173 lines
4.1 KiB
ArmAsm
173 lines
4.1 KiB
ArmAsm
; Copyright (C) 2011-2018 Free Software Foundation, Inc.
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; Contributed by Red Hat.
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;
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; This file is free software; you can redistribute it and/or modify it
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; under the terms of the GNU General Public License as published by the
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; Free Software Foundation; either version 3, or (at your option) any
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; later version.
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;
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; This file is distributed in the hope that it will be useful, but
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; WITHOUT ANY WARRANTY; without even the implied warranty of
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; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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; General Public License for more details.
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;
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; Under Section 7 of GPL version 3, you are granted additional
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; permissions described in the GCC Runtime Library Exception, version
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; 3.1, as published by the Free Software Foundation.
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;
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; You should have received a copy of the GNU General Public License and
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; a copy of the GCC Runtime Library Exception along with this program;
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; see the files COPYING3 and COPYING.RUNTIME respectively. If not, see
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; <http://www.gnu.org/licenses/>.
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#include "vregs.h"
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.text
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;; int __cmpsi2 (signed long A, signed long B)
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;;
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;; Performs a signed comparison of A and B.
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;; If A is less than B it returns 0. If A is greater
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;; than B it returns 2. If they are equal it returns 1.
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START_FUNC ___cmpsi2
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;; A is at [sp+4]
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;; B is at [sp+8]
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;; Result put in R8
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;; Initialise default return value.
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onew bc
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;; Compare the high words.
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movw ax, [sp + 10]
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movw de, ax
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movw ax, [sp + 6]
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cmpw ax, de
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skz
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br !!.Lconvert_to_signed
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.Lcompare_bottom_words:
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;; The top words are equal - compare the bottom words.
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;; Note - code from __ucmpsi2 branches into here.
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movw ax, [sp + 8]
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movw de, ax
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movw ax, [sp + 4]
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cmpw ax, de
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sknz
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br !!.Lless_than_or_greater_than
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;; The words are equal - return 1.
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;; Note - we could branch to the return code at the end of the
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;; function but a branch instruction takes 4 bytes, and the
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;; return sequence itself is only 4 bytes long...
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movw ax, bc
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movw r8, ax
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ret
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.Lconvert_to_signed:
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;; The top words are different. Unfortunately the comparison
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;; is always unsigned, so to get a signed result we XOR the CY
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;; flag with the top bits of AX and DE.
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xor1 cy, a.7
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mov a, d
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xor1 cy, a.7
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;; Fall through.
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.Lless_than_or_greater_than:
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;; We now have a signed less than/greater than result in CY.
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;; Return 0 for less than, 2 for greater than.
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;; Note - code from __ucmpsi2 branches into here.
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incw bc
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sknc
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clrw bc
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;; Get the result value, currently in BC, into r8
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movw ax, bc
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movw r8, ax
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ret
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END_FUNC ___cmpsi2
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;; ------------------------------------------------------
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;; int __ucmpsi2 (unsigned long A, unsigned long B)
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;;
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;; Performs an unsigned comparison of A and B.
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;; If A is less than B it returns 0. If A is greater
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;; than B it returns 2. If they are equal it returns 1.
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START_FUNC ___ucmpsi2
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;; A is at [sp+4]
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;; B is at [sp+8]
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;; Result put in R8..R9
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;; Initialise default return value.
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onew bc
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;; Compare the high words.
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movw ax, [sp + 10]
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movw de, ax
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movw ax, [sp + 6]
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cmpw ax, de
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skz
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;; Note: These branches go into the __cmpsi2 code!
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br !!.Lless_than_or_greater_than
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br !!.Lcompare_bottom_words
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END_FUNC ___ucmpsi2
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;; ------------------------------------------------------
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;; signed int __gcc_bcmp (const unsigned char *s1, const unsigned char *s2, size_t size)
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;; Result is negative if S1 is less than S2,
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;; positive if S1 is greater, 0 if S1 and S2 are equal.
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START_FUNC __gcc_bcmp
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;; S1 is at [sp+4]
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;; S2 is at [sp+6]
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;; SIZE is at [sp+8]
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;; Result in r8/r9
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movw r10, #0
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1:
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;; Compare R10 against the SIZE parameter
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movw ax, [sp+8]
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subw ax, r10
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sknz
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br !!1f
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;; Load S2[r10] into R8
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movw ax, [sp+6]
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addw ax, r10
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movw hl, ax
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mov a, [hl]
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mov r8, a
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;; Load S1[r10] into A
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movw ax, [sp+4]
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addw ax, r10
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movw hl, ax
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mov a, [hl]
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;; Increment offset
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incw r10
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;; Compare loaded bytes
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cmp a, r8
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sknz
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br !!1b
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;; They differ. Subtract *S2 from *S1 and return as the result.
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mov x, a
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mov a, #0
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mov r9, #0
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subw ax, r8
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1:
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movw r8, ax
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ret
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END_FUNC __gcc_bcmp
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