71 lines
1.9 KiB
ArmAsm
71 lines
1.9 KiB
ArmAsm
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/*
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* arch/alpha/lib/strchr.S
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* Contributed by Richard Henderson (rth@tamu.edu)
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*
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* Return the address of a given character within a null-terminated
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* string, or null if it is not found.
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*/
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#include <asm/regdef.h>
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.set noreorder
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.set noat
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.align 3
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.globl strchr
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.ent strchr
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strchr:
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.frame sp, 0, ra
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.prologue 0
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zapnot a1, 1, a1 # e0 : zero extend the search character
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ldq_u t0, 0(a0) # .. e1 : load first quadword
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sll a1, 8, t5 # e0 : replicate the search character
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andnot a0, 7, v0 # .. e1 : align our loop pointer
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or t5, a1, a1 # e0 :
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lda t4, -1 # .. e1 : build garbage mask
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sll a1, 16, t5 # e0 :
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cmpbge zero, t0, t2 # .. e1 : bits set iff byte == zero
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mskqh t4, a0, t4 # e0 :
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or t5, a1, a1 # .. e1 :
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sll a1, 32, t5 # e0 :
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cmpbge zero, t4, t4 # .. e1 : bits set iff byte is garbage
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or t5, a1, a1 # e0 :
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xor t0, a1, t1 # .. e1 : make bytes == c zero
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cmpbge zero, t1, t3 # e0 : bits set iff byte == c
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or t2, t3, t0 # e1 : bits set iff char match or zero match
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andnot t0, t4, t0 # e0 : clear garbage bits
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bne t0, $found # .. e1 (zdb)
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$loop: ldq t0, 8(v0) # e0 :
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addq v0, 8, v0 # .. e1 :
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nop # e0 :
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xor t0, a1, t1 # .. e1 (ev5 data stall)
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cmpbge zero, t0, t2 # e0 : bits set iff byte == 0
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cmpbge zero, t1, t3 # .. e1 : bits set iff byte == c
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or t2, t3, t0 # e0 :
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beq t0, $loop # .. e1 (zdb)
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$found: negq t0, t1 # e0 : clear all but least set bit
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and t0, t1, t0 # e1 (stall)
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and t0, t3, t1 # e0 : bit set iff byte was the char
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beq t1, $retnull # .. e1 (zdb)
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and t0, 0xf0, t2 # e0 : binary search for that set bit
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and t0, 0xcc, t3 # .. e1 :
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and t0, 0xaa, t4 # e0 :
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cmovne t2, 4, t2 # .. e1 :
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cmovne t3, 2, t3 # e0 :
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cmovne t4, 1, t4 # .. e1 :
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addq t2, t3, t2 # e0 :
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addq v0, t4, v0 # .. e1 :
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addq v0, t2, v0 # e0 :
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ret # .. e1 :
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$retnull:
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mov zero, v0 # e0 :
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ret # .. e1 :
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.end strchr
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