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1 /*
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2
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3 Package: dyncall
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4 Library: dyncallback
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5 File: dyncallback/dyncall_callback_arm32_arm_gas.s
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6 Description: Callback Thunk - Implementation for ARM32 (ARM mode)
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7 License:
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8
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9 Copyright (c) 2007-2011 Daniel Adler <dadler@uni-goettingen.de>,
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10 Tassilo Philipp <tphilipp@potion-studios.com>
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11
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12 Permission to use, copy, modify, and distribute this software for any
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13 purpose with or without fee is hereby granted, provided that the above
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14 copyright notice and this permission notice appear in all copies.
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15
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16 THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
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17 WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
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18 MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
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19 ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
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20 WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
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21 ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
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22 OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
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23
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24 */
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25
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26
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27 .text
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28 .code 32 /* ARM mode */
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29
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30 .globl dcCallbackThunkEntry
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31
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32 /* sizes */
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33 .set DCThunk_size , 8
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34 .set DCArgs_size , 24
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35 .set DCValue_size , 8
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36
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37 /* struct DCCallback offsets and size */
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38 .set CTX_thunk , 0
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39 .set CTX_handler , 12
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40 .set CTX_userdata , 16
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41 .set DCCallback_size, 20
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42
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43
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44 /* Called by thunk - thunk stores pointer to DCCallback in r12 */
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45 dcCallbackThunkEntry:
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46
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47 /* Prolog. This function never needs to spill inside its prolog, so just store the permanent registers. */
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48 stmdb %r13, {%r4-%r11, %r13, %r14} /* Permanent registers and stack pointer, etc... -> save area on stack (except counter). */
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49 mov %r11, %r13 /* Set frame pointer. */
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50 sub %r13, %r13, #40 /* Adjust stack pointer. */
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51
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52 /* Grab arguments. */
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53 mov %r4, #0
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54 stmdb %r13!, {%r0-%r4, %r11} /* Spill first 4 args to DCArgs, along with reg_count and (stack) pointer to remaining args. */
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55
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56 /* Prepare callback handler call. */
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57 mov %r0, %r12 /* Parameter 0 (r0) = DCCallback pointer (r12, pointer to thunk). */
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58 mov %r1, %r13 /* Parameter 1 (r1) = DCArgs pointer (r13, stack pointer). */
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59 sub %r13, %r13, #DCValue_size /* Make room for return value. */
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60 mov %r2, %r13 /* Parameter 2 (r2) = results pointer. */
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61 ldr %r3, [%r12, #CTX_userdata] /* Parameter 3 (r3) = userdata pointer. */
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62
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63 /* Call. */
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64 ldr %r4, [%r12, #CTX_handler] /* Load callback handler pointer into r4. */
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65 mov %r14, %r15 /* Branch return address(r15) -> link register (r14) -- r15 always points to address of current + 2 instructions (= Epilog code). */
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66 bx %r4 /* Call. */
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67
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68 /* Return value. */
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69 ldmia %r13, {%r0, %r1} /* Load return value in r0 and r1. */
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70
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71 /* Epilog. */
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72 ldmdb %r11, {%r4-%r11, %r13, %r15} /* Restore permanent registers (restore stack ptr and program counter).@@@db not needed since we rewrite r13? */
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73
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