/* Optimized version of the standard memcmp() function. This file is part of the GNU C Library. Copyright (C) 2000, 2001, 2004 Free Software Foundation, Inc. Contributed by Dan Pop <Dan.Pop@cern.ch>. The GNU C Library is free software; you can redistribute it and/or modify it under the terms of the GNU Lesser General Public License as published by the Free Software Foundation; either version 2.1 of the License, or (at your option) any later version. The GNU C Library is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public License for more details. You should have received a copy of the GNU Lesser General Public License along with the GNU C Library; if not, see <http://www.gnu.org/licenses/>. */ /* Return: the result of the comparison Inputs: in0: dest (aka s1) in1: src (aka s2) in2: byte count In this form, it assumes little endian mode. For big endian mode, the the two shifts in .l2 must be inverted: shl tmp1[0] = r[1 + MEMLAT], sh1 // tmp1 = w0 << sh1 shr.u tmp2[0] = r[0 + MEMLAT], sh2 // tmp2 = w1 >> sh2 and all the mux1 instructions should be replaced by plain mov's. */ #include <sysdep.h> #undef ret #define OP_T_THRES 16 #define OPSIZ 8 #define MEMLAT 2 #define start r15 #define saved_pr r17 #define saved_lc r18 #define dest r19 #define src r20 #define len r21 #define asrc r22 #define tmp r23 #define value1 r24 #define value2 r25 #define sh2 r28 #define sh1 r29 #define loopcnt r30 ENTRY(memcmp) .prologue alloc r2 = ar.pfs, 3, 37, 0, 40 .rotr r[MEMLAT + 2], q[MEMLAT + 5], tmp1[4], tmp2[4], val[2] .rotp p[MEMLAT + 4 + 1] mov ret0 = r0 /* by default return value = 0 */ .save pr, saved_pr mov saved_pr = pr /* save the predicate registers */ .save ar.lc, saved_lc mov saved_lc = ar.lc /* save the loop counter */ .body mov dest = in0 /* dest */ mov src = in1 /* src */ mov len = in2 /* len */ sub tmp = r0, in0 /* tmp = -dest */ ;; and loopcnt = 7, tmp /* loopcnt = -dest % 8 */ cmp.ge p6, p0 = OP_T_THRES, len /* is len <= OP_T_THRES */ (p6) br.cond.spnt .cmpfew /* compare byte by byte */ ;; cmp.eq p6, p0 = loopcnt, r0 (p6) br.cond.sptk .dest_aligned sub len = len, loopcnt /* len -= -dest % 8 */ adds loopcnt = -1, loopcnt /* --loopcnt */ ;; mov ar.lc = loopcnt .l1: /* copy -dest % 8 bytes */ ld1 value1 = [src], 1 /* value = *src++ */ ld1 value2 = [dest], 1 ;; cmp.ne p6, p0 = value1, value2 (p6) br.cond.spnt .done br.cloop.dptk .l1 .dest_aligned: and sh1 = 7, src /* sh1 = src % 8 */ and tmp = -8, len /* tmp = len & -OPSIZ */ and asrc = -8, src /* asrc = src & -OPSIZ -- align src */ shr.u loopcnt = len, 3 /* loopcnt = len / 8 */ and len = 7, len ;; /* len = len % 8 */ shl sh1 = sh1, 3 /* sh1 = 8 * (src % 8) */ adds loopcnt = -1, loopcnt /* --loopcnt */ mov pr.rot = 1 << 16 ;; /* set rotating predicates */ sub sh2 = 64, sh1 /* sh2 = 64 - sh1 */ mov ar.lc = loopcnt /* set LC */ cmp.eq p6, p0 = sh1, r0 /* is the src aligned? */ (p6) br.cond.sptk .src_aligned add src = src, tmp /* src += len & -OPSIZ */ mov ar.ec = MEMLAT + 4 + 1 /* four more passes needed */ ld8 r[1] = [asrc], 8 ;; /* r[1] = w0 */ .align 32 /* We enter this loop with p6 cleared by the above comparison */ .l2: (p[0]) ld8 r[0] = [asrc], 8 /* r[0] = w1 */ (p[0]) ld8 q[0] = [dest], 8 (p[MEMLAT]) shr.u tmp1[0] = r[1 + MEMLAT], sh1 /* tmp1 = w0 >> sh1 */ (p[MEMLAT]) shl tmp2[0] = r[0 + MEMLAT], sh2 /* tmp2 = w1 << sh2 */ (p[MEMLAT+4]) cmp.ne p6, p0 = q[MEMLAT + 4], val[1] (p[MEMLAT+3]) or val[0] = tmp1[3], tmp2[3] /* val = tmp1 | tmp2 */ (p6) br.cond.spnt .l2exit br.ctop.sptk .l2 br.cond.sptk .cmpfew .l3exit: mux1 value1 = r[MEMLAT], @rev mux1 value2 = q[MEMLAT], @rev cmp.ne p6, p0 = r0, r0 ;; /* clear p6 */ .l2exit: (p6) mux1 value1 = val[1], @rev (p6) mux1 value2 = q[MEMLAT + 4], @rev ;; cmp.ltu p6, p7 = value2, value1 ;; (p6) mov ret0 = -1 (p7) mov ret0 = 1 mov pr = saved_pr, -1 /* restore the predicate registers */ mov ar.lc = saved_lc /* restore the loop counter */ br.ret.sptk.many b0 .src_aligned: cmp.ne p6, p0 = r0, r0 /* clear p6 */ mov ar.ec = MEMLAT + 1 ;; /* set EC */ .l3: (p[0]) ld8 r[0] = [src], 8 (p[0]) ld8 q[0] = [dest], 8 (p[MEMLAT]) cmp.ne p6, p0 = r[MEMLAT], q[MEMLAT] (p6) br.cond.spnt .l3exit br.ctop.dptk .l3 ;; .cmpfew: cmp.eq p6, p0 = len, r0 /* is len == 0 ? */ adds len = -1, len /* --len; */ (p6) br.cond.spnt .restore_and_exit ;; mov ar.lc = len .l4: ld1 value1 = [src], 1 ld1 value2 = [dest], 1 ;; cmp.ne p6, p0 = value1, value2 (p6) br.cond.spnt .done br.cloop.dptk .l4 ;; .done: (p6) sub ret0 = value2, value1 /* don't execute it if falling thru */ .restore_and_exit: mov pr = saved_pr, -1 /* restore the predicate registers */ mov ar.lc = saved_lc /* restore the loop counter */ br.ret.sptk.many b0 END(memcmp) libc_hidden_def (memcmp) #ifdef __UCLIBC_SUSV3_LEGACY__ strong_alias (memcmp, bcmp) #endif