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jeremybenn |
/* longjmp.S. Implementation of longjmp.
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Copyright (C) 2010, Embecosm Limited
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Contributor Jeremy Bennett
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This file is part of Newlib.
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This program 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 Free
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Software Foundation; either version 3 of the License, or (at your option)
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any later version.
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This program is distributed in the hope that it will be useful, but WITHOUT
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ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
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more details.
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You should have received a copy of the GNU General Public License along
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with this program. If not, see . */
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/* -------------------------------------------------------------------------- */
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/* This program is commented throughout in a fashion suitable for processing
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with Doxygen. */
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/* -------------------------------------------------------------------------- */
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/* -------------------------------------------------------------------------- */
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/*!_longjmp
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All processor state is restored from the buffer provided. We need not restore
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r0 (it will always be zero) and we need not restore r11 (it will always be
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overridden here).
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We need to take some care, since we cannot restore r3 until all other
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registers are restore, and the value of r4 must first be saved in r11,
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modifying it if its value is zero.
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@todo We should prefer to save and restore the status register, but this is
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not directly possible in user code. There is some merit in code to
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set the flag, since in compiled C code, that might be expected to hold
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a value. We leave a space for this information for future enhancement.
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@param[out] env(r3) A buffer from which to restore all the current
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processor state.
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@param[in] val(r4) A value to return
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@return val, unless val is zero, in which case 1 is returned.
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/* -------------------------------------------------------------------------- */
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.align 4
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.global _longjmp
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.type _longjmp,@function
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_longjmp:
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/* Sort out the return value */
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l.sfne r4,r0
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l.bf 1f
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l.nop
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l.j 2f
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l.addi r11,r0,1 /* 1 as result */
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1: l.addi r11,r4,0 /* val as result */
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/* Restore all the other registers, leaving r3 to last. */
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2: l.lwz r31,120(r3)
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l.lwz r30,116(r3)
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l.lwz r29,112(r3)
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l.lwz r28,108(r3)
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l.lwz r27,104(r3)
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l.lwz r26,100(r3)
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l.lwz r25,96(r3)
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l.lwz r24,92(r3)
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l.lwz r23,88(r3)
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l.lwz r22,84(r3)
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l.lwz r21,80(r3)
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l.lwz r20,76(r3)
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l.lwz r19,72(r3)
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l.lwz r18,68(r3)
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l.lwz r17,64(r3)
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l.lwz r16,60(r3)
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l.lwz r15,56(r3)
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l.lwz r14,52(r3)
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l.lwz r13,48(r3)
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l.lwz r12,44(r3)
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l.lwz r10,40(r3) /* Omit r11 */
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l.lwz r9,36(r3)
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l.lwz r8,32(r3)
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l.lwz r7,28(r3)
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l.lwz r6,24(r3)
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l.lwz r5,20(r3)
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l.lwz r4,16(r3)
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l.lwz r2,8(r3) /* Skip r3 */
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l.lwz r1,4(r3) /* Slot 0 saved for flag in future */
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l.lwz r3,12(r3) /* Now safe */
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/* Result is already in r11. Having restored r9, it will appear as
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though we have returned from the earlier call to _setjmp. The
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non-zero result gives it away though. */
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l.jr r9
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l.nop
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.size _longjmp, .-_longjmp
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