i386: move math-emu

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

1 files changed, 708 insertions, 0 deletions

diff --git a/arch/x86/math-emu/reg_round.S b/arch/x86/math-emu/reg_round.S
new file mode 100644
index 000000000000..d1d4e48b4f67
--- /dev/null
+++ b/arch/x86/math-emu/reg_round.S
@@ -0,0 +1,708 @@
+        .file "reg_round.S"
+/*---------------------------------------------------------------------------+
+ |  reg_round.S                                                              |
+ |                                                                           |
+ | Rounding/truncation/etc for FPU basic arithmetic functions.               |
+ |                                                                           |
+ | Copyright (C) 1993,1995,1997                                              |
+ |                       W. Metzenthen, 22 Parker St, Ormond, Vic 3163,      |
+ |                       Australia.  E-mail billm@suburbia.net               |
+ |                                                                           |
+ | This code has four possible entry points.                                 |
+ | The following must be entered by a jmp instruction:                       |
+ |   fpu_reg_round, fpu_reg_round_sqrt, and fpu_Arith_exit.                  |
+ |                                                                           |
+ | The FPU_round entry point is intended to be used by C code.               |
+ | From C, call as:                                                          |
+ |  int FPU_round(FPU_REG *arg, unsigned int extent, unsigned int control_w) |
+ |                                                                           |
+ |    Return value is the tag of the answer, or-ed with FPU_Exception if     |
+ |    one was raised, or -1 on internal error.                               |
+ |                                                                           |
+ | For correct "up" and "down" rounding, the argument must have the correct  |
+ | sign.                                                                     |
+ |                                                                           |
+ +---------------------------------------------------------------------------*/
+
+/*---------------------------------------------------------------------------+
+ | Four entry points.                                                        |
+ |                                                                           |
+ | Needed by both the fpu_reg_round and fpu_reg_round_sqrt entry points:     |
+ |  %eax:%ebx  64 bit significand                                            |
+ |  %edx       32 bit extension of the significand                           |
+ |  %edi       pointer to an FPU_REG for the result to be stored             |
+ |  stack      calling function must have set up a C stack frame and         |
+ |             pushed %esi, %edi, and %ebx                                   |
+ |                                                                           |
+ | Needed just for the fpu_reg_round_sqrt entry point:                       |
+ |  %cx  A control word in the same format as the FPU control word.          |
+ | Otherwise, PARAM4 must give such a value.                                 |
+ |                                                                           |
+ |                                                                           |
+ | The significand and its extension are assumed to be exact in the          |
+ | following sense:                                                          |
+ |   If the significand by itself is the exact result then the significand   |
+ |   extension (%edx) must contain 0, otherwise the significand extension    |
+ |   must be non-zero.                                                       |
+ |   If the significand extension is non-zero then the significand is        |
+ |   smaller than the magnitude of the correct exact result by an amount     |
+ |   greater than zero and less than one ls bit of the significand.          |
+ |   The significand extension is only required to have three possible       |
+ |   non-zero values:                                                        |
+ |       less than 0x80000000  <=> the significand is less than 1/2 an ls    |
+ |                                 bit smaller than the magnitude of the     |
+ |                                 true exact result.                        |
+ |         exactly 0x80000000  <=> the significand is exactly 1/2 an ls bit  |
+ |                                 smaller than the magnitude of the true    |
+ |                                 exact result.                             |
+ |    greater than 0x80000000  <=> the significand is more than 1/2 an ls    |
+ |                                 bit smaller than the magnitude of the     |
+ |                                 true exact result.                        |
+ |                                                                           |
+ +---------------------------------------------------------------------------*/
+
+/*---------------------------------------------------------------------------+
+ |  The code in this module has become quite complex, but it should handle   |
+ |  all of the FPU flags which are set at this stage of the basic arithmetic |
+ |  computations.                                                            |
+ |  There are a few rare cases where the results are not set identically to  |
+ |  a real FPU. These require a bit more thought because at this stage the   |
+ |  results of the code here appear to be more consistent...                 |
+ |  This may be changed in a future version.                                 |
+ +---------------------------------------------------------------------------*/
+
+
+#include "fpu_emu.h"
+#include "exception.h"
+#include "control_w.h"
+
+/* Flags for FPU_bits_lost */
+#define LOST_DOWN       $1
+#define LOST_UP         $2
+
+/* Flags for FPU_denormal */
+#define DENORMAL        $1
+#define UNMASKED_UNDERFLOW $2
+
+
+#ifndef NON_REENTRANT_FPU
+/*      Make the code re-entrant by putting
+        local storage on the stack: */
+#define FPU_bits_lost   (%esp)
+#define FPU_denormal    1(%esp)
+
+#else
+/*      Not re-entrant, so we can gain speed by putting
+        local storage in a static area: */
+.data
+        .align 4,0
+FPU_bits_lost:
+        .byte   0
+FPU_denormal:
+        .byte   0
+#endif /* NON_REENTRANT_FPU */
+
+
+.text
+.globl fpu_reg_round
+.globl fpu_Arith_exit
+
+/* Entry point when called from C */
+ENTRY(FPU_round)
+        pushl   %ebp
+        movl    %esp,%ebp
+        pushl   %esi
+        pushl   %edi
+        pushl   %ebx
+
+        movl    PARAM1,%edi
+        movl    SIGH(%edi),%eax
+        movl    SIGL(%edi),%ebx
+        movl    PARAM2,%edx
+
+fpu_reg_round:                  /* Normal entry point */
+        movl    PARAM4,%ecx
+
+#ifndef NON_REENTRANT_FPU
+        pushl   %ebx            /* adjust the stack pointer */
+#endif /* NON_REENTRANT_FPU */ 
+
+#ifdef PARANOID
+/* Cannot use this here yet */
+/*      orl     %eax,%eax */
+/*      jns     L_entry_bugged */
+#endif /* PARANOID */
+
+        cmpw    EXP_UNDER,EXP(%edi)
+        jle     L_Make_denorm                   /* The number is a de-normal */
+
+        movb    $0,FPU_denormal                 /* 0 -> not a de-normal */
+
+Denorm_done:
+        movb    $0,FPU_bits_lost                /* No bits yet lost in rounding */
+
+        movl    %ecx,%esi
+        andl    CW_PC,%ecx
+        cmpl    PR_64_BITS,%ecx
+        je      LRound_To_64
+
+        cmpl    PR_53_BITS,%ecx
+        je      LRound_To_53
+
+        cmpl    PR_24_BITS,%ecx
+        je      LRound_To_24
+
+#ifdef PECULIAR_486
+/* With the precision control bits set to 01 "(reserved)", a real 80486
+   behaves as if the precision control bits were set to 11 "64 bits" */
+        cmpl    PR_RESERVED_BITS,%ecx
+        je      LRound_To_64
+#ifdef PARANOID
+        jmp     L_bugged_denorm_486
+#endif /* PARANOID */ 
+#else
+#ifdef PARANOID
+        jmp     L_bugged_denorm /* There is no bug, just a bad control word */
+#endif /* PARANOID */ 
+#endif /* PECULIAR_486 */
+
+
+/* Round etc to 24 bit precision */
+LRound_To_24:
+        movl    %esi,%ecx
+        andl    CW_RC,%ecx
+        cmpl    RC_RND,%ecx
+        je      LRound_nearest_24
+
+        cmpl    RC_CHOP,%ecx
+        je      LCheck_truncate_24
+
+        cmpl    RC_UP,%ecx              /* Towards +infinity */
+        je      LUp_24
+
+        cmpl    RC_DOWN,%ecx            /* Towards -infinity */
+        je      LDown_24
+
+#ifdef PARANOID
+        jmp     L_bugged_round24
+#endif /* PARANOID */ 
+
+LUp_24:
+        cmpb    SIGN_POS,PARAM5
+        jne     LCheck_truncate_24      /* If negative then  up==truncate */
+
+        jmp     LCheck_24_round_up
+
+LDown_24:
+        cmpb    SIGN_POS,PARAM5
+        je      LCheck_truncate_24      /* If positive then  down==truncate */
+
+LCheck_24_round_up:
+        movl    %eax,%ecx
+        andl    $0x000000ff,%ecx
+        orl     %ebx,%ecx
+        orl     %edx,%ecx
+        jnz     LDo_24_round_up
+        jmp     L_Re_normalise
+
+LRound_nearest_24:
+        /* Do rounding of the 24th bit if needed (nearest or even) */
+        movl    %eax,%ecx
+        andl    $0x000000ff,%ecx
+        cmpl    $0x00000080,%ecx
+        jc      LCheck_truncate_24      /* less than half, no increment needed */
+
+        jne     LGreater_Half_24        /* greater than half, increment needed */
+
+        /* Possibly half, we need to check the ls bits */
+        orl     %ebx,%ebx
+        jnz     LGreater_Half_24        /* greater than half, increment needed */
+
+        orl     %edx,%edx
+        jnz     LGreater_Half_24        /* greater than half, increment needed */
+
+        /* Exactly half, increment only if 24th bit is 1 (round to even) */
+        testl   $0x00000100,%eax
+        jz      LDo_truncate_24
+
+LGreater_Half_24:                       /* Rounding: increment at the 24th bit */
+LDo_24_round_up:
+        andl    $0xffffff00,%eax        /* Truncate to 24 bits */
+        xorl    %ebx,%ebx
+        movb    LOST_UP,FPU_bits_lost
+        addl    $0x00000100,%eax
+        jmp     LCheck_Round_Overflow
+
+LCheck_truncate_24:
+        movl    %eax,%ecx
+        andl    $0x000000ff,%ecx
+        orl     %ebx,%ecx
+        orl     %edx,%ecx
+        jz      L_Re_normalise          /* No truncation needed */
+
+LDo_truncate_24:
+        andl    $0xffffff00,%eax        /* Truncate to 24 bits */
+        xorl    %ebx,%ebx
+        movb    LOST_DOWN,FPU_bits_lost
+        jmp     L_Re_normalise
+
+
+/* Round etc to 53 bit precision */
+LRound_To_53:
+        movl    %esi,%ecx
+        andl    CW_RC,%ecx
+        cmpl    RC_RND,%ecx
+        je      LRound_nearest_53
+
+        cmpl    RC_CHOP,%ecx
+        je      LCheck_truncate_53
+
+        cmpl    RC_UP,%ecx              /* Towards +infinity */
+        je      LUp_53
+
+        cmpl    RC_DOWN,%ecx            /* Towards -infinity */
+        je      LDown_53
+
+#ifdef PARANOID
+        jmp     L_bugged_round53
+#endif /* PARANOID */ 
+
+LUp_53:
+        cmpb    SIGN_POS,PARAM5
+        jne     LCheck_truncate_53      /* If negative then  up==truncate */
+
+        jmp     LCheck_53_round_up
+
+LDown_53:
+        cmpb    SIGN_POS,PARAM5
+        je      LCheck_truncate_53      /* If positive then  down==truncate */
+
+LCheck_53_round_up:
+        movl    %ebx,%ecx
+        andl    $0x000007ff,%ecx
+        orl     %edx,%ecx
+        jnz     LDo_53_round_up
+        jmp     L_Re_normalise
+
+LRound_nearest_53:
+        /* Do rounding of the 53rd bit if needed (nearest or even) */
+        movl    %ebx,%ecx
+        andl    $0x000007ff,%ecx
+        cmpl    $0x00000400,%ecx
+        jc      LCheck_truncate_53      /* less than half, no increment needed */
+
+        jnz     LGreater_Half_53        /* greater than half, increment needed */
+
+        /* Possibly half, we need to check the ls bits */
+        orl     %edx,%edx
+        jnz     LGreater_Half_53        /* greater than half, increment needed */
+
+        /* Exactly half, increment only if 53rd bit is 1 (round to even) */
+        testl   $0x00000800,%ebx
+        jz      LTruncate_53
+
+LGreater_Half_53:                       /* Rounding: increment at the 53rd bit */
+LDo_53_round_up:
+        movb    LOST_UP,FPU_bits_lost
+        andl    $0xfffff800,%ebx        /* Truncate to 53 bits */
+        addl    $0x00000800,%ebx
+        adcl    $0,%eax
+        jmp     LCheck_Round_Overflow
+
+LCheck_truncate_53:
+        movl    %ebx,%ecx
+        andl    $0x000007ff,%ecx
+        orl     %edx,%ecx
+        jz      L_Re_normalise
+
+LTruncate_53:
+        movb    LOST_DOWN,FPU_bits_lost
+        andl    $0xfffff800,%ebx        /* Truncate to 53 bits */
+        jmp     L_Re_normalise
+
+
+/* Round etc to 64 bit precision */
+LRound_To_64:
+        movl    %esi,%ecx
+        andl    CW_RC,%ecx
+        cmpl    RC_RND,%ecx
+        je      LRound_nearest_64
+
+        cmpl    RC_CHOP,%ecx
+        je      LCheck_truncate_64
+
+        cmpl    RC_UP,%ecx              /* Towards +infinity */
+        je      LUp_64
+
+        cmpl    RC_DOWN,%ecx            /* Towards -infinity */
+        je      LDown_64
+
+#ifdef PARANOID
+        jmp     L_bugged_round64
+#endif /* PARANOID */ 
+
+LUp_64:
+        cmpb    SIGN_POS,PARAM5
+        jne     LCheck_truncate_64      /* If negative then  up==truncate */
+
+        orl     %edx,%edx
+        jnz     LDo_64_round_up
+        jmp     L_Re_normalise
+
+LDown_64:
+        cmpb    SIGN_POS,PARAM5
+        je      LCheck_truncate_64      /* If positive then  down==truncate */
+
+        orl     %edx,%edx
+        jnz     LDo_64_round_up
+        jmp     L_Re_normalise
+
+LRound_nearest_64:
+        cmpl    $0x80000000,%edx
+        jc      LCheck_truncate_64
+
+        jne     LDo_64_round_up
+
+        /* Now test for round-to-even */
+        testb   $1,%bl
+        jz      LCheck_truncate_64
+
+LDo_64_round_up:
+        movb    LOST_UP,FPU_bits_lost
+        addl    $1,%ebx
+        adcl    $0,%eax
+
+LCheck_Round_Overflow:
+        jnc     L_Re_normalise
+
+        /* Overflow, adjust the result (significand to 1.0) */
+        rcrl    $1,%eax
+        rcrl    $1,%ebx
+        incw    EXP(%edi)
+        jmp     L_Re_normalise
+
+LCheck_truncate_64:
+        orl     %edx,%edx
+        jz      L_Re_normalise
+
+LTruncate_64:
+        movb    LOST_DOWN,FPU_bits_lost
+
+L_Re_normalise:
+        testb   $0xff,FPU_denormal
+        jnz     Normalise_result
+
+L_Normalised:
+        movl    TAG_Valid,%edx
+
+L_deNormalised:
+        cmpb    LOST_UP,FPU_bits_lost
+        je      L_precision_lost_up
+
+        cmpb    LOST_DOWN,FPU_bits_lost
+        je      L_precision_lost_down
+
+L_no_precision_loss:
+        /* store the result */
+
+L_Store_significand:
+        movl    %eax,SIGH(%edi)
+        movl    %ebx,SIGL(%edi)
+
+        cmpw    EXP_OVER,EXP(%edi)
+        jge     L_overflow
+
+        movl    %edx,%eax
+
+        /* Convert the exponent to 80x87 form. */
+        addw    EXTENDED_Ebias,EXP(%edi)
+        andw    $0x7fff,EXP(%edi)
+
+fpu_reg_round_signed_special_exit:
+
+        cmpb    SIGN_POS,PARAM5
+        je      fpu_reg_round_special_exit
+
+        orw     $0x8000,EXP(%edi)       /* Negative sign for the result. */
+
+fpu_reg_round_special_exit:
+
+#ifndef NON_REENTRANT_FPU
+        popl    %ebx            /* adjust the stack pointer */
+#endif /* NON_REENTRANT_FPU */ 
+
+fpu_Arith_exit:
+        popl    %ebx
+        popl    %edi
+        popl    %esi
+        leave
+        ret
+
+
+/*
+ * Set the FPU status flags to represent precision loss due to
+ * round-up.
+ */
+L_precision_lost_up:
+        push    %edx
+        push    %eax
+        call    set_precision_flag_up
+        popl    %eax
+        popl    %edx
+        jmp     L_no_precision_loss
+
+/*
+ * Set the FPU status flags to represent precision loss due to
+ * truncation.
+ */
+L_precision_lost_down:
+        push    %edx
+        push    %eax
+        call    set_precision_flag_down
+        popl    %eax
+        popl    %edx
+        jmp     L_no_precision_loss
+
+
+/*
+ * The number is a denormal (which might get rounded up to a normal)
+ * Shift the number right the required number of bits, which will
+ * have to be undone later...
+ */
+L_Make_denorm:
+        /* The action to be taken depends upon whether the underflow
+           exception is masked */
+        testb   CW_Underflow,%cl                /* Underflow mask. */
+        jz      Unmasked_underflow              /* Do not make a denormal. */
+
+        movb    DENORMAL,FPU_denormal
+
+        pushl   %ecx            /* Save */
+        movw    EXP_UNDER+1,%cx
+        subw    EXP(%edi),%cx
+
+        cmpw    $64,%cx /* shrd only works for 0..31 bits */
+        jnc     Denorm_shift_more_than_63
+
+        cmpw    $32,%cx /* shrd only works for 0..31 bits */
+        jnc     Denorm_shift_more_than_32
+
+/*
+ * We got here without jumps by assuming that the most common requirement
+ *   is for a small de-normalising shift.
+ * Shift by [1..31] bits
+ */
+        addw    %cx,EXP(%edi)
+        orl     %edx,%edx       /* extension */
+        setne   %ch             /* Save whether %edx is non-zero */
+        xorl    %edx,%edx
+        shrd    %cl,%ebx,%edx
+        shrd    %cl,%eax,%ebx
+        shr     %cl,%eax
+        orb     %ch,%dl
+        popl    %ecx
+        jmp     Denorm_done
+
+/* Shift by [32..63] bits */
+Denorm_shift_more_than_32:
+        addw    %cx,EXP(%edi)
+        subb    $32,%cl
+        orl     %edx,%edx
+        setne   %ch
+        orb     %ch,%bl
+        xorl    %edx,%edx
+        shrd    %cl,%ebx,%edx
+        shrd    %cl,%eax,%ebx
+        shr     %cl,%eax
+        orl     %edx,%edx               /* test these 32 bits */
+        setne   %cl
+        orb     %ch,%bl
+        orb     %cl,%bl
+        movl    %ebx,%edx
+        movl    %eax,%ebx
+        xorl    %eax,%eax
+        popl    %ecx
+        jmp     Denorm_done
+
+/* Shift by [64..) bits */
+Denorm_shift_more_than_63:
+        cmpw    $64,%cx
+        jne     Denorm_shift_more_than_64
+
+/* Exactly 64 bit shift */
+        addw    %cx,EXP(%edi)
+        xorl    %ecx,%ecx
+        orl     %edx,%edx
+        setne   %cl
+        orl     %ebx,%ebx
+        setne   %ch
+        orb     %ch,%cl
+        orb     %cl,%al
+        movl    %eax,%edx
+        xorl    %eax,%eax
+        xorl    %ebx,%ebx
+        popl    %ecx
+        jmp     Denorm_done
+
+Denorm_shift_more_than_64:
+        movw    EXP_UNDER+1,EXP(%edi)
+/* This is easy, %eax must be non-zero, so.. */
+        movl    $1,%edx
+        xorl    %eax,%eax
+        xorl    %ebx,%ebx
+        popl    %ecx
+        jmp     Denorm_done
+
+
+Unmasked_underflow:
+        movb    UNMASKED_UNDERFLOW,FPU_denormal
+        jmp     Denorm_done
+
+
+/* Undo the de-normalisation. */
+Normalise_result:
+        cmpb    UNMASKED_UNDERFLOW,FPU_denormal
+        je      Signal_underflow
+
+/* The number must be a denormal if we got here. */
+#ifdef PARANOID
+        /* But check it... just in case. */
+        cmpw    EXP_UNDER+1,EXP(%edi)
+        jne     L_norm_bugged
+#endif /* PARANOID */
+
+#ifdef PECULIAR_486
+        /*
+         * This implements a special feature of 80486 behaviour.
+         * Underflow will be signalled even if the number is
+         * not a denormal after rounding.
+         * This difference occurs only for masked underflow, and not
+         * in the unmasked case.
+         * Actual 80486 behaviour differs from this in some circumstances.
+         */
+        orl     %eax,%eax               /* ms bits */
+        js      LPseudoDenormal         /* Will be masked underflow */
+#else
+        orl     %eax,%eax               /* ms bits */
+        js      L_Normalised            /* No longer a denormal */
+#endif /* PECULIAR_486 */ 
+
+        jnz     LDenormal_adj_exponent
+
+        orl     %ebx,%ebx
+        jz      L_underflow_to_zero     /* The contents are zero */
+
+LDenormal_adj_exponent:
+        decw    EXP(%edi)
+
+LPseudoDenormal:
+        testb   $0xff,FPU_bits_lost     /* bits lost == underflow */
+        movl    TAG_Special,%edx
+        jz      L_deNormalised
+
+        /* There must be a masked underflow */
+        push    %eax
+        pushl   EX_Underflow
+        call    EXCEPTION
+        popl    %eax
+        popl    %eax
+        movl    TAG_Special,%edx
+        jmp     L_deNormalised
+
+
+/*
+ * The operations resulted in a number too small to represent.
+ * Masked response.
+ */
+L_underflow_to_zero:
+        push    %eax
+        call    set_precision_flag_down
+        popl    %eax
+
+        push    %eax
+        pushl   EX_Underflow
+        call    EXCEPTION
+        popl    %eax
+        popl    %eax
+
+/* Reduce the exponent to EXP_UNDER */
+        movw    EXP_UNDER,EXP(%edi)
+        movl    TAG_Zero,%edx
+        jmp     L_Store_significand
+
+
+/* The operations resulted in a number too large to represent. */
+L_overflow:
+        addw    EXTENDED_Ebias,EXP(%edi)        /* Set for unmasked response. */
+        push    %edi
+        call    arith_overflow
+        pop     %edi
+        jmp     fpu_reg_round_signed_special_exit
+
+
+Signal_underflow:
+        /* The number may have been changed to a non-denormal */
+        /* by the rounding operations. */
+        cmpw    EXP_UNDER,EXP(%edi)
+        jle     Do_unmasked_underflow
+
+        jmp     L_Normalised
+
+Do_unmasked_underflow:
+        /* Increase the exponent by the magic number */
+        addw    $(3*(1<<13)),EXP(%edi)
+        push    %eax
+        pushl   EX_Underflow
+        call    EXCEPTION
+        popl    %eax
+        popl    %eax
+        jmp     L_Normalised
+
+
+#ifdef PARANOID
+#ifdef PECULIAR_486
+L_bugged_denorm_486:
+        pushl   EX_INTERNAL|0x236
+        call    EXCEPTION
+        popl    %ebx
+        jmp     L_exception_exit
+#else
+L_bugged_denorm:
+        pushl   EX_INTERNAL|0x230
+        call    EXCEPTION
+        popl    %ebx
+        jmp     L_exception_exit
+#endif /* PECULIAR_486 */ 
+
+L_bugged_round24:
+        pushl   EX_INTERNAL|0x231
+        call    EXCEPTION
+        popl    %ebx
+        jmp     L_exception_exit
+
+L_bugged_round53:
+        pushl   EX_INTERNAL|0x232
+        call    EXCEPTION
+        popl    %ebx
+        jmp     L_exception_exit
+
+L_bugged_round64:
+        pushl   EX_INTERNAL|0x233
+        call    EXCEPTION
+        popl    %ebx
+        jmp     L_exception_exit
+
+L_norm_bugged:
+        pushl   EX_INTERNAL|0x234
+        call    EXCEPTION
+        popl    %ebx
+        jmp     L_exception_exit
+
+L_entry_bugged:
+        pushl   EX_INTERNAL|0x235
+        call    EXCEPTION
+        popl    %ebx
+L_exception_exit:
+        mov     $-1,%eax
+        jmp     fpu_reg_round_special_exit
+#endif /* PARANOID */