11da177e4SLinus Torvalds/* 21da177e4SLinus Torvalds * arch/alpha/lib/ev67-strlen.S 31da177e4SLinus Torvalds * 21264 version by Rick Gorton <rick.gorton@alpha-processor.com> 41da177e4SLinus Torvalds * 51da177e4SLinus Torvalds * Finds length of a 0-terminated string. Optimized for the 61da177e4SLinus Torvalds * Alpha architecture: 71da177e4SLinus Torvalds * 81da177e4SLinus Torvalds * - memory accessed as aligned quadwords only 91da177e4SLinus Torvalds * - uses bcmpge to compare 8 bytes in parallel 101da177e4SLinus Torvalds * 111da177e4SLinus Torvalds * Much of the information about 21264 scheduling/coding comes from: 121da177e4SLinus Torvalds * Compiler Writer's Guide for the Alpha 21264 131da177e4SLinus Torvalds * abbreviated as 'CWG' in other comments here 141da177e4SLinus Torvalds * ftp.digital.com/pub/Digital/info/semiconductor/literature/dsc-library.html 151da177e4SLinus Torvalds * Scheduling notation: 161da177e4SLinus Torvalds * E - either cluster 171da177e4SLinus Torvalds * U - upper subcluster; U0 - subcluster U0; U1 - subcluster U1 181da177e4SLinus Torvalds * L - lower subcluster; L0 - subcluster L0; L1 - subcluster L1 191da177e4SLinus Torvalds */ 2000fc0e0dSAl Viro#include <asm/export.h> 211da177e4SLinus Torvalds .set noreorder 221da177e4SLinus Torvalds .set noat 231da177e4SLinus Torvalds 241da177e4SLinus Torvalds .globl strlen 251da177e4SLinus Torvalds .ent strlen 261da177e4SLinus Torvalds .align 4 271da177e4SLinus Torvaldsstrlen: 281da177e4SLinus Torvalds ldq_u $1, 0($16) # L : load first quadword ($16 may be misaligned) 291da177e4SLinus Torvalds lda $2, -1($31) # E : 301da177e4SLinus Torvalds insqh $2, $16, $2 # U : 311da177e4SLinus Torvalds andnot $16, 7, $0 # E : 321da177e4SLinus Torvalds 331da177e4SLinus Torvalds or $2, $1, $1 # E : 341da177e4SLinus Torvalds cmpbge $31, $1, $2 # E : $2 <- bitmask: bit i == 1 <==> i-th byte == 0 351da177e4SLinus Torvalds nop # E : 361da177e4SLinus Torvalds bne $2, $found # U : 371da177e4SLinus Torvalds 381da177e4SLinus Torvalds$loop: ldq $1, 8($0) # L : 391da177e4SLinus Torvalds addq $0, 8, $0 # E : addr += 8 401da177e4SLinus Torvalds cmpbge $31, $1, $2 # E : 411da177e4SLinus Torvalds beq $2, $loop # U : 421da177e4SLinus Torvalds 431da177e4SLinus Torvalds$found: 441da177e4SLinus Torvalds cttz $2, $3 # U0 : 451da177e4SLinus Torvalds addq $0, $3, $0 # E : 461da177e4SLinus Torvalds subq $0, $16, $0 # E : 471da177e4SLinus Torvalds ret $31, ($26) # L0 : 481da177e4SLinus Torvalds 491da177e4SLinus Torvalds .end strlen 5000fc0e0dSAl Viro EXPORT_SYMBOL(strlen) 51