162306a36Sopenharmony_ci/* SPDX-License-Identifier: GPL-2.0 */ 262306a36Sopenharmony_ci/* 362306a36Sopenharmony_ci * arch/alpha/lib/ev67-strlen.S 462306a36Sopenharmony_ci * 21264 version by Rick Gorton <rick.gorton@alpha-processor.com> 562306a36Sopenharmony_ci * 662306a36Sopenharmony_ci * Finds length of a 0-terminated string. Optimized for the 762306a36Sopenharmony_ci * Alpha architecture: 862306a36Sopenharmony_ci * 962306a36Sopenharmony_ci * - memory accessed as aligned quadwords only 1062306a36Sopenharmony_ci * - uses bcmpge to compare 8 bytes in parallel 1162306a36Sopenharmony_ci * 1262306a36Sopenharmony_ci * Much of the information about 21264 scheduling/coding comes from: 1362306a36Sopenharmony_ci * Compiler Writer's Guide for the Alpha 21264 1462306a36Sopenharmony_ci * abbreviated as 'CWG' in other comments here 1562306a36Sopenharmony_ci * ftp.digital.com/pub/Digital/info/semiconductor/literature/dsc-library.html 1662306a36Sopenharmony_ci * Scheduling notation: 1762306a36Sopenharmony_ci * E - either cluster 1862306a36Sopenharmony_ci * U - upper subcluster; U0 - subcluster U0; U1 - subcluster U1 1962306a36Sopenharmony_ci * L - lower subcluster; L0 - subcluster L0; L1 - subcluster L1 2062306a36Sopenharmony_ci */ 2162306a36Sopenharmony_ci#include <linux/export.h> 2262306a36Sopenharmony_ci .set noreorder 2362306a36Sopenharmony_ci .set noat 2462306a36Sopenharmony_ci 2562306a36Sopenharmony_ci .globl strlen 2662306a36Sopenharmony_ci .ent strlen 2762306a36Sopenharmony_ci .align 4 2862306a36Sopenharmony_cistrlen: 2962306a36Sopenharmony_ci ldq_u $1, 0($16) # L : load first quadword ($16 may be misaligned) 3062306a36Sopenharmony_ci lda $2, -1($31) # E : 3162306a36Sopenharmony_ci insqh $2, $16, $2 # U : 3262306a36Sopenharmony_ci andnot $16, 7, $0 # E : 3362306a36Sopenharmony_ci 3462306a36Sopenharmony_ci or $2, $1, $1 # E : 3562306a36Sopenharmony_ci cmpbge $31, $1, $2 # E : $2 <- bitmask: bit i == 1 <==> i-th byte == 0 3662306a36Sopenharmony_ci nop # E : 3762306a36Sopenharmony_ci bne $2, $found # U : 3862306a36Sopenharmony_ci 3962306a36Sopenharmony_ci$loop: ldq $1, 8($0) # L : 4062306a36Sopenharmony_ci addq $0, 8, $0 # E : addr += 8 4162306a36Sopenharmony_ci cmpbge $31, $1, $2 # E : 4262306a36Sopenharmony_ci beq $2, $loop # U : 4362306a36Sopenharmony_ci 4462306a36Sopenharmony_ci$found: 4562306a36Sopenharmony_ci cttz $2, $3 # U0 : 4662306a36Sopenharmony_ci addq $0, $3, $0 # E : 4762306a36Sopenharmony_ci subq $0, $16, $0 # E : 4862306a36Sopenharmony_ci ret $31, ($26) # L0 : 4962306a36Sopenharmony_ci 5062306a36Sopenharmony_ci .end strlen 5162306a36Sopenharmony_ci EXPORT_SYMBOL(strlen) 52