2008-05-19 16:53:02 -07:00
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/*
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2005-04-16 15:20:36 -07:00
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* memscan.S: Optimized memscan for the Sparc.
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*
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* Copyright (C) 1996 David S. Miller (davem@caip.rutgers.edu)
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*/
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/* In essence, this is just a fancy strlen. */
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#define LO_MAGIC 0x01010101
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#define HI_MAGIC 0x80808080
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.text
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.align 4
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.globl __memscan_zero, __memscan_generic
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.globl memscan
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__memscan_zero:
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/* %o0 = addr, %o1 = size */
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cmp %o1, 0
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bne,a 1f
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andcc %o0, 3, %g0
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retl
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nop
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1:
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be mzero_scan_word
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sethi %hi(HI_MAGIC), %g2
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ldsb [%o0], %g3
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mzero_still_not_word_aligned:
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cmp %g3, 0
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bne 1f
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add %o0, 1, %o0
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retl
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sub %o0, 1, %o0
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1:
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subcc %o1, 1, %o1
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bne,a 1f
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andcc %o0, 3, %g0
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retl
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nop
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1:
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bne,a mzero_still_not_word_aligned
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ldsb [%o0], %g3
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sethi %hi(HI_MAGIC), %g2
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mzero_scan_word:
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or %g2, %lo(HI_MAGIC), %o3
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sethi %hi(LO_MAGIC), %g3
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or %g3, %lo(LO_MAGIC), %o2
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mzero_next_word:
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ld [%o0], %g2
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mzero_next_word_preloaded:
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sub %g2, %o2, %g2
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mzero_next_word_preloaded_next:
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andcc %g2, %o3, %g0
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bne mzero_byte_zero
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add %o0, 4, %o0
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mzero_check_out_of_fuel:
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subcc %o1, 4, %o1
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bg,a 1f
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ld [%o0], %g2
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retl
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nop
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1:
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b mzero_next_word_preloaded_next
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sub %g2, %o2, %g2
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/* Check every byte. */
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mzero_byte_zero:
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ldsb [%o0 - 4], %g2
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cmp %g2, 0
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bne mzero_byte_one
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sub %o0, 4, %g3
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retl
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mov %g3, %o0
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mzero_byte_one:
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ldsb [%o0 - 3], %g2
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cmp %g2, 0
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bne,a mzero_byte_two_and_three
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ldsb [%o0 - 2], %g2
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retl
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sub %o0, 3, %o0
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mzero_byte_two_and_three:
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cmp %g2, 0
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bne,a 1f
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ldsb [%o0 - 1], %g2
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retl
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sub %o0, 2, %o0
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1:
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cmp %g2, 0
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bne,a mzero_next_word_preloaded
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ld [%o0], %g2
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retl
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sub %o0, 1, %o0
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mzero_found_it:
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retl
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sub %o0, 2, %o0
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memscan:
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__memscan_generic:
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/* %o0 = addr, %o1 = c, %o2 = size */
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cmp %o2, 0
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bne,a 0f
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ldub [%o0], %g2
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b,a 2f
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1:
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ldub [%o0], %g2
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0:
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cmp %g2, %o1
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be 2f
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addcc %o2, -1, %o2
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bne 1b
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add %o0, 1, %o0
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2:
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retl
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nop
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