| 1 | /* |
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| 2 | * Public domain. |
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| 3 | * |
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| 4 | */ |
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| 5 | |
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| 6 | #include <machine/asm.h> |
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| 7 | |
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| 8 | RCSID("$NetBSD: s_log1p.S,v 1.7 1995/05/09 00:10:58 jtc Exp $" ) |
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| 9 | |
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| 10 | .section .rodata |
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| 11 | |
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| 12 | .align ALIGNARG(4) |
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| 13 | /* The fyl2xp1 can only be used for values in |
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| 14 | -1 + sqrt(2) / 2 <= x <= 1 - sqrt(2) / 2 |
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| 15 | 0.29 is a safe value. |
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| 16 | */ |
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| 17 | limit: .quad 0x947ae147ae147ae1 /* 0.29 */ |
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| 18 | .short 0x3ffd |
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| 19 | /* Please note: we use a double value here. Since 1.0 has |
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| 20 | an exact representation this does not effect the accuracy |
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| 21 | but it helps to optimize the code. */ |
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| 22 | one: .double 1.0 |
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| 23 | |
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| 24 | /* |
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| 25 | * Use the fyl2xp1 function when the argument is in the range -0.29 to 0.29, |
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| 26 | * otherwise fyl2x with the needed extra computation. |
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| 27 | */ |
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| 28 | #ifdef PIC |
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| 29 | #define MO(op) op##(%rip) |
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| 30 | #else |
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| 31 | #define MO(op) op |
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| 32 | #endif |
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| 33 | |
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| 34 | .text |
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| 35 | ENTRY(__log1pl) |
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| 36 | fldln2 |
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| 37 | |
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| 38 | fldt 8(%rsp) |
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| 39 | |
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| 40 | fxam |
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| 41 | fnstsw |
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| 42 | fld %st |
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| 43 | testb $1, %ah |
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| 44 | jnz 3f // in case x is NaN or ħInf |
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| 45 | 4: |
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| 46 | fabs |
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| 47 | fldt MO(limit) |
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| 48 | fcompp |
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| 49 | fnstsw |
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| 50 | andb $1,%ah |
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| 51 | jz 2f |
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| 52 | |
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| 53 | movzwl 8+8(%rsp), %eax |
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| 54 | xorb $0x80, %ah |
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| 55 | cmpl $0xc040, %eax |
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| 56 | jae 5f |
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| 57 | |
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| 58 | faddl MO(one) |
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| 59 | 5: fyl2x |
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| 60 | ret |
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| 61 | |
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| 62 | 2: fyl2xp1 |
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| 63 | ret |
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| 64 | |
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| 65 | 3: testb $4, %ah |
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| 66 | jnz 4b // in case x is ħInf |
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| 67 | fstp %st(1) |
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| 68 | fstp %st(1) |
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| 69 | fadd %st(0) |
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| 70 | ret |
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| 71 | |
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| 72 | END (__log1pl) |
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| 73 | |
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