diff options
Diffstat (limited to 'erts/emulator/beam/big.c')
| -rw-r--r-- | erts/emulator/beam/big.c | 153 |
1 files changed, 153 insertions, 0 deletions
diff --git a/erts/emulator/beam/big.c b/erts/emulator/beam/big.c index 02d37e24df..29e677d2e5 100644 --- a/erts/emulator/beam/big.c +++ b/erts/emulator/beam/big.c @@ -2732,3 +2732,156 @@ bytebuf_to_integer_1_done: return res; } + +int do_list_to_integer(Process *p, Eterm orig_list, + Eterm *integer, Eterm *rest) +{ + Sint i = 0; + Uint ui = 0; + int skip = 0; + int neg = 0; + Sint n = 0; + int m; + int lg2; + Eterm res; + Eterm* hp; + Eterm *hp_end; + Eterm lst = orig_list; + Eterm tail = lst; + int error_res = LTI_BAD_STRUCTURE; + + if (is_nil(lst)) { + error_res = LTI_NO_INTEGER; + error: + *rest = tail; + *integer = make_small(0); + return error_res; + } + if (is_not_list(lst)) + goto error; + + /* if first char is a '-' then it is a negative integer */ + if (CAR(list_val(lst)) == make_small('-')) { + neg = 1; + skip = 1; + lst = CDR(list_val(lst)); + if (is_not_list(lst)) { + tail = lst; + error_res = LTI_NO_INTEGER; + goto error; + } + } else if (CAR(list_val(lst)) == make_small('+')) { + /* ignore plus */ + skip = 1; + lst = CDR(list_val(lst)); + if (is_not_list(lst)) { + tail = lst; + error_res = LTI_NO_INTEGER; + goto error; + } + } + + /* Calculate size and do type check */ + + while(1) { + if (is_not_small(CAR(list_val(lst)))) { + break; + } + if (unsigned_val(CAR(list_val(lst))) < '0' || + unsigned_val(CAR(list_val(lst))) > '9') { + break; + } + ui = ui * 10; + ui = ui + unsigned_val(CAR(list_val(lst))) - '0'; + n++; + lst = CDR(list_val(lst)); + if (is_nil(lst)) { + break; + } + if (is_not_list(lst)) { + break; + } + } + + tail = lst; + if (!n) { + error_res = LTI_NO_INTEGER; + goto error; + } + + + /* If n <= 8 then we know it's a small int + ** since 2^27 = 134217728. If n > 8 then we must + ** construct a bignum and let that routine do the checking + */ + + if (n <= SMALL_DIGITS) { /* It must be small */ + if (neg) i = -(Sint)ui; + else i = (Sint)ui; + res = make_small(i); + } else { + /* Convert from log10 to log2 by multiplying with 1/log10(2)=3.3219 + which we round up to (3 + 1/3) */ + lg2 = (n+1)*3 + (n+1)/3 + 1; + m = (lg2+D_EXP-1)/D_EXP; /* number of digits */ + m = BIG_NEED_SIZE(m); /* number of words + thing */ + + hp = HAlloc(p, m); + hp_end = hp + m; + + lst = orig_list; + if (skip) + lst = CDR(list_val(lst)); + + /* load first digits (at least one digit) */ + if ((i = (n % D_DECIMAL_EXP)) == 0) + i = D_DECIMAL_EXP; + n -= i; + m = 0; + while(i--) { + m = 10*m + (unsigned_val(CAR(list_val(lst))) - '0'); + lst = CDR(list_val(lst)); + } + res = small_to_big(m, hp); /* load first digits */ + + while(n) { + i = D_DECIMAL_EXP; + n -= D_DECIMAL_EXP; + m = 0; + while(i--) { + m = 10*m + (unsigned_val(CAR(list_val(lst))) - '0'); + lst = CDR(list_val(lst)); + } + if (is_small(res)) + res = small_to_big(signed_val(res), hp); + res = big_times_small(res, D_DECIMAL_BASE, hp); + if (is_small(res)) + res = small_to_big(signed_val(res), hp); + res = big_plus_small(res, m, hp); + } + + if (neg) { + if (is_small(res)) + res = make_small(-signed_val(res)); + else { + Uint *big = big_val(res); /* point to thing */ + *big = bignum_header_neg(*big); + } + } + + if (is_not_small(res)) { + res = big_plus_small(res, 0, hp); /* includes conversion to small */ + + if (is_not_small(res)) { + hp += (big_arity(res)+1); + } + } + HRelease(p,hp_end,hp); + } + *integer = res; + *rest = tail; + if (tail != NIL) { + return LTI_SOME_INTEGER; + } + return LTI_ALL_INTEGER; +} |