1/* SPDX-License-Identifier: GPL-2.0 */
  2/*---------------------------------------------------------------------------+
  3 |  reg_norm.S                                                               |
  4 |                                                                           |
  5 | Copyright (C) 1992,1993,1994,1995,1997                                    |
  6 |                       W. Metzenthen, 22 Parker St, Ormond, Vic 3163,      |
  7 |                       Australia.  E-mail billm@suburbia.net               |
  8 |                                                                           |
  9 | Normalize the value in a FPU_REG.                                         |
 10 |                                                                           |
 11 | Call from C as:                                                           |
 12 |    int FPU_normalize(FPU_REG *n)                                          |
 13 |                                                                           |
 14 |    int FPU_normalize_nuo(FPU_REG *n)                                      |
 15 |                                                                           |
 16 |    Return value is the tag of the answer, or-ed with FPU_Exception if     |
 17 |    one was raised, or -1 on internal error.                               |
 18 |                                                                           |
 19 +---------------------------------------------------------------------------*/
 20
 21#include "fpu_emu.h"
 22
 23
 24.text
 25SYM_FUNC_START(FPU_normalize)
 26	pushl	%ebp
 27	movl	%esp,%ebp
 28	pushl	%ebx
 29
 30	movl	PARAM1,%ebx
 31
 32	movl	SIGH(%ebx),%edx
 33	movl	SIGL(%ebx),%eax
 34
 35	orl	%edx,%edx	/* ms bits */
 36	js	L_done		/* Already normalized */
 37	jnz	L_shift_1	/* Shift left 1 - 31 bits */
 38
 39	orl	%eax,%eax
 40	jz	L_zero		/* The contents are zero */
 41
 42	movl	%eax,%edx
 43	xorl	%eax,%eax
 44	subw	$32,EXP(%ebx)	/* This can cause an underflow */
 45
 46/* We need to shift left by 1 - 31 bits */
 47L_shift_1:
 48	bsrl	%edx,%ecx	/* get the required shift in %ecx */
 49	subl	$31,%ecx
 50	negl	%ecx
 51	shld	%cl,%eax,%edx
 52	shl	%cl,%eax
 53	subw	%cx,EXP(%ebx)	/* This can cause an underflow */
 54
 55	movl	%edx,SIGH(%ebx)
 56	movl	%eax,SIGL(%ebx)
 57
 58L_done:
 59	cmpw	EXP_OVER,EXP(%ebx)
 60	jge	L_overflow
 61
 62	cmpw	EXP_UNDER,EXP(%ebx)
 63	jle	L_underflow
 64
 65L_exit_valid:
 66	movl	TAG_Valid,%eax
 67
 68	/* Convert the exponent to 80x87 form. */
 69	addw	EXTENDED_Ebias,EXP(%ebx)
 70	andw	$0x7fff,EXP(%ebx)
 71
 72L_exit:
 73	popl	%ebx
 74	leave
 75	RET
 76
 77
 78L_zero:
 79	movw	$0,EXP(%ebx)
 80	movl	TAG_Zero,%eax
 81	jmp	L_exit
 82
 83L_underflow:
 84	/* Convert the exponent to 80x87 form. */
 85	addw	EXTENDED_Ebias,EXP(%ebx)
 86	push	%ebx
 87	call	arith_underflow
 88	pop	%ebx
 89	jmp	L_exit
 90
 91L_overflow:
 92	/* Convert the exponent to 80x87 form. */
 93	addw	EXTENDED_Ebias,EXP(%ebx)
 94	push	%ebx
 95	call	arith_overflow
 96	pop	%ebx
 97	jmp	L_exit
 98SYM_FUNC_END(FPU_normalize)
 99
100
101
102/* Normalise without reporting underflow or overflow */
103SYM_FUNC_START(FPU_normalize_nuo)
104	pushl	%ebp
105	movl	%esp,%ebp
106	pushl	%ebx
107
108	movl	PARAM1,%ebx
109
110	movl	SIGH(%ebx),%edx
111	movl	SIGL(%ebx),%eax
112
113	orl	%edx,%edx	/* ms bits */
114	js	L_exit_nuo_valid	/* Already normalized */
115	jnz	L_nuo_shift_1	/* Shift left 1 - 31 bits */
116
117	orl	%eax,%eax
118	jz	L_exit_nuo_zero		/* The contents are zero */
119
120	movl	%eax,%edx
121	xorl	%eax,%eax
122	subw	$32,EXP(%ebx)	/* This can cause an underflow */
123
124/* We need to shift left by 1 - 31 bits */
125L_nuo_shift_1:
126	bsrl	%edx,%ecx	/* get the required shift in %ecx */
127	subl	$31,%ecx
128	negl	%ecx
129	shld	%cl,%eax,%edx
130	shl	%cl,%eax
131	subw	%cx,EXP(%ebx)	/* This can cause an underflow */
132
133	movl	%edx,SIGH(%ebx)
134	movl	%eax,SIGL(%ebx)
135
136L_exit_nuo_valid:
137	movl	TAG_Valid,%eax
138
139	popl	%ebx
140	leave
141	RET
142
143L_exit_nuo_zero:
144	movl	TAG_Zero,%eax
145	movw	EXP_UNDER,EXP(%ebx)
146
147	popl	%ebx
148	leave
149	RET
150SYM_FUNC_END(FPU_normalize_nuo)