Commit 9b9f7a00 authored by Zebediah Figura's avatar Zebediah Figura Committed by Alexandre Julliard

msvcrt: Perform a base-10 logarithm using integer math.

parent 8a25798e
...@@ -22,7 +22,7 @@ ...@@ -22,7 +22,7 @@
#define EXP_BITS 11 #define EXP_BITS 11
#define MANT_BITS 53 #define MANT_BITS 53
static const int p10s[] = { 1, 10, 100, 1000, 10000, 100000, 1000000, 10000000, 100000000 }; static const int p10s[] = { 1, 10, 100, 1000, 10000, 100000, 1000000, 10000000, 100000000, 1000000000 };
#define LIMB_DIGITS 9 /* each DWORD stores up to 9 digits */ #define LIMB_DIGITS 9 /* each DWORD stores up to 9 digits */
#define LIMB_MAX 1000000000 /* 10^9 */ #define LIMB_MAX 1000000000 /* 10^9 */
......
...@@ -135,6 +135,20 @@ static inline int mbstowcs_len(wchar_t *wcstr, const char *mbstr, ...@@ -135,6 +135,20 @@ static inline int mbstowcs_len(wchar_t *wcstr, const char *mbstr,
} }
return wlen; return wlen;
} }
static inline unsigned int log2i(unsigned int x)
{
ULONG result;
_BitScanReverse(&result, x);
return result;
}
static inline unsigned int log10i(unsigned int x)
{
unsigned int t = ((log2i(x) + 1) * 1233) / 4096;
return t - (x < p10s[t]);
}
#endif #endif
static inline int FUNC_NAME(pf_output_wstr)(FUNC_NAME(puts_clbk) pf_puts, void *puts_ctx, static inline int FUNC_NAME(pf_output_wstr)(FUNC_NAME(puts_clbk) pf_puts, void *puts_ctx,
...@@ -635,7 +649,7 @@ static inline int FUNC_NAME(pf_output_fp)(FUNC_NAME(puts_clbk) pf_puts, void *pu ...@@ -635,7 +649,7 @@ static inline int FUNC_NAME(pf_output_fp)(FUNC_NAME(puts_clbk) pf_puts, void *pu
if(!b->data[bnum_idx(b, b->e-1)]) if(!b->data[bnum_idx(b, b->e-1)])
first_limb_len = 1; first_limb_len = 1;
else else
first_limb_len = floor(log10(b->data[bnum_idx(b, b->e - 1)])) + 1; first_limb_len = log10i(b->data[bnum_idx(b, b->e - 1)]) + 1;
radix_pos = first_limb_len + LIMB_DIGITS + e10; radix_pos = first_limb_len + LIMB_DIGITS + e10;
round_pos = flags->Precision; round_pos = flags->Precision;
...@@ -700,7 +714,7 @@ static inline int FUNC_NAME(pf_output_fp)(FUNC_NAME(puts_clbk) pf_puts, void *pu ...@@ -700,7 +714,7 @@ static inline int FUNC_NAME(pf_output_fp)(FUNC_NAME(puts_clbk) pf_puts, void *pu
if(!b->data[bnum_idx(b, b->e-1)]) if(!b->data[bnum_idx(b, b->e-1)])
i = 1; i = 1;
else else
i = floor(log10(b->data[bnum_idx(b, b->e-1)])) + 1; i = log10i(b->data[bnum_idx(b, b->e-1)]) + 1;
if(i != first_limb_len) { if(i != first_limb_len) {
first_limb_len = i; first_limb_len = i;
radix_pos++; radix_pos++;
......
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