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