i386: move math-emu

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

1 files changed, 471 insertions, 0 deletions

diff --git a/arch/x86/math-emu/reg_u_div.S b/arch/x86/math-emu/reg_u_div.S
new file mode 100644
index 00000000000..cc00654b6f9
--- /dev/null
+++ b/arch/x86/math-emu/reg_u_div.S
@@ -0,0 +1,471 @@
+	.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 */