mu - Soul of a tiny new machine. More thorough tests → More comprehensible and rewrite-friendly software → More resilient society.

	Commit message (Expand)	Author	Age	Files	Lines
*	3905	Kartik K. Agaram	2017-06-10	1	-1/+0
*	3861 - screen untouched when entering console mode	Kartik K. Agaram	2017-05-18	1	-0/+1
*	3483	Kartik K. Agaram	2016-10-08	1	-1/+1
*	2735 - define recipes using 'def'	Kartik K. Agaram	2016-03-08	1	-1/+1
*	2652 - fix issue #4	Kartik K. Agaram	2016-02-13	1	-0/+1
*	2132 - support for ctrl + arrow keys	Kartik K. Agaram	2015-09-02	1	-1/+2
*	1880 - switch .mu files to new type-deducing idiom	Kartik K. Agaram	2015-07-29	1	-1/+1
*	1868 - start using naked literals everywhere	Kartik K. Agaram	2015-07-28	1	-1/+1
*	1618	Kartik K. Agaram	2015-06-21	1	-2/+2
*	1617	Kartik K. Agaram	2015-06-21	1	-0/+14

<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01//EN" "http://www.w3.org/TR/html4/strict.dtd"> <html> <head> <meta http-equiv="content-type" content="text/html; charset=UTF-8"> <title>Mu - subx/examples/ex11.subx</title> <meta name="Generator" content="Vim/8.0"> <meta name="plugin-version" content="vim7.4_v2"> <meta name="syntax" content="none"> <meta name="settings" content="number_lines,use_css,no_foldcolumn,expand_tabs,line_ids,prevent_copy="> <meta name="colorscheme" content="minimal"> <style type="text/css">  </style> <script type='text/javascript'>  </script> </head> <body onload='JumpToLine();'> <a href='https://github.com/akkartik/mu/blob/master/subx/examples/ex11.subx'>https://github.com/akkartik/mu/blob/master/subx/examples/ex11.subx</a> <pre id='vimCodeElement'> 1 # Null-terminated vs length-prefixed ascii strings. 2 # 3 # By default we create strings with a 4-byte length prefix rather than a null suffix. 4 # However we still need null-prefixed strings when interacting with the Linux 5 # kernel in a few places. This layer implements a function for comparing 6 # a null-terminated 'kernel string' with a length-prefixed 'SubX string'. 7 # 8 # To run (from the subx directory): 9 # $ subx translate examples/ex11.subx -o examples/ex11 10 # $ subx run examples/ex11 # runs a series of tests 11 # ...... # all tests pass 12 # 13 # (We can't yet run the tests when given a "test" commandline argument, 14 # because checking for it would require the function being tested! Breakage 15 # would cause tests to not run, rather than to fail as we'd like.) 16 17 == code 18 # instruction effective address register displacement immediate 19 # . op subop mod rm32 base index scale r32 20 # . 1-3 bytes 3 bits 2 bits 3 bits 3 bits 3 bits 2 bits 2 bits 0/1/2/4 bytes 0/1/2/4 bytes 21 22 # main: 23 e8/call run-tests/disp32 # 'run-tests' is a function created automatically by SubX. It calls all functions that start with 'test-'. 24 # syscall(exit, EAX) 25 89/copy 3/mod/direct 3/rm32/EBX . . . 0/r32/EAX . . # copy EAX to EBX 26 b8/copy-to-EAX 1/imm32 27 cd/syscall 0x80/imm8 28 29 # compare a null-terminated ascii string with a more idiomatic length-prefixed byte array 30 # reason for the name: the only place we should have null-terminated ascii strings is from commandline args 31 kernel-string-equal: # s : null-terminated ascii string, benchmark : length-prefixed ascii string -> EAX : boolean 32 # . prolog 33 55/push-EBP 34 89/copy 3/mod/direct 5/rm32/EBP . . . 4/r32/ESP . . # copy ESP to EBP 35 # . save registers 36 51/push-ECX 37 52/push-EDX 38 53/push-EBX 39 56/push-ESI 40 57/push-EDI 41 42 # pseudocode: 43 # initialize n = b->length 44 # initialize s1 = s 45 # initialize s2 = b->data 46 # i = 0 47 # for (i = 0; i < n; ++n) 48 # c1 = *s1 49 # c2 = *s2 50 # if c1 == 0 51 # return false 52 # if c1 != c2 53 # return false 54 # return *s1 == 0 55 # initialize s into EDI 56 8b/copy 1/mod/*+disp8 4/rm32/sib 5/base/EBP 4/index/none . 7/r32/EDI 8/disp8 . # copy *(EBP+8) to EDI 57 # initialize benchmark length n into EDX 58 8b/copy 1/mod/*+disp8 4/rm32/sib 5/base/EBP 4/index/none . 2/r32/EDX 0xc/disp8 . # copy *(EBP+12) to EDX 59 8b/copy 0/mod/indirect 2/rm32/EDX . . . 2/r32/EDX . . # copy *EDX to EDX 60 # initialize benchmark data into ESI 61 8b/copy 1/mod/*+disp8 4/rm32/sib 5/base/EBP 4/index/none . 6/r32/ESI 0xc/disp8 . # copy *(EBP+12) to ESI 62 81 0/subop/add 3/mod/direct 6/rm32/ESI . . . . . 4/imm32 # add to ESI 63 # initialize loop counter i into ECX 64 b9/copy-to-ECX 0/imm32/exit 65 # while (i/ECX < n/EDX) 66 $kernel-string-equal:loop: 67 39/compare 3/mod/direct 1/rm32/ECX . . . 2/r32/EDX . . # compare ECX with EDX 68 74/jump-if-equal $kernel-string-equal:break/disp8 69 # c1/EAX, c2/EBX = *s, *benchmark 70 b8/copy-to-EAX 0/imm32 71 8a/copy 0/mod/indirect 7/rm32/EDI . . . 0/r32/EAX . . # copy byte at *EDI to lower byte of EAX 72 bb/copy-to-EBX 0/imm32 73 8a/copy 0/mod/indirect 6/rm32/ESI . . . 3/r32/EBX . . # copy byte at *ESI to lower byte of EBX 74 # if (c1 == 0) return false 75 3d/compare-EAX 0/imm32 76 74/jump-if-equal $kernel-string-equal:false/disp8 77 # if (c1 != c2) return false 78 39/compare 3/mod/direct 0/rm32/EAX . . . 3/r32/EBX . . # compare EAX with EBX 79 75/jump-if-not-equal $kernel-string-equal:false/disp8 80 # ++s1, ++s2, ++i 81 41/inc-ECX 82 46/inc-ESI 83 47/inc-EDI 84 # end while 85 eb/jump $kernel-string-equal:loop/disp8 86 $kernel-string-equal:break: 87 # if (*s/EDI == 0) return true 88 b8/copy-to-EAX 0/imm32 89 8a/copy 0/mod/indirect 7/rm32/EDI . . . 0/r32/EAX . . # copy byte at *EDI to lower byte of EAX 90 81 7/subop/compare 3/mod/direct 0/rm32/EAX . . . . . 0/imm32 # compare EAX 91 75/jump-if-not-equal $kernel-string-equal:false/disp8 92 b8/copy-to-EAX 1/imm32 93 $kernel-string-equal:true: 94 eb/jump $kernel-string-equal:end/disp8 95 # return false 96 $kernel-string-equal:false: 97 b8/copy-to-EAX 0/imm32 98 99 $kernel-string-equal:end: 100 # . restore registers 101 5f/pop-to-EDI 102 5e/pop-to-ESI 103 5b/pop-to-EBX 104 5a/pop-to-EDX 105 59/pop-to-ECX 106 # end 107 89/copy 3/mod/direct 4/rm32/ESP . . . 5/r32/EBP . . # copy EBP to ESP 108 5d/pop-to-EBP 109 c3/return 110 111 # - tests 112 113 test-compare-null-kernel-string-with-empty-array: 114 # EAX = kernel-string-equal(Null-kernel-string, "") 115 # . . push args 116 68/push ""/imm32 117 68/push Null-kernel-string/imm32 118 # . . call 119 e8/call kernel-string-equal/disp32 120 # . . discard args 121 81 0/subop/add 3/mod/direct 4/rm32/ESP . . . . . 8/imm32 # add to ESP 122 # check-ints-equal(EAX, 1, msg) 123 # . . push args 124 68/push "F - test-compare-null-kernel-string-with-empty-array"/imm32 125 68/push 1/imm32/true 126 50/push-EAX 127 # . . call 128 e8/call check-ints-equal/disp32 129 # . . discard args 130 81 0/subop/add 3/mod/direct 4/rm32/ESP . . . . . 0xc/imm32 # add to ESP 131 c3/return 132 133 test-compare-null-kernel-string-with-non-empty-array: 134 # EAX = kernel-string-equal(Null-kernel-string, "Abc") 135 # . . push args 136 68/push "Abc"/imm32 137 68/push Null-kernel-string/imm32 138 # . . call 139 e8/call kernel-string-equal/disp32 140 # . . discard args 141 81 0/subop/add 3/mod/direct 4/rm32/ESP . . . . . 8/imm32 # add to ESP 142 # check-ints-equal(EAX, 0, msg) 143 # . . push args 144 68/push "F - test-compare-null-kernel-string-with-non-empty-array"/imm32 145 68/push 0/imm32/false 146 50/push-EAX 147 # . . call 148 e8/call check-ints-equal/disp32 149 # . . discard args 150 81 0/subop/add 3/mod/direct 4/rm32/ESP . . . . . 0xc/imm32 # add to ESP 151 c3/return 152 153 test-compare-kernel-string-with-equal-array: 154 # EAX = kernel-string-equal(Abc-kernel-string, "Abc") 155 # . . push args 156 68/push "Abc"/imm32 157 68/push Abc-kernel-string/imm32 158 # . . call 159 e8/call kernel-string-equal/disp32 160 # . . discard args 161 81 0/subop/add 3/mod/direct 4/rm32/ESP . . . . . 8/imm32 # add to ESP 162 # check-ints-equal(EAX, 1, msg) 163 # . . push args 164 68/push "F - test-compare-kernel-string-with-equal-array"/imm32 165 68/push 1/imm32/true 166 50/push-EAX 167 # . . call 168 e8/call check-ints-equal/disp32 169 # . . discard args 170 81 0/subop/add 3/mod/direct 4/rm32/ESP . . . . . 0xc/imm32 # add to ESP 171 c3/return 172 173 test-compare-kernel-string-with-inequal-array: 174 # EAX = kernel-string-equal(Abc-kernel-string, "Adc") 175 # . . push args 176 68/push "Adc"/imm32 177 68/push Abc-kernel-string/imm32 178 # . . call 179 e8/call kernel-string-equal/disp32 180 # . . discard args 181 81 0/subop/add 3/mod/direct 4/rm32/ESP . . . . . 8/imm32 # add to ESP 182 # check-ints-equal(EAX, 0, msg) 183 # . . push args 184 68/push "F - test-compare-kernel-string-with-equal-array"/imm32 185 68/push 0/imm32/false 186 50/push-EAX 187 # . . call 188 e8/call check-ints-equal/disp32 189 # . . discard args 190 81 0/subop/add 3/mod/direct 4/rm32/ESP . . . . . 0xc/imm32 # add to ESP 191 c3/return 192 193 test-compare-kernel-string-with-empty-array: 194 # EAX = kernel-string-equal(Abc-kernel-string, "") 195 # . . push args 196 68/push ""/imm32 197 68/push Abc-kernel-string/imm32 198 # . . call 199 e8/call kernel-string-equal/disp32 200 # . . discard args 201 81 0/subop/add 3/mod/direct 4/rm32/ESP . . . . . 8/imm32 # add to ESP 202 # check-ints-equal(EAX, 0, msg) 203 # . . push args 204 68/push "F - test-compare-kernel-string-with-equal-array"/imm32 205 68/push 0/imm32/false 206 50/push-EAX 207 # . . call 208 e8/call check-ints-equal/disp32 209 # . . discard args 210 81 0/subop/add 3/mod/direct 4/rm32/ESP . . . . . 0xc/imm32 # add to ESP 211 c3/return 212 213 test-compare-kernel-string-with-shorter-array: 214 # EAX = kernel-string-equal(Abc-kernel-string, "Ab") 215 # . . push args 216 68/push "Ab"/imm32 217 68/push Abc-kernel-string/imm32 218 # . . call 219 e8/call kernel-string-equal/disp32 220 # . . discard args 221 81 0/subop/add 3/mod/direct 4/rm32/ESP . . . . . 8/imm32 # add to ESP 222 # check-ints-equal(EAX, 0, msg) 223 # . . push args 224 68/push "F - test-compare-kernel-string-with-shorter-array"/imm32 225 68/push 0/imm32/false 226 50/push-EAX 227 # . . call 228 e8/call check-ints-equal/disp32 229 # . . discard args 230 81 0/subop/add 3/mod/direct 4/rm32/ESP . . . . . 0xc/imm32 # add to ESP 231 c3/return 232 233 test-compare-kernel-string-with-longer-array: 234 # EAX = kernel-string-equal(Abc-kernel-string, "Abcd") 235 # . . push args 236 68/push "Abcd"/imm32 237 68/push Abc-kernel-string/imm32 238 # . . call 239 e8/call kernel-string-equal/disp32 240 # . . discard args 241 81 0/subop/add 3/mod/direct 4/rm32/ESP . . . . . 8/imm32 # add to ESP 242 # check-ints-equal(EAX, 0, msg) 243 # . . push args 244 68/push "F - test-compare-kernel-string-with-longer-array"/imm32 245 68/push 0/imm32/false 246 50/push-EAX 247 # . . call 248 e8/call check-ints-equal/disp32 249 # . . discard args 250 81 0/subop/add 3/mod/direct 4/rm32/ESP . . . . . 0xc/imm32 # add to ESP 251 c3/return 252 253 # - helpers 254 255 # print msg to stderr if a != b, otherwise print "." 256 check-ints-equal: # (a : int, b : int, msg : (address array byte)) -> boolean 257 # . prolog 258 55/push-EBP 259 89/copy 3/mod/direct 5/rm32/EBP . . . 4/r32/ESP . . # copy ESP to EBP 260 # . save registers 261 51/push-ECX 262 53/push-EBX 263 # load args into EAX, EBX and ECX 264 8b/copy 1/mod/*+disp8 4/rm32/sib 5/base/EBP 4/index/none . 0/r32/EAX 0x8/disp8 . # copy *(EBP+8) to EAX 265 8b/copy 1/mod/*+disp8 4/rm32/sib 5/base/EBP 4/index/none . 3/r32/EBX 0xc/disp8 . # copy *(EBP+12) to EBX 266 # if EAX == b/EBX print('.') and return 267 39/compare 3/mod/direct 0/rm32/EAX . . . 3/r32/EBX . . # compare EAX and EBX 268 75/jump-if-unequal $check-ints-equal:else/disp8 269 # . write-stderr('.') 270 # . . push args 271 68/push "."/imm32 272 # . . call 273 e8/call write-stderr/disp32 274 # . . discard args 275 81 0/subop/add 3/mod/direct 4/rm32/ESP . . . . . 4/imm32 # add to ESP 276 # . return 277 eb/jump $check-ints-equal:end/disp8 278 # otherwise print(msg) 279 $check-ints-equal:else: 280 # copy msg into ECX 281 8b/copy 1/mod/*+disp8 4/rm32/sib 5/base/EBP 4/index/none . 1/r32/ECX 0x10/disp8 . # copy *(EBP+16) to ECX 282 # print(ECX) 283 # . . push args 284 51/push-ECX 285 # . . call 286 e8/call write-stderr/disp32 287 # . . discard args 288 81 0/subop/add 3/mod/direct 4/rm32/ESP . . . . . 4/imm32 # add to ESP 289 # print newline 290 # . . push args 291 68/push Newline/imm32 292 # . . call 293 e8/call write-stderr/disp32 294 # . . discard args 295 81 0/subop/add 3/mod/direct 4/rm32/ESP . . . . . 4/imm32 # add to ESP 296 $check-ints-equal:end: 297 # . restore registers 298 5b/pop-to-EBX 299 59/pop-to-ECX 300 # end 301 89/copy 3/mod/direct 4/rm32/ESP . . . 5/r32/EBP . . # copy EBP to ESP 302 5d/pop-to-EBP 303 c3/return 304 305 write-stderr: # s : (address array byte) -> <void> 306 # . prolog 307 55/push-EBP 308 89/copy 3/mod/direct 5/rm32/EBP . . . 4/r32/ESP . . # copy ESP to EBP 309 # . save registers 310 50/push-EAX 311 51/push-ECX 312 52/push-EDX 313 53/push-EBX 314 # syscall(write, 2/stderr, (data) s+4, (size) *s) 315 # . . fd = 2 (stderr) 316 bb/copy-to-EBX 2/imm32 317 # . . x = s+4 318 8b/copy 1/mod/*+disp8 4/rm32/sib 5/base/EBP 4/index/none . 1/r32/ECX 8/disp8 . # copy *(EBP+8) to ECX 319 81 0/subop/add 3/mod/direct 1/rm32/ECX . . . . . 4/imm32 # add to ECX 320 # . . size = *s 321 8b/copy 1/mod/*+disp8 4/rm32/sib 5/base/EBP 4/index/none . 2/r32/EDX 8/disp8 . # copy *(EBP+8) to EDX 322 8b/copy 0/mod/indirect 2/rm32/EDX . . . 2/r32/EDX . . # copy *EDX to EDX 323 # . . syscall 324 b8/copy-to-EAX 4/imm32/write 325 cd/syscall 0x80/imm8 326 # . restore registers 327 5b/pop-to-EBX 328 5a/pop-to-EDX 329 59/pop-to-ECX 330 58/pop-to-EAX 331 # . end 332 89/copy 3/mod/direct 4/rm32/ESP . . . 5/r32/EBP . . # copy EBP to ESP 333 5d/pop-to-EBP 334 c3/return 335 336 == data 337 338 Newline: 339 # size 340 01 00 00 00 341 # data 342 0a/newline 343 344 # for kernel-string-equal tests 345 Null-kernel-string: 346 00/null 347 Abc-kernel-string: 348 41/A 62/b 63/c 00/null 349 350 # . . vim:nowrap:textwidth=0 </pre> </body> </html>