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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 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 | .file "wm_shrx.S" /*---------------------------------------------------------------------------+ | wm_shrx.S | | | | 64 bit right shift functions | | | | Copyright (C) 1992 W. Metzenthen, 22 Parker St, Ormond, Vic 3163, | | Australia. E-mail billm@vaxc.cc.monash.edu.au | | | | Call from C as: | | unsigned shrx(void *arg1, unsigned arg2) | | and | | unsigned shrxs(void *arg1, unsigned arg2) | | | +---------------------------------------------------------------------------*/ #include "fpu_asm.h" .text .align 2,144 /*---------------------------------------------------------------------------+ | unsigned shrx(void *arg1, unsigned arg2) | | | | Extended shift right function. | | Fastest for small shifts. | | Shifts the 64 bit quantity pointed to by the first arg (arg1) | | right by the number of bits specified by the second arg (arg2). | | Forms a 96 bit quantity from the 64 bit arg and eax: | | [ 64 bit arg ][ eax ] | | shift right ---------> | | The eax register is initialized to 0 before the shifting. | | Results returned in the 64 bit arg and eax. | +---------------------------------------------------------------------------*/ .globl _shrx _shrx: push %ebp movl %esp,%ebp pushl %esi movl PARAM2,%ecx movl PARAM1,%esi cmpl $32,%ecx /* shrd only works for 0..31 bits */ jnc L_more_than_31 /* less than 32 bits */ pushl %ebx movl (%esi),%ebx /* lsl */ movl 4(%esi),%edx /* msl */ xorl %eax,%eax /* extension */ shrd %cl,%ebx,%eax shrd %cl,%edx,%ebx shr %cl,%edx movl %ebx,(%esi) movl %edx,4(%esi) popl %ebx popl %esi leave ret L_more_than_31: cmpl $64,%ecx jnc L_more_than_63 subb $32,%cl movl (%esi),%eax /* lsl */ movl 4(%esi),%edx /* msl */ shrd %cl,%edx,%eax shr %cl,%edx movl %edx,(%esi) movl $0,4(%esi) popl %esi leave ret L_more_than_63: cmpl $96,%ecx jnc L_more_than_95 subb $64,%cl movl 4(%esi),%eax /* msl */ shr %cl,%eax xorl %edx,%edx movl %edx,(%esi) movl %edx,4(%esi) popl %esi leave ret L_more_than_95: xorl %eax,%eax movl %eax,(%esi) movl %eax,4(%esi) popl %esi leave ret /*---------------------------------------------------------------------------+ | unsigned shrxs(void *arg1, unsigned arg2) | | | | Extended shift right function (optimized for small floating point | | integers). | | Shifts the 64 bit quantity pointed to by the first arg (arg1) | | right by the number of bits specified by the second arg (arg2). | | Forms a 96 bit quantity from the 64 bit arg and eax: | | [ 64 bit arg ][ eax ] | | shift right ---------> | | The eax register is initialized to 0 before the shifting. | | The lower 8 bits of eax are lost and replaced by a flag which is | | set (to 0x01) if any bit, apart from the first one, is set in the | | part which has been shifted out of the arg. | | Results returned in the 64 bit arg and eax. | +---------------------------------------------------------------------------*/ .globl _shrxs _shrxs: push %ebp movl %esp,%ebp pushl %esi pushl %ebx movl PARAM2,%ecx movl PARAM1,%esi cmpl $64,%ecx /* shrd only works for 0..31 bits */ jnc Ls_more_than_63 cmpl $32,%ecx /* shrd only works for 0..31 bits */ jc Ls_less_than_32 /* We got here without jumps by assuming that the most common requirement is for small integers */ /* Shift by [32..63] bits */ subb $32,%cl movl (%esi),%eax /* lsl */ movl 4(%esi),%edx /* msl */ xorl %ebx,%ebx shrd %cl,%eax,%ebx shrd %cl,%edx,%eax shr %cl,%edx orl %ebx,%ebx /* test these 32 bits */ setne %bl test $0x7fffffff,%eax /* and 31 bits here */ setne %bh orw %bx,%bx /* Any of the 63 bit set ? */ setne %al movl %edx,(%esi) movl $0,4(%esi) popl %ebx popl %esi leave ret /* Shift by [0..31] bits */ Ls_less_than_32: movl (%esi),%ebx /* lsl */ movl 4(%esi),%edx /* msl */ xorl %eax,%eax /* extension */ shrd %cl,%ebx,%eax shrd %cl,%edx,%ebx shr %cl,%edx test $0x7fffffff,%eax /* only need to look at eax here */ setne %al movl %ebx,(%esi) movl %edx,4(%esi) popl %ebx popl %esi leave ret /* Shift by [64..95] bits */ Ls_more_than_63: cmpl $96,%ecx jnc Ls_more_than_95 subb $64,%cl movl (%esi),%ebx /* lsl */ movl 4(%esi),%eax /* msl */ xorl %edx,%edx /* extension */ shrd %cl,%ebx,%edx shrd %cl,%eax,%ebx shr %cl,%eax orl %ebx,%edx setne %bl test $0x7fffffff,%eax /* only need to look at eax here */ setne %bh orw %bx,%bx setne %al xorl %edx,%edx movl %edx,(%esi) /* set to zero */ movl %edx,4(%esi) /* set to zero */ popl %ebx popl %esi leave ret Ls_more_than_95: /* Shift by [96..inf) bits */ xorl %eax,%eax movl (%esi),%ebx orl 4(%esi),%ebx setne %al xorl %ebx,%ebx movl %ebx,(%esi) movl %ebx,4(%esi) popl %ebx popl %esi leave ret |