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0
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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_callback_x86_8a.s
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6 Description: x86 abi callback kernel implementation for Plan9's 8a
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7 License:
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8
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9 Copyright (c) 2013 Tassilo Philipp <tphilipp@potion-studios.com>
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10
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11 Permission to use, copy, modify, and distribute this software for any
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12 purpose with or without fee is hereby granted, provided that the above
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13 copyright notice and this permission notice appear in all copies.
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14
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15 THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
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16 WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
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17 MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
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18 ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
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19 WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
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20 ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
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21 OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
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22
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23 */
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24
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25
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26 TEXT dcCallbackThunkEntry(SB), $0
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27
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28 /* input:
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29 AX -> thunk
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30 AX+16 -> cb handler
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31 AX+20 -> dcargsvt
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32 AX+24 -> stack cleanup <-- not used for stack cleaning as caller cleans up,
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33 AX+28 -> userdata however reused as flag to indicate 64bit return value)
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34 */
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35
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36 /* prolog */
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37 MOVL SP, BP
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38
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39 /* copy of DCargs passed to cb handler */
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40 PUSHL $0 /* fast_count (unused on plan9, but using shared x86 dcargs struct) */
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41 SUBL $8, SP /* skip fast_data[] ( " ) */
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42 LEAL 8(BP), CX /* ptr to args on stack, depending if return val is 64bit ... */
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43 CMPL 24(AX), $1
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44 JEQ is_ll_ret
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45 LEAL 4(BP), CX /* ... or not */
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46 is_ll_ret:
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47 PUSHL CX
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48 PUSHL 20(AX) /* args vtable ptr */
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49 MOVL SP, CX /* DCArgs-ptr (data pushed above) */
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50
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51 /* space for return value (long long) */
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52 PUSHL $0
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53 PUSHL $0
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54 MOVL SP, DX /* retval ptr */
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55
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56 /* call the handler */
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57 PUSHL 28(AX) /* userdata for handler */
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58 PUSHL DX /* results */
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59 PUSHL CX /* args */
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60 PUSHL AX /* callback obj */
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61 MOVL 16(AX), AX
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62 CALL AX
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63
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64 /* copy retval from ptr on stack to AX or stack space if 64bit */
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65 MOVL 8(SP), BX /* ptr to retval */
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66 CMPL AX, $0x6c /* 'l' @@@ compares return from handler, might be different from sig - design currently in discussion */
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67 JEQ ll_ret;
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68 CMPL AX, $0x4c /* 'L' @@@ compares return from handler, might be different from sig - design currently in discussion */
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69 JEQ ll_ret;
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70 CMPL AX, $0x66 /* 'f' @@@ compares return from handler, might be different from sig - design currently in discussion */
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71 JEQ f_ret;
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72 CMPL AX, $0x64 /* 'd' @@@ compares return from handler, might be different from sig - design currently in discussion */
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73 JEQ d_ret;
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74 JMP other_ret
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75
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76 ll_ret:
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77 MOVL 48(SP), DX /* ptr to ret address space; 48 = stack size + caller's ret address */
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78 MOVL (BX), CX
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79 MOVL CX, (DX)
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80 MOVL 4(BX), CX
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81 MOVL CX, 4(DX)
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82 JMP cont_ret
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83
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84 f_ret:
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85 FMOVF (BX), F0
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86 JMP cont_ret
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87
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88 d_ret:
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89 FMOVD (BX), F0
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90 JMP cont_ret
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91
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92 other_ret:
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93 MOVL (BX), AX /* 32bit non-fp are returned in AX */
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94
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95 /* epilog */
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96 cont_ret:
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97 ADDL $44, SP /* Cleanup stack */
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98 POPL CX /* hack to emulate RET without getting overly strict */
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99 JMP CX /* 'unbalanced PUSH/POP' warning/error from 8l */
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100
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