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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 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 | .file "reg_u_add.S" /*---------------------------------------------------------------------------+ | reg_u_add.S | | | | Add two valid (TAG_Valid) FPU_REG numbers, of the same sign, 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_add(FPU_REG *arg1, FPU_REG *arg2, FPU_REG *answ, | | int control_w) | | Return value is the tag of the answer, or-ed with FPU_Exception if | | one was raised, or -1 on internal error. | | | +---------------------------------------------------------------------------*/ /* | Kernel addition routine FPU_u_add(reg *arg1, reg *arg2, reg *answ). | Takes two valid reg f.p. numbers (TAG_Valid), which are | treated as unsigned numbers, | and returns their sum as a TAG_Valid or TAG_Special f.p. number. | The returned number is normalized. | Basic checks are performed if PARANOID is defined. */ #include "exception.h" #include "fpu_emu.h" #include "control_w.h" .text ENTRY(FPU_u_add) pushl %ebp movl %esp,%ebp pushl %esi pushl %edi pushl %ebx movl PARAM1,%esi /* source 1 */ movl PARAM2,%edi /* source 2 */ movl PARAM6,%ecx movl %ecx,%edx subl PARAM7,%ecx /* exp1 - exp2 */ jge L_arg1_larger /* num1 is smaller */ movl SIGL(%esi),%ebx movl SIGH(%esi),%eax movl %edi,%esi movl PARAM7,%edx negw %cx jmp L_accum_loaded L_arg1_larger: /* num1 has larger or equal exponent */ movl SIGL(%edi),%ebx movl SIGH(%edi),%eax L_accum_loaded: movl PARAM3,%edi /* destination */ movw %dx,EXP(%edi) /* Copy exponent to destination */ xorl %edx,%edx /* clear the extension */ #ifdef PARANOID testl $0x80000000,%eax je L_bugged testl $0x80000000,SIGH(%esi) je L_bugged #endif /* PARANOID */ /* The number to be shifted is in %eax:%ebx:%edx */ cmpw $32,%cx /* shrd only works for 0..31 bits */ jnc L_more_than_31 /* less than 32 bits */ shrd %cl,%ebx,%edx shrd %cl,%eax,%ebx shr %cl,%eax jmp L_shift_done L_more_than_31: cmpw $64,%cx jnc L_more_than_63 subb $32,%cl jz L_exactly_32 shrd %cl,%eax,%edx shr %cl,%eax orl %ebx,%ebx jz L_more_31_no_low /* none of the lowest bits is set */ orl $1,%edx /* record the fact in the extension */ L_more_31_no_low: movl %eax,%ebx xorl %eax,%eax jmp L_shift_done L_exactly_32: movl %ebx,%edx movl %eax,%ebx xorl %eax,%eax jmp L_shift_done L_more_than_63: cmpw $65,%cx jnc L_more_than_64 movl %eax,%edx orl %ebx,%ebx jz L_more_63_no_low orl $1,%edx jmp L_more_63_no_low L_more_than_64: movl $1,%edx /* The shifted nr always at least one '1' */ L_more_63_no_low: xorl %ebx,%ebx xorl %eax,%eax L_shift_done: /* Now do the addition */ addl SIGL(%esi),%ebx adcl SIGH(%esi),%eax jnc L_round_the_result /* Overflow, adjust the result */ rcrl $1,%eax rcrl $1,%ebx rcrl $1,%edx jnc L_no_bit_lost orl $1,%edx L_no_bit_lost: incw EXP(%edi) L_round_the_result: jmp fpu_reg_round /* Round the result */ #ifdef PARANOID /* If we ever get here then we have problems! */ L_bugged: pushl EX_INTERNAL|0x201 call EXCEPTION pop %ebx movl $-1,%eax jmp L_exit L_exit: popl %ebx popl %edi popl %esi leave ret #endif /* PARANOID */ |