| b.liu | e958203 | 2025-04-17 19:18:16 +0800 | [diff] [blame] | 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 | ENTRY(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 | ENDPROC(FPU_normalize) |
| 99 | |
| 100 | |
| 101 | |
| 102 | /* Normalise without reporting underflow or overflow */ |
| 103 | ENTRY(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 | ENDPROC(FPU_normalize_nuo) |