diff options
author | Karl Williamson <khw@cpan.org> | 2021-07-18 17:30:49 -0600 |
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committer | Karl Williamson <khw@cpan.org> | 2021-08-06 08:48:16 -0600 |
commit | 6c4aa50c3d02831e0adee8be4d10577b03de815d (patch) | |
tree | 15ace2cd9c4ae67046ea3877aa3102b2dfc90584 /doop.c | |
parent | 35e4fe1f5a6c9fdcf227320cf569bcbd28da463a (diff) | |
download | perl-6c4aa50c3d02831e0adee8be4d10577b03de815d.tar.gz |
doop.c: Refactor do_vecget()
By using a switch statement this function can be cut in half, with fewer
conditionals executed.
Diffstat (limited to 'doop.c')
-rw-r--r-- | doop.c | 166 |
1 files changed, 50 insertions, 116 deletions
@@ -731,7 +731,7 @@ Perl_do_sprintf(pTHX_ SV *sv, SSize_t len, SV **sarg) UV Perl_do_vecget(pTHX_ SV *sv, STRLEN offset, int size) { - STRLEN srclen, len, avail, uoffset, bitoffs = 0; + STRLEN srclen, avail, uoffset; const I32 svpv_flags = ((PL_op->op_flags & OPf_MOD || LVRET) ? SV_UNDEF_RETURNS_NULL : 0); unsigned char *s = (unsigned char *) @@ -758,131 +758,65 @@ Perl_do_vecget(pTHX_ SV *sv, STRLEN offset, int size) } } - if (size < 8) { - bitoffs = ((offset % 8) * size) % 8; + if (size <= 8) { + STRLEN bitoffs = ((offset % 8) * size) % 8; uoffset = offset / (8 / size); - } - else if (size > 8) { - int n = size/8; - if (offset > Size_t_MAX / n - 1) /* would overflow */ - return 0; - uoffset = offset*n; - } - else - uoffset = offset; - - if (uoffset >= srclen) - return 0; - len = (bitoffs + size + 7)/8; /* required number of bytes */ - avail = srclen - uoffset; /* available number of bytes */ + if (uoffset >= srclen) + return 0; - /* Does the byte range overlap the end of the string? If so, - * handle specially. */ - if (avail < len) { - if (size <= 8) - retnum = 0; - else { - if (size == 16) { - assert(avail == 1); - retnum = (UV) s[uoffset] << 8; - } - else if (size == 32) { - assert(avail >= 1 && avail <= 3); - if (avail == 1) - retnum = - ((UV) s[uoffset ] << 24); - else if (avail == 2) - retnum = - ((UV) s[uoffset ] << 24) + - ((UV) s[uoffset + 1] << 16); - else - retnum = - ((UV) s[uoffset ] << 24) + - ((UV) s[uoffset + 1] << 16) + - ( s[uoffset + 2] << 8); - } -#ifdef UV_IS_QUAD - else if (size == 64) { - Perl_ck_warner(aTHX_ packWARN(WARN_PORTABLE), - "Bit vector size > 32 non-portable"); - assert(avail >= 1 && avail <= 7); - if (avail == 1) - retnum = - (UV) s[uoffset ] << 56; - else if (avail == 2) - retnum = - ((UV) s[uoffset ] << 56) + - ((UV) s[uoffset + 1] << 48); - else if (avail == 3) - retnum = - ((UV) s[uoffset ] << 56) + - ((UV) s[uoffset + 1] << 48) + - ((UV) s[uoffset + 2] << 40); - else if (avail == 4) - retnum = - ((UV) s[uoffset ] << 56) + - ((UV) s[uoffset + 1] << 48) + - ((UV) s[uoffset + 2] << 40) + - ((UV) s[uoffset + 3] << 32); - else if (avail == 5) - retnum = - ((UV) s[uoffset ] << 56) + - ((UV) s[uoffset + 1] << 48) + - ((UV) s[uoffset + 2] << 40) + - ((UV) s[uoffset + 3] << 32) + - ((UV) s[uoffset + 4] << 24); - else if (avail == 6) - retnum = - ((UV) s[uoffset ] << 56) + - ((UV) s[uoffset + 1] << 48) + - ((UV) s[uoffset + 2] << 40) + - ((UV) s[uoffset + 3] << 32) + - ((UV) s[uoffset + 4] << 24) + - ((UV) s[uoffset + 5] << 16); - else - retnum = - ((UV) s[uoffset ] << 56) + - ((UV) s[uoffset + 1] << 48) + - ((UV) s[uoffset + 2] << 40) + - ((UV) s[uoffset + 3] << 32) + - ((UV) s[uoffset + 4] << 24) + - ((UV) s[uoffset + 5] << 16) + - ((UV) s[uoffset + 6] << 8); - } -#endif - } - } - else if (size < 8) retnum = (s[uoffset] >> bitoffs) & nBIT_MASK(size); + } else { - if (size == 8) - retnum = s[uoffset]; - else if (size == 16) - retnum = - ((UV) s[uoffset] << 8) + - s[uoffset + 1]; - else if (size == 32) - retnum = - ((UV) s[uoffset ] << 24) + - ((UV) s[uoffset + 1] << 16) + - ( s[uoffset + 2] << 8) + - s[uoffset + 3]; + int n = size / 8; /* required number of bytes */ + #ifdef UV_IS_QUAD - else if (size == 64) { + + if (size == 64) { Perl_ck_warner(aTHX_ packWARN(WARN_PORTABLE), "Bit vector size > 32 non-portable"); - retnum = - ((UV) s[uoffset ] << 56) + - ((UV) s[uoffset + 1] << 48) + - ((UV) s[uoffset + 2] << 40) + - ((UV) s[uoffset + 3] << 32) + - ((UV) s[uoffset + 4] << 24) + - ((UV) s[uoffset + 5] << 16) + - ( s[uoffset + 6] << 8) + - s[uoffset + 7]; } #endif + if (offset > Size_t_MAX / n - 1) /* would overflow */ + return 0; + + uoffset = offset * n; + + if (uoffset >= srclen) + return 0; + + avail = srclen - uoffset; /* available number of bytes */ + + switch (MIN(n, avail)) { + +#ifdef UV_IS_QUAD + + case 8: + retnum += ((UV) s[uoffset + 7]); + /* FALLTHROUGH */ + case 7: + retnum += ((UV) s[uoffset + 6] << 8); /* = size - 56 */ + /* FALLTHROUGH */ + case 6: + retnum += ((UV) s[uoffset + 5] << 16); /* = size - 48 */ + /* FALLTHROUGH */ + case 5: + retnum += ((UV) s[uoffset + 4] << 24); /* = size - 40 */ +#endif + /* FALLTHROUGH */ + case 4: + retnum += ((UV) s[uoffset + 3] << (size - 32)); + /* FALLTHROUGH */ + case 3: + retnum += ((UV) s[uoffset + 2] << (size - 24)); + /* FALLTHROUGH */ + case 2: + retnum += ((UV) s[uoffset + 1] << (size - 16)); + /* FALLTHROUGH */ + case 1: + retnum += ((UV) s[uoffset ] << (size - 8)); + break; + } } return retnum; |