From d2a9940acbe6a74cc83e371baf2ef7c580e308bc Mon Sep 17 00:00:00 2001 From: Mark Dickinson Date: Wed, 13 Jan 2010 22:20:10 +0000 Subject: [PATCH] More dtoa.c cleanup; remove the need for bc.dplen, bc.dp0 and bc.dp1. --- Python/dtoa.c | 120 ++++++++++++++++++++------------------------------ 1 file changed, 47 insertions(+), 73 deletions(-) diff --git a/Python/dtoa.c b/Python/dtoa.c index c8985bc980c..8389eb2352a 100644 --- a/Python/dtoa.c +++ b/Python/dtoa.c @@ -270,7 +270,7 @@ typedef union { double d; ULong L[2]; } U; typedef struct BCinfo BCinfo; struct BCinfo { - int dp0, dp1, dplen, dsign, e0, nd, nd0, scale; + int dsign, e0, nd, nd0, scale; }; #define FFFFFFFF 0xffffffffUL @@ -437,7 +437,7 @@ multadd(Bigint *b, int m, int a) /* multiply by m and add a */ NULL on failure. */ static Bigint * -s2b(const char *s, int nd0, int nd, ULong y9, int dplen) +s2b(const char *s, int nd0, int nd, ULong y9) { Bigint *b; int i, k; @@ -451,18 +451,16 @@ s2b(const char *s, int nd0, int nd, ULong y9, int dplen) b->x[0] = y9; b->wds = 1; - i = 9; - if (9 < nd0) { - s += 9; - do { - b = multadd(b, 10, *s++ - '0'); - if (b == NULL) - return NULL; - } while(++i < nd0); - s += dplen; + if (nd <= 9) + return b; + + s += 9; + for (i = 9; i < nd0; i++) { + b = multadd(b, 10, *s++ - '0'); + if (b == NULL) + return NULL; } - else - s += dplen + 9; + s++; for(; i < nd; i++) { b = multadd(b, 10, *s++ - '0'); if (b == NULL) @@ -1180,26 +1178,14 @@ sulp(U *x, BCinfo *bc) bc is a struct containing information gathered during the parsing and estimation steps of _Py_dg_strtod. Description of fields follows: - bc->dp0 gives the position of the decimal point in the input string - (if any), relative to the start of s0. If there's no decimal - point, it points to one past the last significant digit. - - bc->dp1 gives the position immediately following the decimal point in - the input string, relative to the start of s0. If there's no - decimal point, it points to one past the last significant digit. - - bc->dplen gives the length of the decimal separator. In the current - implementation, which only allows '.' as a decimal separator, it's - 1 if a separator is present in the significant digits of s0, and 0 - otherwise. - bc->dsign is 1 if rv < decimal value, 0 if rv >= decimal value. In normal use, it should almost always be 1 when bigcomp is entered. bc->e0 gives the exponent of the input value, such that dv = (integer given by the bd->nd digits of s0) * 10**e0 - bc->nd gives the total number of significant digits of s0. + bc->nd gives the total number of significant digits of s0. It will + be at least 1. bc->nd0 gives the number of significant digits of s0 before the decimal separator. If there's no decimal separator, bc->nd0 == @@ -1218,13 +1204,14 @@ static int bigcomp(U *rv, const char *s0, BCinfo *bc) { Bigint *b, *d; - int b2, bbits, d2, dd, dig, i, j, nd, nd0, p2, p5; + int b2, bbits, d2, dd, i, nd, nd0, p2, p5; + dd = 0; /* silence compiler warning about possibly unused variable */ nd = bc->nd; nd0 = bc->nd0; p5 = nd + bc->e0; - if (rv->d == 0.) { /* special case: value near underflow-to-zero */ - /* threshold was rounded to zero */ + if (rv->d == 0.) { + /* special case because d2b doesn't handle 0.0 */ b = i2b(0); if (b == NULL) return -1; @@ -1243,9 +1230,8 @@ bigcomp(U *rv, const char *s0, BCinfo *bc) that b << i has at most P significant bits and p2 - i >= Emin - P + 1. */ i = P - bbits; - j = p2 - (Emin - P + 1); - if (i > j) - i = j; + if (i > p2 - (Emin - P + 1)) + i = p2 - (Emin - P + 1); /* increment i so that we shift b by an extra bit; then or-ing a 1 into the lsb of b gives us rv/2^(bc->scale) + 0.5ulp. */ b = lshift(b, ++i); @@ -1300,55 +1286,43 @@ bigcomp(U *rv, const char *s0, BCinfo *bc) } } - /* Now 10*b/d = exactly half-way between the two floating-point values - on either side of the input string. If b >= d, round down. */ + /* if b >= d, round down */ if (cmp(b, d) >= 0) { dd = -1; goto ret; } - /* Compute first digit of 10*b/d. */ - b = multadd(b, 10, 0); - if (b == NULL) { - Bfree(d); - return -1; - } - dig = quorem(b, d); - assert(dig < 10); - /* Compare b/d with s0 */ - - assert(nd > 0); - dd = 9999; /* silence gcc compiler warning */ - for(i = 0; i < nd0; ) { - if ((dd = s0[i++] - '0' - dig)) + for(i = 0; i < nd0; i++) { + b = multadd(b, 10, 0); + if (b == NULL) { + Bfree(d); + return -1; + } + dd = *s0++ - '0' - quorem(b, d); + if (dd) goto ret; if (!b->x[0] && b->wds == 1) { if (i < nd) dd = 1; goto ret; } - b = multadd(b, 10, 0); - if (b == NULL) { - Bfree(d); - return -1; - } - dig = quorem(b,d); } - for(j = bc->dp1; i++ < nd;) { - if ((dd = s0[j++] - '0' - dig)) + s0++; + for(; i < nd; i++) { + b = multadd(b, 10, 0); + if (b == NULL) { + Bfree(d); + return -1; + } + dd = *s0++ - '0' - quorem(b, d); + if (dd) goto ret; if (!b->x[0] && b->wds == 1) { if (i < nd) dd = 1; goto ret; } - b = multadd(b, 10, 0); - if (b == NULL) { - Bfree(d); - return -1; - } - dig = quorem(b,d); } if (b->x[0] || b->wds > 1) dd = -1; @@ -1369,7 +1343,7 @@ bigcomp(U *rv, const char *s0, BCinfo *bc) double _Py_dg_strtod(const char *s00, char **se) { - int bb2, bb5, bbe, bd2, bd5, bbbits, bs2, c, e, e1, error; + int bb2, bb5, bbe, bd2, bd5, bbbits, bs2, c, dp0, dp1, dplen, e, e1, error; int esign, i, j, k, nd, nd0, nf, nz, nz0, sign; const char *s, *s0, *s1; double aadj, aadj1; @@ -1378,7 +1352,7 @@ _Py_dg_strtod(const char *s00, char **se) BCinfo bc; Bigint *bb, *bb1, *bd, *bd0, *bs, *delta; - sign = nz0 = nz = bc.dplen = 0; + sign = nz0 = nz = dplen = 0; dval(&rv) = 0.; for(s = s00;;s++) switch(*s) { case '-': @@ -1417,11 +1391,11 @@ _Py_dg_strtod(const char *s00, char **se) else if (nd < 16) z = 10*z + c - '0'; nd0 = nd; - bc.dp0 = bc.dp1 = s - s0; + dp0 = dp1 = s - s0; if (c == '.') { c = *++s; - bc.dp1 = s - s0; - bc.dplen = bc.dp1 - bc.dp0; + dp1 = s - s0; + dplen = 1; if (!nd) { for(; c == '0'; c = *++s) nz++; @@ -1624,10 +1598,10 @@ _Py_dg_strtod(const char *s00, char **se) /* in IEEE arithmetic. */ i = j = 18; if (i > nd0) - j += bc.dplen; + j += dplen; for(;;) { - if (--j <= bc.dp1 && j >= bc.dp0) - j = bc.dp0 - 1; + if (--j <= dp1 && j >= dp0) + j = dp0 - 1; if (s0[j] != '0') break; --i; @@ -1640,11 +1614,11 @@ _Py_dg_strtod(const char *s00, char **se) y = 0; for(i = 0; i < nd0; ++i) y = 10*y + s0[i] - '0'; - for(j = bc.dp1; i < nd; ++i) + for(j = dp1; i < nd; ++i) y = 10*y + s0[j++] - '0'; } } - bd0 = s2b(s0, nd0, nd, y, bc.dplen); + bd0 = s2b(s0, nd0, nd, y); if (bd0 == NULL) goto failed_malloc;