DOUBLE_RND_CONST / 10000000000000ll, - SYS_DOUBLE_RND_CONST / 100000000000000ll, - SYS_DOUBLE_RND_CONST / 1000000000000000ll, - SYS_DOUBLE_RND_CONST / 10000000000000000ll, - SYS_DOUBLE_RND_CONST / 100000000000000000ll, - SYS_DOUBLE_RND_CONST / 1000000000000000000ll + SYS_DOUBLE_RND_CONST / 1e0, + SYS_DOUBLE_RND_CONST / 1e1, + SYS_DOUBLE_RND_CONST / 1e2, + SYS_DOUBLE_RND_CONST / 1e3, + SYS_DOUBLE_RND_CONST / 1e4, + SYS_DOUBLE_RND_CONST / 1e5, + SYS_DOUBLE_RND_CONST / 1e6, + SYS_DOUBLE_RND_CONST / 1e7, + SYS_DOUBLE_RND_CONST / 1e8, + SYS_DOUBLE_RND_CONST / 1e9, + SYS_DOUBLE_RND_CONST / 1e10, + SYS_DOUBLE_RND_CONST / 1e11, + SYS_DOUBLE_RND_CONST / 1e12, + SYS_DOUBLE_RND_CONST / 1e13, + SYS_DOUBLE_RND_CONST / 1e14, + SYS_DOUBLE_RND_CONST / 1e15, + SYS_DOUBLE_RND_CONST / 1e16, + SYS_DOUBLE_RND_CONST / 1e17, + SYS_DOUBLE_RND_CONST / 1e18 }; - long long mantissa, int_part = 0, frac_part = 0; - short exp; + Uint64 mantissa, int_part, frac_part; + int exp; + int fbits; int max; int neg; double fr; - union { long long L; double F; } x; + union { Uint64 L; double F; } x; char *p = buffer; if (decimals < 0) return -1; - /* Round the number to given decimal places. The number of 5's in the - * SYS_DOUBLE_RND_CONST constant is chosen such that adding any more 5's doesn't - * change the double precision of the number, i.e.: - * 1> term_to_binary(0.55555555555555555, [{minor_version, 1}]). - * <<131,70,63,225,199,28,113,199,28,114>> - * 2> term_to_binary(0.5555555555555555555, [{minor_version, 1}]). - * <<131,70,63,225,199,28,113,199,28,114>> - */ if (f >= 0) { neg = 0; fr = decimals < MAX_DECIMALS ? (f + cs_sys_double_pow10[decimals]) : f; @@ -241,7 +232,7 @@ sys_double_to_chars_fast(double f, char *buffer, int buffer_size, int decimals, } exp -= EXP_MASK >> 1; - mantissa |= (1ll << FRAC_SIZE); + mantissa |= ((Uint64)1 << FRAC_SIZE); /* Don't bother with optimizing too large numbers or too large precision */ if (x.F > MAX_FLOAT || decimals >= MAX_DECIMALS) { @@ -256,11 +247,16 @@ sys_double_to_chars_fast(double f, char *buffer, int buffer_size, int decimals, return p - buffer; } else if (exp >= FRAC_SIZE) { int_part = mantissa << (exp - FRAC_SIZE); + frac_part = 0; + fbits = FRAC_SIZE; /* not important as frac_part==0 */ } else if (exp >= 0) { - int_part = mantissa >> (FRAC_SIZE - exp); - frac_part = (mantissa << (exp + 1)) & FRAC_MASK2; + fbits = FRAC_SIZE - exp; + int_part = mantissa >> fbits; + frac_part = mantissa & (((Uint64)1 << fbits) -1); } else /* if (exp < 0) */ { - frac_part = (mantissa & FRAC_MASK2) >> -(exp + 1); + int_part = 0; + frac_part = mantissa; + fbits = FRAC_SIZE - exp; } if (!int_part) { @@ -270,9 +266,8 @@ sys_double_to_chars_fast(double f, char *buffer, int buffer_size, int decimals, } else { int ret, i, n; while (int_part != 0) { - long long j = int_part / 10; - *p++ = (char)(int_part - ((j << 3) + (j << 1)) + '0'); - int_part = j; + *p++ = (char)((int_part % 10) + '0'); + int_part /= 10; } if (neg) *p++ = '-'; @@ -298,11 +293,22 @@ sys_double_to_chars_fast(double f, char *buffer, int buffer_size, int decimals, max = decimals; for (i = 0; i < max; i++) { - /* frac_part *= 10; */ - frac_part = (frac_part << 3) + (frac_part << 1); - - *p++ = (char)((frac_part >> (FRAC_SIZE + 1)) + '0'); - frac_part &= FRAC_MASK2; + if (frac_part > (ERTS_UINT64_MAX/5)) { + frac_part >>= 3; + fbits -= 3; + } + + /* Multiply by 10 (5*2) to extract decimal digit as integer part */ + frac_part *= 5; + fbits--; + + if (fbits >= 64) { + *p++ = '0'; + } + else { + *p++ = (char)((frac_part >> fbits) + '0'); + frac_part &= ((Uint64)1 << fbits) - 1; + } } /* Delete trailing zeroes */ |