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1 /*
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2
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3 Package: dyncall
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4 Library: dyncall
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5 File: dyncall/dyncall_call_arm32_thumb_apple.s
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6 Description: ARM Thumb call kernel implementation for apple assembler.
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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 .thumb
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29 .code 16
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30 .globl _dcCall_arm32_thumb
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31
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32 /* Main dyncall call. */
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33 .thumb_func
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34 _dcCall_arm32_thumb:
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35
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36 /* Prolog. This function never needs to spill inside its prolog, so just store the permanent registers. */
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37 push {r4-r7, r14} /* Frame ptr, permanent registers, link register -> save area on stack. */
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38 mov r7, r13 /* Set frame ptr. */
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39
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40 /* Call. */
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41 mov r4, r0 /* Move 'fptr' to r4 (1st argument is passed in r0). */
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42
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43 /* Disable 'thumb' address forcing... */
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44
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45 /* mov r0, #1 */ /* Assure that LSB is set to 1 (THUMB call). - Not Required and not useful for interworking calls */
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46 /* orr r4, r0 */
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47
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48 mov r5, r1 /* Move 'args' to r5 (2nd argument is passed in r1). */
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49 mov r6, r2 /* Move 'size' to r6 (3rd argument is passed in r2). */
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50
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51 cmp r6, #16 /* Jump to call if no more than 4 arguments. */
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52 ble call
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53
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54 sub r6, #16 /* Size of remaining arguments. */
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55 mov r0, r13 /* Set stack pointer to top of stack. */
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56 sub r0, r0, r6
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57 lsr r0, #3 /* Align stack on 8 byte boundaries. */
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58 lsl r0, #3
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59 mov r13, r0
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60
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61 add r1, #16 /* Let r1 point to remaining arguments. */
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62 mov r2, #0 /* Init byte counter to 0. */
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63 .thumb_func
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64 pushArgs:
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65 ldrb r3, [r1, r2] /* Load a byte into r3. */
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66 strb r3, [r0, r2] /* Push byte onto stack. */
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67 add r2, r2, #1 /* Increment byte counter. */
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68 cmp r2, r6
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69 bne pushArgs
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70 .thumb_func
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71 call:
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72 ldmia r5!, {r0-r3} /* Load first 4 arguments for new call into r0-r3. */
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73
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74 /* 'blx %r4' workaround for ARMv4t in THUMB: */
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75 blx r4 /* Branch and force THUMB-mode return (LR bit 0 set). */
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76
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77 /* Epilog. */
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78 mov r13, r7 /* Reset stack ptr. */
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79 pop {r4-r7, r15} /* Restore permanent registers and program counter. (Force a stay in THUMB in ARMv4, whether ARMv5 can return in ARM or THUMB depending on the bit 0. */
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80
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