From e5a50e19278acc1bd33db7651d07fb8e6adb988c Mon Sep 17 00:00:00 2001 From: "serg@serg.mylan" <> Date: Thu, 31 Mar 2005 17:46:36 +0200 Subject: [PATCH] decimal_div bug#9501 --- mysql-test/r/type_newdecimal.result | 3 + mysql-test/t/type_newdecimal.test | 7 +- strings/decimal.c | 123 +++++++++++++--------------- 3 files changed, 64 insertions(+), 69 deletions(-) diff --git a/mysql-test/r/type_newdecimal.result b/mysql-test/r/type_newdecimal.result index 315b009312d..330caf68293 100644 --- a/mysql-test/r/type_newdecimal.result +++ b/mysql-test/r/type_newdecimal.result @@ -839,3 +839,6 @@ Error 1365 Division by 0 INSERT INTO Sow6_2f VALUES ('a59b'); ERROR HY000: Incorrect decimal value: 'a59b' for column 'col1' at row 1 drop table Sow6_2f; +select 10.3330000000000/12.34500000; +10.3330000000000/12.34500000 +0.8370190360469825840421223160000 diff --git a/mysql-test/t/type_newdecimal.test b/mysql-test/t/type_newdecimal.test index f14e024adf0..e85cc3d55c6 100644 --- a/mysql-test/t/type_newdecimal.test +++ b/mysql-test/t/type_newdecimal.test @@ -748,7 +748,7 @@ select 1 / 0; #+-------+ #| 1 / 0 | #+-------+ -#| NULL | +#| NULL | #+-------+ #1 row in set, 1 warning (0.00 sec) # @@ -864,3 +864,8 @@ SELECT MOD(col1,0) FROM Sow6_2f; INSERT INTO Sow6_2f VALUES ('a59b'); #-- should return SQLSTATE 22018 invalid character value for cast drop table Sow6_2f; + +# +# bug#9501 +# +select 10.3330000000000/12.34500000; diff --git a/strings/decimal.c b/strings/decimal.c index d7bea3e291d..56dba61d887 100644 --- a/strings/decimal.c +++ b/strings/decimal.c @@ -1933,16 +1933,16 @@ int decimal_mul(decimal_t *from1, decimal_t *from2, decimal_t *to) XXX if this library is to be used with huge numbers of thousands of digits, fast division must be implemented and alloca should be changed to malloc (or at least fallback to malloc if alloca() fails) - but then, decimal_mod() should be rewritten too :( + but then, decimal_mul() should be rewritten too :( */ static int do_div_mod(decimal_t *from1, decimal_t *from2, decimal_t *to, decimal_t *mod, int scale_incr) { int frac1=ROUND_UP(from1->frac)*DIG_PER_DEC1, prec1=from1->intg+frac1, frac2=ROUND_UP(from2->frac)*DIG_PER_DEC1, prec2=from2->intg+frac2, - error, i, intg0, frac0, len1, len2, dlen1, dintg, div=(!mod); + error, i, intg0, frac0, len1, len2, dintg, div=(!mod); dec1 *buf0, *buf1=from1->buf, *buf2=from2->buf, *tmp1, - *start2, *stop2, *stop1, *stop0, norm2, carry, *start1; + *start2, *stop2, *stop1, *stop0, norm2, carry, *start1, dcarry; dec2 norm_factor, x, guess, y; LINT_INIT(error); @@ -2043,7 +2043,7 @@ static int do_div_mod(decimal_t *from1, decimal_t *from2, /* removing end zeroes */ while (*stop2 == 0 && stop2 >= start2) stop2--; - len2= ++stop2 - start2; + len2= stop2++ - start2; /* calculating norm2 (normalized *start2) - we need *start2 to be large @@ -2055,87 +2055,70 @@ static int do_div_mod(decimal_t *from1, decimal_t *from2, */ norm_factor=DIG_BASE/(*start2+1); norm2=(dec1)(norm_factor*start2[0]); - if (likely(len2>1)) + if (likely(len2>0)) norm2+=(dec1)(norm_factor*start2[1]/DIG_BASE); + if (*start1 < *start2) + dcarry=*start1++; + else + dcarry=0; + /* main loop */ - for ( ; buf0 < stop0; buf0++) + for (; buf0 < stop0; buf0++) { /* short-circuit, if possible */ - if (unlikely(*start1 == 0)) - { - start1++; - if (likely(div)) - *buf0=0; - continue; - } - - /* D3: make a guess */ - if (*start1 >= *start2) - { - x=start1[0]; - y=start1[1]; - dlen1=len2-1; - } + if (unlikely(dcarry == 0 && *start1 < *start2)) + guess=0; else { - x=((dec2)start1[0])*DIG_BASE+start1[1]; - y=start1[2]; - dlen1=len2; - } - guess=(norm_factor*x+norm_factor*y/DIG_BASE)/norm2; - if (unlikely(guess >= DIG_BASE)) - guess=DIG_BASE-1; - if (likely(len2>1)) - { - /* hmm, this is a suspicious trick - I removed normalization here */ - if (start2[1]*guess > (x-guess*start2[0])*DIG_BASE+y) - guess--; - if (unlikely(start2[1]*guess > (x-guess*start2[0])*DIG_BASE+y)) - guess--; - DBUG_ASSERT(start2[1]*guess <= (x-guess*start2[0])*DIG_BASE+y); - } + /* D3: make a guess */ + x=start1[0]+((dec2)dcarry)*DIG_BASE; + y=start1[1]; + guess=(norm_factor*x+norm_factor*y/DIG_BASE)/norm2; + if (unlikely(guess >= DIG_BASE)) + guess=DIG_BASE-1; + if (likely(len2>0)) + { + /* hmm, this is a suspicious trick - I removed normalization here */ + if (start2[1]*guess > (x-guess*start2[0])*DIG_BASE+y) + guess--; + if (unlikely(start2[1]*guess > (x-guess*start2[0])*DIG_BASE+y)) + guess--; + DBUG_ASSERT(start2[1]*guess <= (x-guess*start2[0])*DIG_BASE+y); + } - /* D4: multiply and subtract */ - buf2=stop2; - buf1=start1+dlen1; - DBUG_ASSERT(buf1 < stop1); - for (carry=0; buf2 > start2; buf1--) - { - dec1 hi, lo; - x=guess * (*--buf2); - hi=(dec1)(x/DIG_BASE); - lo=(dec1)(x-((dec2)hi)*DIG_BASE); - SUB2(*buf1, *buf1, lo, carry); - carry+=hi; - } - for (; buf1 >= start1; buf1--) - { - SUB2(*buf1, *buf1, 0, carry); - } - - /* D5: check the remainder */ - if (unlikely(carry)) - { - DBUG_ASSERT(carry==1); - /* D6: correct the guess */ - guess--; + /* D4: multiply and subtract */ buf2=stop2; - buf1=start1+dlen1; + buf1=start1+len2; + DBUG_ASSERT(buf1 < stop1); for (carry=0; buf2 > start2; buf1--) { - ADD(*buf1, *buf1, *--buf2, carry); + dec1 hi, lo; + x=guess * (*--buf2); + hi=(dec1)(x/DIG_BASE); + lo=(dec1)(x-((dec2)hi)*DIG_BASE); + SUB2(*buf1, *buf1, lo, carry); + carry+=hi; } - for (; buf1 >= start1; buf1--) + carry= dcarry < carry; + + /* D5: check the remainder */ + if (unlikely(carry)) { - SUB2(*buf1, *buf1, 0, carry); + /* D6: correct the guess */ + guess--; + buf2=stop2; + buf1=start1+len2; + for (carry=0; buf2 > start2; buf1--) + { + ADD(*buf1, *buf1, *--buf2, carry); + } } - DBUG_ASSERT(carry==1); } if (likely(div)) *buf0=(dec1)guess; - if (*start1 == 0) - start1++; + dcarry= *start1; + start1++; } if (mod) { @@ -2144,6 +2127,8 @@ static int do_div_mod(decimal_t *from1, decimal_t *from2, intg=prec1-frac1 frac=max(frac1, frac2)=to->frac */ + if (dcarry) + *--start1=dcarry; buf0=to->buf; intg0=ROUND_UP(prec1-frac1)-(start1-tmp1); frac0=ROUND_UP(to->frac); @@ -2753,6 +2738,8 @@ int main() test_dv("1.000000000000", "3","0.333333333333333333", 0); test_dv("1", "1","1.000000000", 0); test_dv("0.0123456789012345678912345", "9999999999","0.000000000001234567890246913578148141", 0); + test_dv("10.333000000", "12.34500","0.837019036046982584042122316", 0); + test_dv("10.000000000060", "2","5.000000000030000000", 0); printf("==== decimal_mod ====\n"); test_md("234","10","4", 0);