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trampoline.S revision 1.1.1.3.4.2 
      1 /* libgcc routines for RL78
      2    Copyright (C) 2011-2018 Free Software Foundation, Inc.
      3    Contributed by Red Hat.
      4 
      5    This file is part of GCC.
      6 
      7    GCC is free software; you can redistribute it and/or modify it
      8    under the terms of the GNU General Public License as published
      9    by the Free Software Foundation; either version 3, or (at your
     10    option) any later version.
     11 
     12    GCC is distributed in the hope that it will be useful, but WITHOUT
     13    ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
     14    or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public
     15    License for more details.
     16 
     17    Under Section 7 of GPL version 3, you are granted additional
     18    permissions described in the GCC Runtime Library Exception, version
     19    3.1, as published by the Free Software Foundation.
     20 
     21    You should have received a copy of the GNU General Public License and
     22    a copy of the GCC Runtime Library Exception along with this program;
     23    see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see
     24    <http://www.gnu.org/licenses/>.  */
     25 
     26 /* RL78 Trampoline support
     27 
     28   Since the RL78's RAM is not in the first 64k, we cannot "just" use a
     29   function pointer to point to a trampoline on the stack.  So, we
     30   create N fixed trampolines that read from an array, and allocate
     31   them as needed.
     32 
     33 */
     34 
     35 #include "vregs.h"
     36 
     37 	.data
     38 	.p2align	1
     39 trampoline_array:
     40 
     41 	.macro stub n
     42 
     43 	.text
     44 trampoline_\n:
     45         .type   trampoline_\n, @function
     46 	movw	ax, !trampoline_chain_\n
     47 	movw	r14, ax
     48 	movw	ax, !trampoline_addr_\n
     49 	br	ax
     50 	.size	trampoline_\n, .-trampoline_\n
     51 
     52 	.data
     53 trampoline_frame_\n:
     54 	.short	0
     55 trampoline_stub_\n:
     56 	.short	trampoline_\n
     57 trampoline_chain_\n:
     58 	.short	0
     59 trampoline_addr_\n:
     60 	.short	0
     61 
     62 #define TO_FRAME 0
     63 #define TO_STUB  2
     64 #define TO_CHAIN 4
     65 #define TO_ADDR  6
     66 #define TO_SIZE  8
     67 
     68 	.endm
     69 
     70 	stub	0
     71 	stub	1
     72 	stub	2
     73 	stub	3
     74 	stub	4
     75 	stub	5
     76 
     77 trampoline_array_end:
     78 
     79 /* Given the function pointer in R8 and the static chain
     80    pointer in R10, allocate a trampoline and return its address in
     81    R8. */
     82 
     83 START_FUNC ___trampoline_init
     84 	movw	hl, #trampoline_array
     85 
     86 1:	movw	ax, [hl + TO_ADDR]
     87 	cmpw	ax, #0
     88 	bz	$2f
     89 
     90 	movw	ax, hl
     91 	addw	ax, #TO_SIZE
     92 	movw	hl, ax
     93 	cmpw	ax, #trampoline_array_end
     94 	bnz	$1b
     95 	brk			; no more slots?
     96 
     97 2:	movw	ax, r8
     98 	movw	[hl + TO_ADDR], ax
     99 	movw	ax, r10
    100 	movw	[hl + TO_CHAIN], ax
    101 	movw	ax, sp
    102 	movw	[hl + TO_FRAME], ax
    103 
    104 	movw	ax, [hl + TO_STUB]
    105 	movw	r8, ax
    106 	ret
    107 END_FUNC ___trampoline_init
    108 
    109 
    110 START_FUNC ___trampoline_uninit
    111 	movw	hl, #trampoline_array
    112 	movw	ax, sp
    113 	movw	bc, ax
    114 
    115 1:	movw	ax, [hl + TO_FRAME]
    116 	cmpw	ax, bc
    117 	bc	$2f
    118 
    119 	clrw	ax
    120 	movw	[hl + TO_ADDR], ax
    121 
    122 2:	movw	ax, hl
    123 	addw	ax, #TO_SIZE
    124 	movw	hl, ax
    125 	cmpw	ax, #trampoline_array_end
    126 	bnz	$1b
    127 
    128 	ret
    129 END_FUNC ___trampoline_uninit
    130