apply-hack.ppc.sysv.s

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/* apply-hack.ppc.s
;
; Copyright (c) 2007, Felix L. Winkelmann
; Copyright (c) 2008, The Chicken Team
; All rights reserved.		
;
; Redistribution and use in source and binary forms, with or without modification, are permitted provided that the following
; conditions are met:
;
;   Redistributions of source code must retain the above copyright notice, this list of conditions and the following
;     disclaimer. 
;   Redistributions in binary form must reproduce the above copyright notice, this list of conditions and the following
;     disclaimer in the documentation and/or other materials provided with the distribution. 
;   Neither the name of the author nor the names of its contributors may be used to endorse or promote
;     products derived from this software without specific prior written permission. 
;
; THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND ANY EXPRESS
; OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY
; AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDERS OR
; CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
; CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
; SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
; THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR
; OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
; POSSIBILITY OF SUCH DAMAGE.
*/

	.text

	.globl _C_do_apply_hack
	.align 2

_C_do_apply_hack:
	mr %r13, %r3		/* r13=proc */
	mr %r14, %r4		/* r14=buf */
	mr %r15, %r5		/* r15=count */
	li %r16, 8		/* Assume count >= 8 */
	cmpwi %r15, 8
	bge l1
	li %r3, 8		/* offset is (8 - count) * 4 */
	mr %r16, %r15		/* Remember count */
	sub %r15, %r3, %r15
	slwi %r15, %r15, 2
	bl l2			/* compute branch address */
l2:	mflr %r4
	add %r15, %r4, %r15
	addi %r15, %r15, (l1 - l2)@l
	mtctr %r15
	bctr
l1:	lwz %r10, 28(%r14)	/* load register arguments */
	lwz %r9, 24(%r14)
	lwz %r8, 20(%r14)
	lwz %r7, 16(%r14)
	lwz %r6, 12(%r14)
	lwz %r5, 8(%r14)
	lwz %r4, 4(%r14)
	lwz %r3, 0(%r14)
	lwz %r15, 4(%r1)	/* LR (needed?) */
	stw %r15, -4(%r14)
	lwz %r15, 0(%r1)	/* Back chain (needed?) */
	stw %r15, -8(%r14)
	slwi %r16, %r16, 2      /* (Count * 4, but never > 8) can be shifted from params list */
	add %r1, %r14, %r16 	/* set frame-pointer to faked frame */
	subi %r1, %r1, 8	/* Add LR and back chain save word */
	mtctr %r13		/* jump to proc */
	bctr