diff options
| -rw-r--r-- | lib/vsprintf.c | 60 |
1 files changed, 33 insertions, 27 deletions
diff --git a/lib/vsprintf.c b/lib/vsprintf.c index 67e74cb..8cb7635 100644 --- a/lib/vsprintf.c +++ b/lib/vsprintf.c @@ -245,17 +245,32 @@ char *put_dec(char *buf, unsigned long long n) /* See comment in put_dec_full9 for choice of constants */ static noinline_for_stack -char *put_dec_full4(char *buf, unsigned q) +void put_dec_full4(char *buf, unsigned q) { unsigned r; r = (q * 0xccd) >> 15; - *buf++ = (q - 10 * r) + '0'; + buf[0] = (q - 10 * r) + '0'; q = (r * 0xcd) >> 11; - *buf++ = (r - 10 * q) + '0'; + buf[1] = (r - 10 * q) + '0'; r = (q * 0xcd) >> 11; - *buf++ = (q - 10 * r) + '0'; - *buf++ = r + '0'; - return buf; + buf[2] = (q - 10 * r) + '0'; + buf[3] = r + '0'; +} + +/* + * Call put_dec_full4 on x % 10000, return x / 10000. + * The approximation x/10000 == (x * 0x346DC5D7) >> 43 + * holds for all x < 1,128,869,999. The largest value this + * helper will ever be asked to convert is 1,125,520,955. + * (d1 in the put_dec code, assuming n is all-ones). + */ +static +unsigned put_dec_helper4(char *buf, unsigned x) +{ + uint32_t q = (x * (uint64_t)0x346DC5D7) >> 43; + + put_dec_full4(buf, x - q * 10000); + return q; } /* Based on code by Douglas W. Jones found at @@ -277,28 +292,19 @@ char *put_dec(char *buf, unsigned long long n) d3 = (h >> 16); /* implicit "& 0xffff" */ q = 656 * d3 + 7296 * d2 + 5536 * d1 + ((uint32_t)n & 0xffff); + q = put_dec_helper4(buf, q); + + q += 7671 * d3 + 9496 * d2 + 6 * d1; + q = put_dec_helper4(buf+4, q); + + q += 4749 * d3 + 42 * d2; + q = put_dec_helper4(buf+8, q); - buf = put_dec_full4(buf, q % 10000); - q = q / 10000; - - d1 = q + 7671 * d3 + 9496 * d2 + 6 * d1; - buf = put_dec_full4(buf, d1 % 10000); - q = d1 / 10000; - - d2 = q + 4749 * d3 + 42 * d2; - buf = put_dec_full4(buf, d2 % 10000); - q = d2 / 10000; - - d3 = q + 281 * d3; - if (!d3) - goto done; - buf = put_dec_full4(buf, d3 % 10000); - q = d3 / 10000; - if (!q) - goto done; - buf = put_dec_full4(buf, q); - done: - while (buf[-1] == '0') + q += 281 * d3; + buf += 12; + if (q) + buf = put_dec_trunc8(buf, q); + else while (buf[-1] == '0') --buf; return buf; |
