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Postings from December 2000
Nicholas Clark <nick@ccl4.org> writes: >> So was I - looks_like_number is doing most of the work already, having it >> tally up the digits into an UV as it goes makes a lot of sense to me. >I'll be even happier if the arm backend optimiser likes the idea of *10 >being > >total ||= total << 2; >total = new_digit + total << 1; > >as that's 2 machine instructions, 2 clock cycles, whereas *10 is at least >4 IIRC. gcc will probably do that for you. I had to beat it over the head with a mallet to stop it doing shift+add that on DSPs where * is one cycle. > >> It is less clear that we want the hassle of the NV case. > >I wasn't thinking of the NV case. Fine - carry on. >I was thinking something like > >int son_looks_like_number (SV * sv, UV *value); >that returns flags about what it found out in the int, and the value in >*value if the pointer is non null, and the value doesn't overflow. >(flags include "minus", "erk we've overflowed the UV", "saw a decimal point" >"saw e notation" and "infinity" as now; the UV would return the abs value) Apart from the name that is okay. I would be tempted to make it return the bit-pattern rather than the abs value - but I assume you have your reasons. -- Nick Ing-Simmons <nik@tiuk.ti.com> Via, but not speaking for: Texas Instruments Ltd.Thread Previous | Thread Next