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 25 SYM_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 */ 47 L_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 58 L_done: 59 cmpw EXP_OVER,EXP(%ebx) 60 jge L_overflow 61 62 cmpw EXP_UNDER,EXP(%ebx) 63 jle L_underflow 64 65 L_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 72 L_exit: 73 popl %ebx 74 leave 75 RET 76 77 78 L_zero: 79 movw $0,EXP(%ebx) 80 movl TAG_Zero,%eax 81 jmp L_exit 82 83 L_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 91 L_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 98 SYM_FUNC_END(FPU_normalize) 99 100 101 102 /* Normalise without reporting underflow or overflow */ 103 SYM_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 */ 125 L_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) 135 136 L_exit_nuo_valid: 137 movl TAG_Valid,%eax 138 139 popl %ebx 140 leave 141 RET 142 143 L_exit_nuo_zero: 144 movl TAG_Zero,%eax 145 movw EXP_UNDER,EXP(%ebx) 146 147 popl %ebx 148 leave 149 RET 150 SYM_FUNC_END(FPU_normalize_nuo)
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