/*
            Copyright Oliver Kowalke 2009.
   Distributed under the Boost Software License, Version 1.0.
      (See accompanying file LICENSE_1_0.txt or copy at
          http://www.boost.org/LICENSE_1_0.txt)
*/

/*******************************************************
 *                                                     *
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 *  |  0  |  1  |  2  |  3  |  4  |  5  |  6  |  7  |  *
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 *  |  0  |  4  |  8  |  12 |  16 |  20 |  24 |  28 |  *
 *  -------------------------------------------------  *
 *  |    TOC    |    R14    |    R15    |    R16    |  *
 *  -------------------------------------------------  *
 *  -------------------------------------------------  *
 *  |  8  |  9  |  10 |  11 |  12 |  13 |  14 |  15 |  *
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 *  |  32 |  36 |  40 |  44 |  48 |  52 |  56 |  60 |  *
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 *  |    R17    |    R18    |     R19   |    R20    |  *
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 *  |  16 |  17 |  18 |  19 |  20 |  21 |  22 |  23 |  *
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 *  |  64 |  68 |  72 |  76 |  80 |  84 |  88 |  92 |  *
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 *  |    R21    |    R22    |    R23    |    R24    |  *
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 *  |  24 |  25 |  26 |  27 |  28 |  29 |  30 |  31 |  *
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 *  |  96 | 100 | 104 | 108 | 112 | 116 | 120 | 124 |  *
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 *  |    R25    |    R26    |    R27    |    R28    |  *
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 *  |  32 |  33 |  34 |  35 |  36 |  37 |  38 |  39 |  *
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 *  | 128 | 132 | 136 | 140 | 144 | 148 | 152 | 156 |  *
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 *  |    R29    |    R30    |    R31    |   hidden  |  *
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 *  | 160 | 164 | 168 | 172 | 176 | 180 | 184 | 188 |  *
 *  -------------------------------------------------  *
 *  |     CR    |     LR    |     PC    | back-chain|  *
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 *  -------------------------------------------------  *
 *  | 192 | 196 | 200 | 204 | 208 | 212 | 216 | 220 |  *
 *  -------------------------------------------------  *
 *  |  cr saved |  lr saved |  compiler |   linker  |  *
 *  -------------------------------------------------  *
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 *  |  56 |  57 |  58 |  59 |  60 |  61 |  62 |  63 |  *
 *  -------------------------------------------------  *
 *  | 224 | 228 | 232 | 236 | 240 | 244 | 248 | 252 |  *
 *  -------------------------------------------------  *
 *  | TOC saved |    FCTX   |    DATA   |           |  *
 *  -------------------------------------------------  *
 *                                                     *
 *******************************************************/

    .file "make_ppc64_sysv_xcoff_gas.S"
    .toc
    .csect .text[PR], 5
    .align 2
    .globl  make_fcontext[DS]
    .globl .make_fcontext
    .csect  make_fcontext[DS], 3
make_fcontext:
    .llong .make_fcontext[PR], TOC[tc0], 0
    .csect .text[PR], 5
.make_fcontext:
    # save return address into R6
    mflr  6

    # first arg of make_fcontext() == top address of context-function
    # shift address in R3 to lower 16 byte boundary
    clrrdi  3, 3, 4

    # reserve space for context-data on context-stack
    # including 64 byte of linkage + parameter area (R1 % 16 == 0)
    subi  3, 3, 248

    # third arg of make_fcontext() == address of context-function descriptor
    ld   4, 0(5)
    std  4, 176(3)
    # save TOC of context-function
    ld   4, 8(5)
    std  4, 0(3)

    # set back-chain to zero
    li   0, 0
    std  0, 184(3)

    # zero in r3 indicates first jump to context-function
    std  0, 152(3)

    # load LR
    mflr  0
    # jump to label 1
    bl  .Label
.Label:
    # load LR into R4
    mflr  4
    # compute abs address of label .L_finish
    addi  4, 4, .L_finish - .Label
    # restore LR
    mtlr  0
    # save address of finish as return-address for context-function
    # will be entered after context-function returns
    std  4, 168(3)

    # restore return address from R6
    mtlr  6

    blr  # return pointer to context-data

.L_finish:
    # save return address into R0
    mflr  0
    # save return address on stack, set up stack frame
    std  0, 8(1)
    # allocate stack space, R1 % 16 == 0
    stdu  1, -32(1)

    # exit code is zero
    li  3, 0
    # exit application
    bl  ._exit
    nop