mirror of
https://github.com/edk2-porting/linux-next.git
synced 2024-12-27 14:43:58 +08:00
da957e111b
Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Ingo Molnar <mingo@elte.hu>
472 lines
12 KiB
ArmAsm
472 lines
12 KiB
ArmAsm
.file "reg_u_div.S"
|
|
/*---------------------------------------------------------------------------+
|
|
| reg_u_div.S |
|
|
| |
|
|
| Divide one FPU_REG by another and put the result in a destination FPU_REG.|
|
|
| |
|
|
| Copyright (C) 1992,1993,1995,1997 |
|
|
| W. Metzenthen, 22 Parker St, Ormond, Vic 3163, Australia |
|
|
| E-mail billm@suburbia.net |
|
|
| |
|
|
| |
|
|
+---------------------------------------------------------------------------*/
|
|
|
|
/*---------------------------------------------------------------------------+
|
|
| Call from C as: |
|
|
| int FPU_u_div(FPU_REG *a, FPU_REG *b, FPU_REG *dest, |
|
|
| unsigned int control_word, char *sign) |
|
|
| |
|
|
| Does not compute the destination exponent, but does adjust it. |
|
|
| |
|
|
| Return value is the tag of the answer, or-ed with FPU_Exception if |
|
|
| one was raised, or -1 on internal error. |
|
|
+---------------------------------------------------------------------------*/
|
|
|
|
#include "exception.h"
|
|
#include "fpu_emu.h"
|
|
#include "control_w.h"
|
|
|
|
|
|
/* #define dSIGL(x) (x) */
|
|
/* #define dSIGH(x) 4(x) */
|
|
|
|
|
|
#ifndef NON_REENTRANT_FPU
|
|
/*
|
|
Local storage on the stack:
|
|
Result: FPU_accum_3:FPU_accum_2:FPU_accum_1:FPU_accum_0
|
|
Overflow flag: ovfl_flag
|
|
*/
|
|
#define FPU_accum_3 -4(%ebp)
|
|
#define FPU_accum_2 -8(%ebp)
|
|
#define FPU_accum_1 -12(%ebp)
|
|
#define FPU_accum_0 -16(%ebp)
|
|
#define FPU_result_1 -20(%ebp)
|
|
#define FPU_result_2 -24(%ebp)
|
|
#define FPU_ovfl_flag -28(%ebp)
|
|
|
|
#else
|
|
.data
|
|
/*
|
|
Local storage in a static area:
|
|
Result: FPU_accum_3:FPU_accum_2:FPU_accum_1:FPU_accum_0
|
|
Overflow flag: ovfl_flag
|
|
*/
|
|
.align 4,0
|
|
FPU_accum_3:
|
|
.long 0
|
|
FPU_accum_2:
|
|
.long 0
|
|
FPU_accum_1:
|
|
.long 0
|
|
FPU_accum_0:
|
|
.long 0
|
|
FPU_result_1:
|
|
.long 0
|
|
FPU_result_2:
|
|
.long 0
|
|
FPU_ovfl_flag:
|
|
.byte 0
|
|
#endif /* NON_REENTRANT_FPU */
|
|
|
|
#define REGA PARAM1
|
|
#define REGB PARAM2
|
|
#define DEST PARAM3
|
|
|
|
.text
|
|
ENTRY(FPU_u_div)
|
|
pushl %ebp
|
|
movl %esp,%ebp
|
|
#ifndef NON_REENTRANT_FPU
|
|
subl $28,%esp
|
|
#endif /* NON_REENTRANT_FPU */
|
|
|
|
pushl %esi
|
|
pushl %edi
|
|
pushl %ebx
|
|
|
|
movl REGA,%esi
|
|
movl REGB,%ebx
|
|
movl DEST,%edi
|
|
|
|
movswl EXP(%esi),%edx
|
|
movswl EXP(%ebx),%eax
|
|
subl %eax,%edx
|
|
addl EXP_BIAS,%edx
|
|
|
|
/* A denormal and a large number can cause an exponent underflow */
|
|
cmpl EXP_WAY_UNDER,%edx
|
|
jg xExp_not_underflow
|
|
|
|
/* Set to a really low value allow correct handling */
|
|
movl EXP_WAY_UNDER,%edx
|
|
|
|
xExp_not_underflow:
|
|
|
|
movw %dx,EXP(%edi)
|
|
|
|
#ifdef PARANOID
|
|
/* testl $0x80000000, SIGH(%esi) // Dividend */
|
|
/* je L_bugged */
|
|
testl $0x80000000, SIGH(%ebx) /* Divisor */
|
|
je L_bugged
|
|
#endif /* PARANOID */
|
|
|
|
/* Check if the divisor can be treated as having just 32 bits */
|
|
cmpl $0,SIGL(%ebx)
|
|
jnz L_Full_Division /* Can't do a quick divide */
|
|
|
|
/* We should be able to zip through the division here */
|
|
movl SIGH(%ebx),%ecx /* The divisor */
|
|
movl SIGH(%esi),%edx /* Dividend */
|
|
movl SIGL(%esi),%eax /* Dividend */
|
|
|
|
cmpl %ecx,%edx
|
|
setaeb FPU_ovfl_flag /* Keep a record */
|
|
jb L_no_adjust
|
|
|
|
subl %ecx,%edx /* Prevent the overflow */
|
|
|
|
L_no_adjust:
|
|
/* Divide the 64 bit number by the 32 bit denominator */
|
|
divl %ecx
|
|
movl %eax,FPU_result_2
|
|
|
|
/* Work on the remainder of the first division */
|
|
xorl %eax,%eax
|
|
divl %ecx
|
|
movl %eax,FPU_result_1
|
|
|
|
/* Work on the remainder of the 64 bit division */
|
|
xorl %eax,%eax
|
|
divl %ecx
|
|
|
|
testb $255,FPU_ovfl_flag /* was the num > denom ? */
|
|
je L_no_overflow
|
|
|
|
/* Do the shifting here */
|
|
/* increase the exponent */
|
|
incw EXP(%edi)
|
|
|
|
/* shift the mantissa right one bit */
|
|
stc /* To set the ms bit */
|
|
rcrl FPU_result_2
|
|
rcrl FPU_result_1
|
|
rcrl %eax
|
|
|
|
L_no_overflow:
|
|
jmp LRound_precision /* Do the rounding as required */
|
|
|
|
|
|
/*---------------------------------------------------------------------------+
|
|
| Divide: Return arg1/arg2 to arg3. |
|
|
| |
|
|
| This routine does not use the exponents of arg1 and arg2, but does |
|
|
| adjust the exponent of arg3. |
|
|
| |
|
|
| The maximum returned value is (ignoring exponents) |
|
|
| .ffffffff ffffffff |
|
|
| ------------------ = 1.ffffffff fffffffe |
|
|
| .80000000 00000000 |
|
|
| and the minimum is |
|
|
| .80000000 00000000 |
|
|
| ------------------ = .80000000 00000001 (rounded) |
|
|
| .ffffffff ffffffff |
|
|
| |
|
|
+---------------------------------------------------------------------------*/
|
|
|
|
|
|
L_Full_Division:
|
|
/* Save extended dividend in local register */
|
|
movl SIGL(%esi),%eax
|
|
movl %eax,FPU_accum_2
|
|
movl SIGH(%esi),%eax
|
|
movl %eax,FPU_accum_3
|
|
xorl %eax,%eax
|
|
movl %eax,FPU_accum_1 /* zero the extension */
|
|
movl %eax,FPU_accum_0 /* zero the extension */
|
|
|
|
movl SIGL(%esi),%eax /* Get the current num */
|
|
movl SIGH(%esi),%edx
|
|
|
|
/*----------------------------------------------------------------------*/
|
|
/* Initialization done.
|
|
Do the first 32 bits. */
|
|
|
|
movb $0,FPU_ovfl_flag
|
|
cmpl SIGH(%ebx),%edx /* Test for imminent overflow */
|
|
jb LLess_than_1
|
|
ja LGreater_than_1
|
|
|
|
cmpl SIGL(%ebx),%eax
|
|
jb LLess_than_1
|
|
|
|
LGreater_than_1:
|
|
/* The dividend is greater or equal, would cause overflow */
|
|
setaeb FPU_ovfl_flag /* Keep a record */
|
|
|
|
subl SIGL(%ebx),%eax
|
|
sbbl SIGH(%ebx),%edx /* Prevent the overflow */
|
|
movl %eax,FPU_accum_2
|
|
movl %edx,FPU_accum_3
|
|
|
|
LLess_than_1:
|
|
/* At this point, we have a dividend < divisor, with a record of
|
|
adjustment in FPU_ovfl_flag */
|
|
|
|
/* We will divide by a number which is too large */
|
|
movl SIGH(%ebx),%ecx
|
|
addl $1,%ecx
|
|
jnc LFirst_div_not_1
|
|
|
|
/* here we need to divide by 100000000h,
|
|
i.e., no division at all.. */
|
|
mov %edx,%eax
|
|
jmp LFirst_div_done
|
|
|
|
LFirst_div_not_1:
|
|
divl %ecx /* Divide the numerator by the augmented
|
|
denom ms dw */
|
|
|
|
LFirst_div_done:
|
|
movl %eax,FPU_result_2 /* Put the result in the answer */
|
|
|
|
mull SIGH(%ebx) /* mul by the ms dw of the denom */
|
|
|
|
subl %eax,FPU_accum_2 /* Subtract from the num local reg */
|
|
sbbl %edx,FPU_accum_3
|
|
|
|
movl FPU_result_2,%eax /* Get the result back */
|
|
mull SIGL(%ebx) /* now mul the ls dw of the denom */
|
|
|
|
subl %eax,FPU_accum_1 /* Subtract from the num local reg */
|
|
sbbl %edx,FPU_accum_2
|
|
sbbl $0,FPU_accum_3
|
|
je LDo_2nd_32_bits /* Must check for non-zero result here */
|
|
|
|
#ifdef PARANOID
|
|
jb L_bugged_1
|
|
#endif /* PARANOID */
|
|
|
|
/* need to subtract another once of the denom */
|
|
incl FPU_result_2 /* Correct the answer */
|
|
|
|
movl SIGL(%ebx),%eax
|
|
movl SIGH(%ebx),%edx
|
|
subl %eax,FPU_accum_1 /* Subtract from the num local reg */
|
|
sbbl %edx,FPU_accum_2
|
|
|
|
#ifdef PARANOID
|
|
sbbl $0,FPU_accum_3
|
|
jne L_bugged_1 /* Must check for non-zero result here */
|
|
#endif /* PARANOID */
|
|
|
|
/*----------------------------------------------------------------------*/
|
|
/* Half of the main problem is done, there is just a reduced numerator
|
|
to handle now.
|
|
Work with the second 32 bits, FPU_accum_0 not used from now on */
|
|
LDo_2nd_32_bits:
|
|
movl FPU_accum_2,%edx /* get the reduced num */
|
|
movl FPU_accum_1,%eax
|
|
|
|
/* need to check for possible subsequent overflow */
|
|
cmpl SIGH(%ebx),%edx
|
|
jb LDo_2nd_div
|
|
ja LPrevent_2nd_overflow
|
|
|
|
cmpl SIGL(%ebx),%eax
|
|
jb LDo_2nd_div
|
|
|
|
LPrevent_2nd_overflow:
|
|
/* The numerator is greater or equal, would cause overflow */
|
|
/* prevent overflow */
|
|
subl SIGL(%ebx),%eax
|
|
sbbl SIGH(%ebx),%edx
|
|
movl %edx,FPU_accum_2
|
|
movl %eax,FPU_accum_1
|
|
|
|
incl FPU_result_2 /* Reflect the subtraction in the answer */
|
|
|
|
#ifdef PARANOID
|
|
je L_bugged_2 /* Can't bump the result to 1.0 */
|
|
#endif /* PARANOID */
|
|
|
|
LDo_2nd_div:
|
|
cmpl $0,%ecx /* augmented denom msw */
|
|
jnz LSecond_div_not_1
|
|
|
|
/* %ecx == 0, we are dividing by 1.0 */
|
|
mov %edx,%eax
|
|
jmp LSecond_div_done
|
|
|
|
LSecond_div_not_1:
|
|
divl %ecx /* Divide the numerator by the denom ms dw */
|
|
|
|
LSecond_div_done:
|
|
movl %eax,FPU_result_1 /* Put the result in the answer */
|
|
|
|
mull SIGH(%ebx) /* mul by the ms dw of the denom */
|
|
|
|
subl %eax,FPU_accum_1 /* Subtract from the num local reg */
|
|
sbbl %edx,FPU_accum_2
|
|
|
|
#ifdef PARANOID
|
|
jc L_bugged_2
|
|
#endif /* PARANOID */
|
|
|
|
movl FPU_result_1,%eax /* Get the result back */
|
|
mull SIGL(%ebx) /* now mul the ls dw of the denom */
|
|
|
|
subl %eax,FPU_accum_0 /* Subtract from the num local reg */
|
|
sbbl %edx,FPU_accum_1 /* Subtract from the num local reg */
|
|
sbbl $0,FPU_accum_2
|
|
|
|
#ifdef PARANOID
|
|
jc L_bugged_2
|
|
#endif /* PARANOID */
|
|
|
|
jz LDo_3rd_32_bits
|
|
|
|
#ifdef PARANOID
|
|
cmpl $1,FPU_accum_2
|
|
jne L_bugged_2
|
|
#endif /* PARANOID */
|
|
|
|
/* need to subtract another once of the denom */
|
|
movl SIGL(%ebx),%eax
|
|
movl SIGH(%ebx),%edx
|
|
subl %eax,FPU_accum_0 /* Subtract from the num local reg */
|
|
sbbl %edx,FPU_accum_1
|
|
sbbl $0,FPU_accum_2
|
|
|
|
#ifdef PARANOID
|
|
jc L_bugged_2
|
|
jne L_bugged_2
|
|
#endif /* PARANOID */
|
|
|
|
addl $1,FPU_result_1 /* Correct the answer */
|
|
adcl $0,FPU_result_2
|
|
|
|
#ifdef PARANOID
|
|
jc L_bugged_2 /* Must check for non-zero result here */
|
|
#endif /* PARANOID */
|
|
|
|
/*----------------------------------------------------------------------*/
|
|
/* The division is essentially finished here, we just need to perform
|
|
tidying operations.
|
|
Deal with the 3rd 32 bits */
|
|
LDo_3rd_32_bits:
|
|
movl FPU_accum_1,%edx /* get the reduced num */
|
|
movl FPU_accum_0,%eax
|
|
|
|
/* need to check for possible subsequent overflow */
|
|
cmpl SIGH(%ebx),%edx /* denom */
|
|
jb LRound_prep
|
|
ja LPrevent_3rd_overflow
|
|
|
|
cmpl SIGL(%ebx),%eax /* denom */
|
|
jb LRound_prep
|
|
|
|
LPrevent_3rd_overflow:
|
|
/* prevent overflow */
|
|
subl SIGL(%ebx),%eax
|
|
sbbl SIGH(%ebx),%edx
|
|
movl %edx,FPU_accum_1
|
|
movl %eax,FPU_accum_0
|
|
|
|
addl $1,FPU_result_1 /* Reflect the subtraction in the answer */
|
|
adcl $0,FPU_result_2
|
|
jne LRound_prep
|
|
jnc LRound_prep
|
|
|
|
/* This is a tricky spot, there is an overflow of the answer */
|
|
movb $255,FPU_ovfl_flag /* Overflow -> 1.000 */
|
|
|
|
LRound_prep:
|
|
/*
|
|
* Prepare for rounding.
|
|
* To test for rounding, we just need to compare 2*accum with the
|
|
* denom.
|
|
*/
|
|
movl FPU_accum_0,%ecx
|
|
movl FPU_accum_1,%edx
|
|
movl %ecx,%eax
|
|
orl %edx,%eax
|
|
jz LRound_ovfl /* The accumulator contains zero. */
|
|
|
|
/* Multiply by 2 */
|
|
clc
|
|
rcll $1,%ecx
|
|
rcll $1,%edx
|
|
jc LRound_large /* No need to compare, denom smaller */
|
|
|
|
subl SIGL(%ebx),%ecx
|
|
sbbl SIGH(%ebx),%edx
|
|
jnc LRound_not_small
|
|
|
|
movl $0x70000000,%eax /* Denom was larger */
|
|
jmp LRound_ovfl
|
|
|
|
LRound_not_small:
|
|
jnz LRound_large
|
|
|
|
movl $0x80000000,%eax /* Remainder was exactly 1/2 denom */
|
|
jmp LRound_ovfl
|
|
|
|
LRound_large:
|
|
movl $0xff000000,%eax /* Denom was smaller */
|
|
|
|
LRound_ovfl:
|
|
/* We are now ready to deal with rounding, but first we must get
|
|
the bits properly aligned */
|
|
testb $255,FPU_ovfl_flag /* was the num > denom ? */
|
|
je LRound_precision
|
|
|
|
incw EXP(%edi)
|
|
|
|
/* shift the mantissa right one bit */
|
|
stc /* Will set the ms bit */
|
|
rcrl FPU_result_2
|
|
rcrl FPU_result_1
|
|
rcrl %eax
|
|
|
|
/* Round the result as required */
|
|
LRound_precision:
|
|
decw EXP(%edi) /* binary point between 1st & 2nd bits */
|
|
|
|
movl %eax,%edx
|
|
movl FPU_result_1,%ebx
|
|
movl FPU_result_2,%eax
|
|
jmp fpu_reg_round
|
|
|
|
|
|
#ifdef PARANOID
|
|
/* The logic is wrong if we got here */
|
|
L_bugged:
|
|
pushl EX_INTERNAL|0x202
|
|
call EXCEPTION
|
|
pop %ebx
|
|
jmp L_exit
|
|
|
|
L_bugged_1:
|
|
pushl EX_INTERNAL|0x203
|
|
call EXCEPTION
|
|
pop %ebx
|
|
jmp L_exit
|
|
|
|
L_bugged_2:
|
|
pushl EX_INTERNAL|0x204
|
|
call EXCEPTION
|
|
pop %ebx
|
|
jmp L_exit
|
|
|
|
L_exit:
|
|
movl $-1,%eax
|
|
popl %ebx
|
|
popl %edi
|
|
popl %esi
|
|
|
|
leave
|
|
ret
|
|
#endif /* PARANOID */
|