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1275 |
phoenix |
.file "reg_round.S"
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/*---------------------------------------------------------------------------+
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| reg_round.S |
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| Rounding/truncation/etc for FPU basic arithmetic functions. |
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| Copyright (C) 1993,1995,1997 |
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| W. Metzenthen, 22 Parker St, Ormond, Vic 3163, |
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| Australia. E-mail billm@suburbia.net |
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| |
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| This code has four possible entry points. |
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| The following must be entered by a jmp instruction: |
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| fpu_reg_round, fpu_reg_round_sqrt, and fpu_Arith_exit. |
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| |
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| The FPU_round entry point is intended to be used by C code. |
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| From C, call as: |
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| int FPU_round(FPU_REG *arg, unsigned int extent, unsigned int control_w) |
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| |
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| Return value is the tag of the answer, or-ed with FPU_Exception if |
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| one was raised, or -1 on internal error. |
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| |
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| For correct "up" and "down" rounding, the argument must have the correct |
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| sign. |
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| |
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+---------------------------------------------------------------------------*/
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/*---------------------------------------------------------------------------+
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| Four entry points. |
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| |
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| Needed by both the fpu_reg_round and fpu_reg_round_sqrt entry points: |
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| %eax:%ebx 64 bit significand |
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| %edx 32 bit extension of the significand |
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| %edi pointer to an FPU_REG for the result to be stored |
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| stack calling function must have set up a C stack frame and |
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| pushed %esi, %edi, and %ebx |
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| |
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| Needed just for the fpu_reg_round_sqrt entry point: |
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| %cx A control word in the same format as the FPU control word. |
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| Otherwise, PARAM4 must give such a value. |
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| The significand and its extension are assumed to be exact in the |
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| following sense: |
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| If the significand by itself is the exact result then the significand |
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| extension (%edx) must contain 0, otherwise the significand extension |
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| must be non-zero. |
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| If the significand extension is non-zero then the significand is |
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| smaller than the magnitude of the correct exact result by an amount |
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| greater than zero and less than one ls bit of the significand. |
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| The significand extension is only required to have three possible |
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| non-zero values: |
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| less than 0x80000000 <=> the significand is less than 1/2 an ls |
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| bit smaller than the magnitude of the |
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| true exact result. |
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| exactly 0x80000000 <=> the significand is exactly 1/2 an ls bit |
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| smaller than the magnitude of the true |
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| exact result. |
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| greater than 0x80000000 <=> the significand is more than 1/2 an ls |
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| bit smaller than the magnitude of the |
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| true exact result. |
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+---------------------------------------------------------------------------*/
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/*---------------------------------------------------------------------------+
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| The code in this module has become quite complex, but it should handle |
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| all of the FPU flags which are set at this stage of the basic arithmetic |
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| computations. |
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| There are a few rare cases where the results are not set identically to |
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| a real FPU. These require a bit more thought because at this stage the |
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| results of the code here appear to be more consistent... |
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| This may be changed in a future version. |
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+---------------------------------------------------------------------------*/
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#include "fpu_emu.h"
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#include "exception.h"
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#include "control_w.h"
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/* Flags for FPU_bits_lost */
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#define LOST_DOWN $1
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#define LOST_UP $2
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/* Flags for FPU_denormal */
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#define DENORMAL $1
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#define UNMASKED_UNDERFLOW $2
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#ifndef NON_REENTRANT_FPU
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/* Make the code re-entrant by putting
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local storage on the stack: */
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#define FPU_bits_lost (%esp)
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#define FPU_denormal 1(%esp)
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#else
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/* Not re-entrant, so we can gain speed by putting
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local storage in a static area: */
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.data
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.align 4,0
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FPU_bits_lost:
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.byte 0
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FPU_denormal:
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.byte 0
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#endif /* NON_REENTRANT_FPU */
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.text
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.globl fpu_reg_round
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.globl fpu_reg_round_sqrt
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.globl fpu_Arith_exit
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/* Entry point when called from C */
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ENTRY(FPU_round)
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pushl %ebp
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movl %esp,%ebp
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pushl %esi
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pushl %edi
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pushl %ebx
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movl PARAM1,%edi
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movl SIGH(%edi),%eax
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movl SIGL(%edi),%ebx
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movl PARAM2,%edx
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fpu_reg_round: /* Normal entry point */
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movl PARAM4,%ecx
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#ifndef NON_REENTRANT_FPU
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pushl %ebx /* adjust the stack pointer */
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#endif /* NON_REENTRANT_FPU */
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#ifdef PARANOID
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/* Cannot use this here yet */
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/* orl %eax,%eax */
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/* jns L_entry_bugged */
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#endif /* PARANOID */
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cmpw EXP_UNDER,EXP(%edi)
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jle L_Make_denorm /* The number is a de-normal */
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| 140 |
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movb $0,FPU_denormal /* 0 -> not a de-normal */
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| 142 |
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Denorm_done:
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movb $0,FPU_bits_lost /* No bits yet lost in rounding */
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| 145 |
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movl %ecx,%esi
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andl CW_PC,%ecx
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cmpl PR_64_BITS,%ecx
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je LRound_To_64
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cmpl PR_53_BITS,%ecx
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je LRound_To_53
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cmpl PR_24_BITS,%ecx
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je LRound_To_24
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#ifdef PECULIAR_486
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/* With the precision control bits set to 01 "(reserved)", a real 80486
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behaves as if the precision control bits were set to 11 "64 bits" */
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cmpl PR_RESERVED_BITS,%ecx
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je LRound_To_64
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#ifdef PARANOID
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jmp L_bugged_denorm_486
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#endif /* PARANOID */
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#else
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#ifdef PARANOID
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jmp L_bugged_denorm /* There is no bug, just a bad control word */
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#endif /* PARANOID */
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#endif /* PECULIAR_486 */
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| 170 |
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/* Round etc to 24 bit precision */
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LRound_To_24:
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movl %esi,%ecx
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andl CW_RC,%ecx
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cmpl RC_RND,%ecx
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je LRound_nearest_24
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cmpl RC_CHOP,%ecx
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je LCheck_truncate_24
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cmpl RC_UP,%ecx /* Towards +infinity */
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je LUp_24
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cmpl RC_DOWN,%ecx /* Towards -infinity */
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je LDown_24
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#ifdef PARANOID
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jmp L_bugged_round24
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#endif /* PARANOID */
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LUp_24:
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cmpb SIGN_POS,PARAM5
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jne LCheck_truncate_24 /* If negative then up==truncate */
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jmp LCheck_24_round_up
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LDown_24:
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cmpb SIGN_POS,PARAM5
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je LCheck_truncate_24 /* If positive then down==truncate */
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LCheck_24_round_up:
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movl %eax,%ecx
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andl $0x000000ff,%ecx
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orl %ebx,%ecx
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orl %edx,%ecx
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jnz LDo_24_round_up
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jmp L_Re_normalise
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LRound_nearest_24:
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/* Do rounding of the 24th bit if needed (nearest or even) */
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movl %eax,%ecx
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andl $0x000000ff,%ecx
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cmpl $0x00000080,%ecx
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jc LCheck_truncate_24 /* less than half, no increment needed */
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jne LGreater_Half_24 /* greater than half, increment needed */
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/* Possibly half, we need to check the ls bits */
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orl %ebx,%ebx
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jnz LGreater_Half_24 /* greater than half, increment needed */
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orl %edx,%edx
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jnz LGreater_Half_24 /* greater than half, increment needed */
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/* Exactly half, increment only if 24th bit is 1 (round to even) */
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testl $0x00000100,%eax
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jz LDo_truncate_24
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LGreater_Half_24: /* Rounding: increment at the 24th bit */
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LDo_24_round_up:
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andl $0xffffff00,%eax /* Truncate to 24 bits */
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xorl %ebx,%ebx
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movb LOST_UP,FPU_bits_lost
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addl $0x00000100,%eax
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jmp LCheck_Round_Overflow
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LCheck_truncate_24:
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movl %eax,%ecx
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andl $0x000000ff,%ecx
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orl %ebx,%ecx
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orl %edx,%ecx
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| 242 |
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jz L_Re_normalise /* No truncation needed */
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LDo_truncate_24:
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andl $0xffffff00,%eax /* Truncate to 24 bits */
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xorl %ebx,%ebx
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movb LOST_DOWN,FPU_bits_lost
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| 248 |
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jmp L_Re_normalise
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| 250 |
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/* Round etc to 53 bit precision */
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LRound_To_53:
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movl %esi,%ecx
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andl CW_RC,%ecx
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cmpl RC_RND,%ecx
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je LRound_nearest_53
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| 258 |
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cmpl RC_CHOP,%ecx
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| 259 |
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je LCheck_truncate_53
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| 261 |
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cmpl RC_UP,%ecx /* Towards +infinity */
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| 262 |
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je LUp_53
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| 263 |
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| 264 |
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cmpl RC_DOWN,%ecx /* Towards -infinity */
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| 265 |
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je LDown_53
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| 266 |
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| 267 |
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#ifdef PARANOID
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| 268 |
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jmp L_bugged_round53
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| 269 |
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#endif /* PARANOID */
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| 270 |
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| 271 |
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LUp_53:
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| 272 |
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cmpb SIGN_POS,PARAM5
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jne LCheck_truncate_53 /* If negative then up==truncate */
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| 275 |
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jmp LCheck_53_round_up
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| 276 |
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| 277 |
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LDown_53:
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cmpb SIGN_POS,PARAM5
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je LCheck_truncate_53 /* If positive then down==truncate */
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| 280 |
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| 281 |
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LCheck_53_round_up:
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| 282 |
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movl %ebx,%ecx
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| 283 |
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andl $0x000007ff,%ecx
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| 284 |
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orl %edx,%ecx
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| 285 |
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jnz LDo_53_round_up
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| 286 |
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jmp L_Re_normalise
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| 287 |
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| 288 |
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LRound_nearest_53:
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| 289 |
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/* Do rounding of the 53rd bit if needed (nearest or even) */
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| 290 |
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movl %ebx,%ecx
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| 291 |
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andl $0x000007ff,%ecx
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| 292 |
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cmpl $0x00000400,%ecx
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| 293 |
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jc LCheck_truncate_53 /* less than half, no increment needed */
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| 294 |
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| 295 |
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jnz LGreater_Half_53 /* greater than half, increment needed */
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| 296 |
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| 297 |
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/* Possibly half, we need to check the ls bits */
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| 298 |
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orl %edx,%edx
|
| 299 |
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jnz LGreater_Half_53 /* greater than half, increment needed */
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| 300 |
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| 301 |
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/* Exactly half, increment only if 53rd bit is 1 (round to even) */
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| 302 |
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testl $0x00000800,%ebx
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| 303 |
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jz LTruncate_53
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| 304 |
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|
| 305 |
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LGreater_Half_53: /* Rounding: increment at the 53rd bit */
|
| 306 |
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LDo_53_round_up:
|
| 307 |
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movb LOST_UP,FPU_bits_lost
|
| 308 |
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andl $0xfffff800,%ebx /* Truncate to 53 bits */
|
| 309 |
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addl $0x00000800,%ebx
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| 310 |
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adcl $0,%eax
|
| 311 |
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jmp LCheck_Round_Overflow
|
| 312 |
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|
| 313 |
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LCheck_truncate_53:
|
| 314 |
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movl %ebx,%ecx
|
| 315 |
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andl $0x000007ff,%ecx
|
| 316 |
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orl %edx,%ecx
|
| 317 |
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jz L_Re_normalise
|
| 318 |
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|
| 319 |
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LTruncate_53:
|
| 320 |
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movb LOST_DOWN,FPU_bits_lost
|
| 321 |
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andl $0xfffff800,%ebx /* Truncate to 53 bits */
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| 322 |
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jmp L_Re_normalise
|
| 323 |
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|
| 324 |
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| 325 |
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/* Round etc to 64 bit precision */
|
| 326 |
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LRound_To_64:
|
| 327 |
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movl %esi,%ecx
|
| 328 |
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andl CW_RC,%ecx
|
| 329 |
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cmpl RC_RND,%ecx
|
| 330 |
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je LRound_nearest_64
|
| 331 |
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|
| 332 |
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cmpl RC_CHOP,%ecx
|
| 333 |
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je LCheck_truncate_64
|
| 334 |
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|
| 335 |
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cmpl RC_UP,%ecx /* Towards +infinity */
|
| 336 |
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je LUp_64
|
| 337 |
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|
|
| 338 |
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cmpl RC_DOWN,%ecx /* Towards -infinity */
|
| 339 |
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je LDown_64
|
| 340 |
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|
| 341 |
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#ifdef PARANOID
|
| 342 |
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jmp L_bugged_round64
|
| 343 |
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#endif /* PARANOID */
|
| 344 |
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|
| 345 |
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LUp_64:
|
| 346 |
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cmpb SIGN_POS,PARAM5
|
| 347 |
|
|
jne LCheck_truncate_64 /* If negative then up==truncate */
|
| 348 |
|
|
|
| 349 |
|
|
orl %edx,%edx
|
| 350 |
|
|
jnz LDo_64_round_up
|
| 351 |
|
|
jmp L_Re_normalise
|
| 352 |
|
|
|
| 353 |
|
|
LDown_64:
|
| 354 |
|
|
cmpb SIGN_POS,PARAM5
|
| 355 |
|
|
je LCheck_truncate_64 /* If positive then down==truncate */
|
| 356 |
|
|
|
| 357 |
|
|
orl %edx,%edx
|
| 358 |
|
|
jnz LDo_64_round_up
|
| 359 |
|
|
jmp L_Re_normalise
|
| 360 |
|
|
|
| 361 |
|
|
LRound_nearest_64:
|
| 362 |
|
|
cmpl $0x80000000,%edx
|
| 363 |
|
|
jc LCheck_truncate_64
|
| 364 |
|
|
|
| 365 |
|
|
jne LDo_64_round_up
|
| 366 |
|
|
|
| 367 |
|
|
/* Now test for round-to-even */
|
| 368 |
|
|
testb $1,%bl
|
| 369 |
|
|
jz LCheck_truncate_64
|
| 370 |
|
|
|
| 371 |
|
|
LDo_64_round_up:
|
| 372 |
|
|
movb LOST_UP,FPU_bits_lost
|
| 373 |
|
|
addl $1,%ebx
|
| 374 |
|
|
adcl $0,%eax
|
| 375 |
|
|
|
| 376 |
|
|
LCheck_Round_Overflow:
|
| 377 |
|
|
jnc L_Re_normalise
|
| 378 |
|
|
|
| 379 |
|
|
/* Overflow, adjust the result (significand to 1.0) */
|
| 380 |
|
|
rcrl $1,%eax
|
| 381 |
|
|
rcrl $1,%ebx
|
| 382 |
|
|
incw EXP(%edi)
|
| 383 |
|
|
jmp L_Re_normalise
|
| 384 |
|
|
|
| 385 |
|
|
LCheck_truncate_64:
|
| 386 |
|
|
orl %edx,%edx
|
| 387 |
|
|
jz L_Re_normalise
|
| 388 |
|
|
|
| 389 |
|
|
LTruncate_64:
|
| 390 |
|
|
movb LOST_DOWN,FPU_bits_lost
|
| 391 |
|
|
|
| 392 |
|
|
L_Re_normalise:
|
| 393 |
|
|
testb $0xff,FPU_denormal
|
| 394 |
|
|
jnz Normalise_result
|
| 395 |
|
|
|
| 396 |
|
|
L_Normalised:
|
| 397 |
|
|
movl TAG_Valid,%edx
|
| 398 |
|
|
|
| 399 |
|
|
L_deNormalised:
|
| 400 |
|
|
cmpb LOST_UP,FPU_bits_lost
|
| 401 |
|
|
je L_precision_lost_up
|
| 402 |
|
|
|
| 403 |
|
|
cmpb LOST_DOWN,FPU_bits_lost
|
| 404 |
|
|
je L_precision_lost_down
|
| 405 |
|
|
|
| 406 |
|
|
L_no_precision_loss:
|
| 407 |
|
|
/* store the result */
|
| 408 |
|
|
|
| 409 |
|
|
L_Store_significand:
|
| 410 |
|
|
movl %eax,SIGH(%edi)
|
| 411 |
|
|
movl %ebx,SIGL(%edi)
|
| 412 |
|
|
|
| 413 |
|
|
cmpw EXP_OVER,EXP(%edi)
|
| 414 |
|
|
jge L_overflow
|
| 415 |
|
|
|
| 416 |
|
|
movl %edx,%eax
|
| 417 |
|
|
|
| 418 |
|
|
/* Convert the exponent to 80x87 form. */
|
| 419 |
|
|
addw EXTENDED_Ebias,EXP(%edi)
|
| 420 |
|
|
andw $0x7fff,EXP(%edi)
|
| 421 |
|
|
|
| 422 |
|
|
fpu_reg_round_signed_special_exit:
|
| 423 |
|
|
|
| 424 |
|
|
cmpb SIGN_POS,PARAM5
|
| 425 |
|
|
je fpu_reg_round_special_exit
|
| 426 |
|
|
|
| 427 |
|
|
orw $0x8000,EXP(%edi) /* Negative sign for the result. */
|
| 428 |
|
|
|
| 429 |
|
|
fpu_reg_round_special_exit:
|
| 430 |
|
|
|
| 431 |
|
|
#ifndef NON_REENTRANT_FPU
|
| 432 |
|
|
popl %ebx /* adjust the stack pointer */
|
| 433 |
|
|
#endif /* NON_REENTRANT_FPU */
|
| 434 |
|
|
|
| 435 |
|
|
fpu_Arith_exit:
|
| 436 |
|
|
popl %ebx
|
| 437 |
|
|
popl %edi
|
| 438 |
|
|
popl %esi
|
| 439 |
|
|
leave
|
| 440 |
|
|
ret
|
| 441 |
|
|
|
| 442 |
|
|
|
| 443 |
|
|
/*
|
| 444 |
|
|
* Set the FPU status flags to represent precision loss due to
|
| 445 |
|
|
* round-up.
|
| 446 |
|
|
*/
|
| 447 |
|
|
L_precision_lost_up:
|
| 448 |
|
|
push %edx
|
| 449 |
|
|
push %eax
|
| 450 |
|
|
call SYMBOL_NAME(set_precision_flag_up)
|
| 451 |
|
|
popl %eax
|
| 452 |
|
|
popl %edx
|
| 453 |
|
|
jmp L_no_precision_loss
|
| 454 |
|
|
|
| 455 |
|
|
/*
|
| 456 |
|
|
* Set the FPU status flags to represent precision loss due to
|
| 457 |
|
|
* truncation.
|
| 458 |
|
|
*/
|
| 459 |
|
|
L_precision_lost_down:
|
| 460 |
|
|
push %edx
|
| 461 |
|
|
push %eax
|
| 462 |
|
|
call SYMBOL_NAME(set_precision_flag_down)
|
| 463 |
|
|
popl %eax
|
| 464 |
|
|
popl %edx
|
| 465 |
|
|
jmp L_no_precision_loss
|
| 466 |
|
|
|
| 467 |
|
|
|
| 468 |
|
|
/*
|
| 469 |
|
|
* The number is a denormal (which might get rounded up to a normal)
|
| 470 |
|
|
* Shift the number right the required number of bits, which will
|
| 471 |
|
|
* have to be undone later...
|
| 472 |
|
|
*/
|
| 473 |
|
|
L_Make_denorm:
|
| 474 |
|
|
/* The action to be taken depends upon whether the underflow
|
| 475 |
|
|
exception is masked */
|
| 476 |
|
|
testb CW_Underflow,%cl /* Underflow mask. */
|
| 477 |
|
|
jz Unmasked_underflow /* Do not make a denormal. */
|
| 478 |
|
|
|
| 479 |
|
|
movb DENORMAL,FPU_denormal
|
| 480 |
|
|
|
| 481 |
|
|
pushl %ecx /* Save */
|
| 482 |
|
|
movw EXP_UNDER+1,%cx
|
| 483 |
|
|
subw EXP(%edi),%cx
|
| 484 |
|
|
|
| 485 |
|
|
cmpw $64,%cx /* shrd only works for 0..31 bits */
|
| 486 |
|
|
jnc Denorm_shift_more_than_63
|
| 487 |
|
|
|
| 488 |
|
|
cmpw $32,%cx /* shrd only works for 0..31 bits */
|
| 489 |
|
|
jnc Denorm_shift_more_than_32
|
| 490 |
|
|
|
| 491 |
|
|
/*
|
| 492 |
|
|
* We got here without jumps by assuming that the most common requirement
|
| 493 |
|
|
* is for a small de-normalising shift.
|
| 494 |
|
|
* Shift by [1..31] bits
|
| 495 |
|
|
*/
|
| 496 |
|
|
addw %cx,EXP(%edi)
|
| 497 |
|
|
orl %edx,%edx /* extension */
|
| 498 |
|
|
setne %ch /* Save whether %edx is non-zero */
|
| 499 |
|
|
xorl %edx,%edx
|
| 500 |
|
|
shrd %cl,%ebx,%edx
|
| 501 |
|
|
shrd %cl,%eax,%ebx
|
| 502 |
|
|
shr %cl,%eax
|
| 503 |
|
|
orb %ch,%dl
|
| 504 |
|
|
popl %ecx
|
| 505 |
|
|
jmp Denorm_done
|
| 506 |
|
|
|
| 507 |
|
|
/* Shift by [32..63] bits */
|
| 508 |
|
|
Denorm_shift_more_than_32:
|
| 509 |
|
|
addw %cx,EXP(%edi)
|
| 510 |
|
|
subb $32,%cl
|
| 511 |
|
|
orl %edx,%edx
|
| 512 |
|
|
setne %ch
|
| 513 |
|
|
orb %ch,%bl
|
| 514 |
|
|
xorl %edx,%edx
|
| 515 |
|
|
shrd %cl,%ebx,%edx
|
| 516 |
|
|
shrd %cl,%eax,%ebx
|
| 517 |
|
|
shr %cl,%eax
|
| 518 |
|
|
orl %edx,%edx /* test these 32 bits */
|
| 519 |
|
|
setne %cl
|
| 520 |
|
|
orb %ch,%bl
|
| 521 |
|
|
orb %cl,%bl
|
| 522 |
|
|
movl %ebx,%edx
|
| 523 |
|
|
movl %eax,%ebx
|
| 524 |
|
|
xorl %eax,%eax
|
| 525 |
|
|
popl %ecx
|
| 526 |
|
|
jmp Denorm_done
|
| 527 |
|
|
|
| 528 |
|
|
/* Shift by [64..) bits */
|
| 529 |
|
|
Denorm_shift_more_than_63:
|
| 530 |
|
|
cmpw $64,%cx
|
| 531 |
|
|
jne Denorm_shift_more_than_64
|
| 532 |
|
|
|
| 533 |
|
|
/* Exactly 64 bit shift */
|
| 534 |
|
|
addw %cx,EXP(%edi)
|
| 535 |
|
|
xorl %ecx,%ecx
|
| 536 |
|
|
orl %edx,%edx
|
| 537 |
|
|
setne %cl
|
| 538 |
|
|
orl %ebx,%ebx
|
| 539 |
|
|
setne %ch
|
| 540 |
|
|
orb %ch,%cl
|
| 541 |
|
|
orb %cl,%al
|
| 542 |
|
|
movl %eax,%edx
|
| 543 |
|
|
xorl %eax,%eax
|
| 544 |
|
|
xorl %ebx,%ebx
|
| 545 |
|
|
popl %ecx
|
| 546 |
|
|
jmp Denorm_done
|
| 547 |
|
|
|
| 548 |
|
|
Denorm_shift_more_than_64:
|
| 549 |
|
|
movw EXP_UNDER+1,EXP(%edi)
|
| 550 |
|
|
/* This is easy, %eax must be non-zero, so.. */
|
| 551 |
|
|
movl $1,%edx
|
| 552 |
|
|
xorl %eax,%eax
|
| 553 |
|
|
xorl %ebx,%ebx
|
| 554 |
|
|
popl %ecx
|
| 555 |
|
|
jmp Denorm_done
|
| 556 |
|
|
|
| 557 |
|
|
|
| 558 |
|
|
Unmasked_underflow:
|
| 559 |
|
|
movb UNMASKED_UNDERFLOW,FPU_denormal
|
| 560 |
|
|
jmp Denorm_done
|
| 561 |
|
|
|
| 562 |
|
|
|
| 563 |
|
|
/* Undo the de-normalisation. */
|
| 564 |
|
|
Normalise_result:
|
| 565 |
|
|
cmpb UNMASKED_UNDERFLOW,FPU_denormal
|
| 566 |
|
|
je Signal_underflow
|
| 567 |
|
|
|
| 568 |
|
|
/* The number must be a denormal if we got here. */
|
| 569 |
|
|
#ifdef PARANOID
|
| 570 |
|
|
/* But check it... just in case. */
|
| 571 |
|
|
cmpw EXP_UNDER+1,EXP(%edi)
|
| 572 |
|
|
jne L_norm_bugged
|
| 573 |
|
|
#endif /* PARANOID */
|
| 574 |
|
|
|
| 575 |
|
|
#ifdef PECULIAR_486
|
| 576 |
|
|
/*
|
| 577 |
|
|
* This implements a special feature of 80486 behaviour.
|
| 578 |
|
|
* Underflow will be signalled even if the number is
|
| 579 |
|
|
* not a denormal after rounding.
|
| 580 |
|
|
* This difference occurs only for masked underflow, and not
|
| 581 |
|
|
* in the unmasked case.
|
| 582 |
|
|
* Actual 80486 behaviour differs from this in some circumstances.
|
| 583 |
|
|
*/
|
| 584 |
|
|
orl %eax,%eax /* ms bits */
|
| 585 |
|
|
js LPseudoDenormal /* Will be masked underflow */
|
| 586 |
|
|
#else
|
| 587 |
|
|
orl %eax,%eax /* ms bits */
|
| 588 |
|
|
js L_Normalised /* No longer a denormal */
|
| 589 |
|
|
#endif /* PECULIAR_486 */
|
| 590 |
|
|
|
| 591 |
|
|
jnz LDenormal_adj_exponent
|
| 592 |
|
|
|
| 593 |
|
|
orl %ebx,%ebx
|
| 594 |
|
|
jz L_underflow_to_zero /* The contents are zero */
|
| 595 |
|
|
|
| 596 |
|
|
LDenormal_adj_exponent:
|
| 597 |
|
|
decw EXP(%edi)
|
| 598 |
|
|
|
| 599 |
|
|
LPseudoDenormal:
|
| 600 |
|
|
testb $0xff,FPU_bits_lost /* bits lost == underflow */
|
| 601 |
|
|
movl TAG_Special,%edx
|
| 602 |
|
|
jz L_deNormalised
|
| 603 |
|
|
|
| 604 |
|
|
/* There must be a masked underflow */
|
| 605 |
|
|
push %eax
|
| 606 |
|
|
pushl EX_Underflow
|
| 607 |
|
|
call EXCEPTION
|
| 608 |
|
|
popl %eax
|
| 609 |
|
|
popl %eax
|
| 610 |
|
|
movl TAG_Special,%edx
|
| 611 |
|
|
jmp L_deNormalised
|
| 612 |
|
|
|
| 613 |
|
|
|
| 614 |
|
|
/*
|
| 615 |
|
|
* The operations resulted in a number too small to represent.
|
| 616 |
|
|
* Masked response.
|
| 617 |
|
|
*/
|
| 618 |
|
|
L_underflow_to_zero:
|
| 619 |
|
|
push %eax
|
| 620 |
|
|
call SYMBOL_NAME(set_precision_flag_down)
|
| 621 |
|
|
popl %eax
|
| 622 |
|
|
|
| 623 |
|
|
push %eax
|
| 624 |
|
|
pushl EX_Underflow
|
| 625 |
|
|
call EXCEPTION
|
| 626 |
|
|
popl %eax
|
| 627 |
|
|
popl %eax
|
| 628 |
|
|
|
| 629 |
|
|
/* Reduce the exponent to EXP_UNDER */
|
| 630 |
|
|
movw EXP_UNDER,EXP(%edi)
|
| 631 |
|
|
movl TAG_Zero,%edx
|
| 632 |
|
|
jmp L_Store_significand
|
| 633 |
|
|
|
| 634 |
|
|
|
| 635 |
|
|
/* The operations resulted in a number too large to represent. */
|
| 636 |
|
|
L_overflow:
|
| 637 |
|
|
addw EXTENDED_Ebias,EXP(%edi) /* Set for unmasked response. */
|
| 638 |
|
|
push %edi
|
| 639 |
|
|
call SYMBOL_NAME(arith_overflow)
|
| 640 |
|
|
pop %edi
|
| 641 |
|
|
jmp fpu_reg_round_signed_special_exit
|
| 642 |
|
|
|
| 643 |
|
|
|
| 644 |
|
|
Signal_underflow:
|
| 645 |
|
|
/* The number may have been changed to a non-denormal */
|
| 646 |
|
|
/* by the rounding operations. */
|
| 647 |
|
|
cmpw EXP_UNDER,EXP(%edi)
|
| 648 |
|
|
jle Do_unmasked_underflow
|
| 649 |
|
|
|
| 650 |
|
|
jmp L_Normalised
|
| 651 |
|
|
|
| 652 |
|
|
Do_unmasked_underflow:
|
| 653 |
|
|
/* Increase the exponent by the magic number */
|
| 654 |
|
|
addw $(3*(1<<13)),EXP(%edi)
|
| 655 |
|
|
push %eax
|
| 656 |
|
|
pushl EX_Underflow
|
| 657 |
|
|
call EXCEPTION
|
| 658 |
|
|
popl %eax
|
| 659 |
|
|
popl %eax
|
| 660 |
|
|
jmp L_Normalised
|
| 661 |
|
|
|
| 662 |
|
|
|
| 663 |
|
|
#ifdef PARANOID
|
| 664 |
|
|
#ifdef PECULIAR_486
|
| 665 |
|
|
L_bugged_denorm_486:
|
| 666 |
|
|
pushl EX_INTERNAL|0x236
|
| 667 |
|
|
call EXCEPTION
|
| 668 |
|
|
popl %ebx
|
| 669 |
|
|
jmp L_exception_exit
|
| 670 |
|
|
#else
|
| 671 |
|
|
L_bugged_denorm:
|
| 672 |
|
|
pushl EX_INTERNAL|0x230
|
| 673 |
|
|
call EXCEPTION
|
| 674 |
|
|
popl %ebx
|
| 675 |
|
|
jmp L_exception_exit
|
| 676 |
|
|
#endif /* PECULIAR_486 */
|
| 677 |
|
|
|
| 678 |
|
|
L_bugged_round24:
|
| 679 |
|
|
pushl EX_INTERNAL|0x231
|
| 680 |
|
|
call EXCEPTION
|
| 681 |
|
|
popl %ebx
|
| 682 |
|
|
jmp L_exception_exit
|
| 683 |
|
|
|
| 684 |
|
|
L_bugged_round53:
|
| 685 |
|
|
pushl EX_INTERNAL|0x232
|
| 686 |
|
|
call EXCEPTION
|
| 687 |
|
|
popl %ebx
|
| 688 |
|
|
jmp L_exception_exit
|
| 689 |
|
|
|
| 690 |
|
|
L_bugged_round64:
|
| 691 |
|
|
pushl EX_INTERNAL|0x233
|
| 692 |
|
|
call EXCEPTION
|
| 693 |
|
|
popl %ebx
|
| 694 |
|
|
jmp L_exception_exit
|
| 695 |
|
|
|
| 696 |
|
|
L_norm_bugged:
|
| 697 |
|
|
pushl EX_INTERNAL|0x234
|
| 698 |
|
|
call EXCEPTION
|
| 699 |
|
|
popl %ebx
|
| 700 |
|
|
jmp L_exception_exit
|
| 701 |
|
|
|
| 702 |
|
|
L_entry_bugged:
|
| 703 |
|
|
pushl EX_INTERNAL|0x235
|
| 704 |
|
|
call EXCEPTION
|
| 705 |
|
|
popl %ebx
|
| 706 |
|
|
L_exception_exit:
|
| 707 |
|
|
mov $-1,%eax
|
| 708 |
|
|
jmp fpu_reg_round_special_exit
|
| 709 |
|
|
#endif /* PARANOID */
|
