Hi,
looking at ooRexx's implemetation of x2c I find the original code much
easier to understand and to reason about. Instead of hand-tuning an
implementation I'd like to know why the native implementation is slower
than your approach. I'd suspect it's because it's using strchr to validate
each character against a set of valid characters. Might want to improve
that instead...
It might be good to use VTune to do the actual performance analysis because
that will give a cycle-accurate break-down of instructions.
Cheers,
Moritz
On Fri, Apr 19, 2019 at 4:18 PM Rony G. Flatscher <rony.flatsc...@wu.ac.at>
wrote:
> Double-checked the test hex strings and their positions of illegal
> whitespace chars, here the native routine with the corrected position:
>
> int64_t hex2char(RexxCallContext *rcc, CSTRING hexData, size_t len, char
> *data)
> {
> // check for trailing whitespace
> char tmp=(hexData[len-1]); // get last character (must not be
> whitespace)
> if (tmp==' ' || tmp=='\t')
> rcc->ThrowException1(93931, rcc->UnsignedInt64ToObject(len));
>
> size_t dIdx=0;
>
> for (size_t i=0; i<len; i++)
> {
>
> if (hexData[i]>='0' && hexData[i]<='9') tmp=hexData[i]-'0';
> else if (hexData[i]>='A' && hexData[i]<='F') tmp=hexData[i]-'A'+10;
> else if (hexData[i]>='a' && hexData[i]<='f') tmp=hexData[i]-'a'+10;
> else
> {
> // check for leading whitespace
> if (dIdx==0 && (hexData[i]==' ' || hexData[i]=='\t') )
> rcc->ThrowException1(93931, rcc->Int32ToObject(1));
>
> if (hexData[i]==' ' || hexData[i]=='\t') continue; // skip on
> whitespace
>
> // illegal hex digit
> char buf[64];
> snprintf(buf, 64, "%c\0", hexData[i]);
> rcc->ThrowException1(93933, rcc->NewStringFromAsciiz(buf));
> }
> tmp<<=4; // shift to high order nibble
> i++; // position on next hex digit
>
> if (i==len) // we are beyond the hex string and missing the second
> hex digit
> {
> char buf[256];
> snprintf(buf, 256, "Hexadecimal string incomplete: hexadecimal
> pair starting with the character \"%c\" in position %zd is missing the second
> hexadecimal digit\0", hexData[i-1], len);
> rcc->ThrowException1(93900,rcc->NewStringFromAsciiz(buf));
> }
>
>
> if (hexData[i]>='0' && hexData[i]<='9') tmp|=hexData[i]-'0';
> else if (hexData[i]>='A' && hexData[i]<='F') tmp|=hexData[i]-'A'+10;
> else if (hexData[i]>='a' && hexData[i]<='f') tmp|=hexData[i]-'a'+10;
> else if (hexData[i]==' ' || hexData[i]=='\t') // also whitespace not
> allowed in between of a hex pair
> rcc->ThrowException1(93931,
> rcc->UnsignedInt64ToObject(i*+1*));
> else // illegal hex digit
> {
> char buf[64];
> snprintf(buf, 64, "%c\0", hexData[i]);
> rcc->ThrowException1(93933, rcc->NewStringFromAsciiz(buf));
> }
> data[dIdx++]=tmp;
> }
> data[dIdx]='\0';
> return (int64_t)dIdx; // return number or characters in data
> }
>
>
> ---rony
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> Oorexx-devel@lists.sourceforge.net
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>
--
Moritz Hoffmann;
http://antiguru.de/
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