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@ -1,10 +1,20 @@ |
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#include "scan.h" |
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size_t scan_8short(const char* src,unsigned short* dest) { |
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/* make a copy of src so we can return the number of bytes we progressed */ |
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register const char *tmp=src; |
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/* this is called l because we copy and pasted from 8long, where l
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* stood for "long" */ |
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register unsigned short l=0; |
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register unsigned char c; |
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/* *tmp - '0' can be negative, but casting to unsigned char makes
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* those cases positive and large; that means we only need one |
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* comparison. This trick is no longer needed on modern compilers, |
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* but we also want to produce good code on old compilers :) */ |
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while ((c=(unsigned char)(*tmp-'0'))<8) { |
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/* overflow check; for each digit we multiply by 8 and then add the
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* digit; 0-7 needs 3 bits of storage, so we need to check if the |
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* uppermost 3 bits of l are empty. Do it by shifting to the right */ |
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if (l>>(sizeof(l)*8-3)) break; |
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l=(unsigned short)(l*8+c); |
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++tmp; |
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