| 1 | #include <cstdint> |
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| 2 | |
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| 3 | struct alignas(16) float80_raw { |
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| 4 | uint64_t mantissa; |
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| 5 | uint16_t sign_exp; |
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| 6 | }; |
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| 7 | |
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| 8 | int main() { |
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| 9 | float80_raw st[] = { |
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| 10 | {.mantissa: 0x8000000000000000, .sign_exp: 0x4000}, // +2.0 |
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| 11 | {.mantissa: 0x3f00000000000000, .sign_exp: 0x0000}, // 1.654785e-4932 (denormal) |
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| 12 | {.mantissa: 0x0000000000000000, .sign_exp: 0x0000}, // +0 |
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| 13 | {.mantissa: 0x0000000000000000, .sign_exp: 0x8000}, // -0 |
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| 14 | {.mantissa: 0x8000000000000000, .sign_exp: 0x7fff}, // +inf |
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| 15 | {.mantissa: 0x8000000000000000, .sign_exp: 0xffff}, // -inf |
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| 16 | {.mantissa: 0xc000000000000000, .sign_exp: 0xffff}, // nan |
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| 17 | // st7 will be freed to test tag word better |
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| 18 | {.mantissa: 0x0000000000000000, .sign_exp: 0x0000}, // +0 |
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| 19 | }; |
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| 20 | |
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| 21 | // unmask divide-by-zero exception |
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| 22 | uint16_t cw = 0x037b; |
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| 23 | // used as single-precision float |
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| 24 | uint32_t zero = 0; |
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| 25 | |
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| 26 | asm volatile( |
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| 27 | "finit\n\t" |
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| 28 | "fldcw %1\n\t" |
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| 29 | // load on stack in reverse order to make the result easier to read |
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| 30 | "fldt 0x70(%0)\n\t" |
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| 31 | "fldt 0x60(%0)\n\t" |
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| 32 | "fldt 0x50(%0)\n\t" |
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| 33 | "fldt 0x40(%0)\n\t" |
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| 34 | "fldt 0x30(%0)\n\t" |
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| 35 | "fldt 0x20(%0)\n\t" |
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| 36 | "fldt 0x10(%0)\n\t" |
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| 37 | "fldt 0x00(%0)\n\t" |
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| 38 | // free st7 |
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| 39 | "ffree %%st(7)\n\t" |
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| 40 | // this should trigger a divide-by-zero |
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| 41 | "fdivs (%2)\n\t" |
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| 42 | "int3\n\t" |
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| 43 | : |
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| 44 | : "a" (st), "m" (cw), "b" (&zero) |
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| 45 | : "st" |
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| 46 | ); |
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| 47 | |
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| 48 | return 0; |
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| 49 | } |
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| 50 | |
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