Mu - subx/052kernel-string-equal.subx

From 6e1eeeebfb453fa7c871869c19375ce60fbd7413 Mon Sep 17 00:00:00 2001 From: Kartik Agaram Date: Sat, 27 Jul 2019 16:01:55 -0700 Subject: 5485 - promote SubX to top-level --- html/052kernel-string-equal.subx.html | 333 ++++++++++++++++++++++++++++++++++ 1 file changed, 333 insertions(+) create mode 100644 html/052kernel-string-equal.subx.html (limited to 'html/052kernel-string-equal.subx.html') diff --git a/html/052kernel-string-equal.subx.html b/html/052kernel-string-equal.subx.html new file mode 100644 index 00000000..e7715bbd --- /dev/null +++ b/html/052kernel-string-equal.subx.html @@ -0,0 +1,333 @@ + + + + +Mu - subx/052kernel-string-equal.subx + + + + + + + + + + +https://github.com/akkartik/mu/blob/master/subx/052kernel-string-equal.subx +
+  1 # Checking null-terminated 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 05[0-2]*.subx -o /tmp/tmp52
+ 10 #   $ ./subx run /tmp/tmp52  # 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 Entry:  # run all tests
+ 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, Num-test-failures)
+ 25     8b/copy                         0/mod/indirect  5/rm32/.disp32            .             .           3/r32/EBX   Num-test-failures/disp32          # copy *Num-test-failures to EBX
+ 26     b8/copy-to-EAX  1/imm32/exit
+ 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     # pseudocode:
+ 33     #   n = benchmark->length
+ 34     #   s1 = s
+ 35     #   s2 = benchmark->data
+ 36     #   i = 0
+ 37     #   while (i < n)
+ 38     #     c1 = *s1
+ 39     #     c2 = *s2
+ 40     #     if (c1 == 0) return false
+ 41     #     if (c1 != c2) return false
+ 42     #     ++s1, ++s2, ++i
+ 43     #   return *s1 == 0
+ 44     #
+ 45     # registers:
+ 46     #   i: ECX
+ 47     #   n: EDX
+ 48     #   s1: EDI
+ 49     #   s2: ESI
+ 50     #   c1: EAX
+ 51     #   c2: EBX
+ 52     #
+ 53     # . prolog
+ 54     55/push-EBP
+ 55     89/copy                         3/mod/direct    5/rm32/EBP    .           .             .           4/r32/ESP   .               .                 # copy ESP to EBP
+ 56     # . save registers
+ 57     51/push-ECX
+ 58     52/push-EDX
+ 59     53/push-EBX
+ 60     56/push-ESI
+ 61     57/push-EDI
+ 62     # s1/EDI = s
+ 63     8b/copy                         1/mod/*+disp8   5/rm32/EBP    .           .             .           7/r32/EDI   8/disp8         .                 # copy *(EBP+8) to EDI
+ 64     # n/EDX = benchmark->length
+ 65     8b/copy                         1/mod/*+disp8   5/rm32/EBP    .           .             .           2/r32/EDX   0xc/disp8       .                 # copy *(EBP+12) to EDX
+ 66     8b/copy                         0/mod/indirect  2/rm32/EDX    .           .             .           2/r32/EDX   .               .                 # copy *EDX to EDX
+ 67     # s2/ESI = benchmark->data
+ 68     8b/copy                         1/mod/*+disp8   5/rm32/EBP    .           .             .           6/r32/ESI   0xc/disp8       .                 # copy *(EBP+12) to ESI
+ 69     81          0/subop/add         3/mod/direct    6/rm32/ESI    .           .             .           .           .               4/imm32           # add to ESI
+ 70     # i/ECX = c1/EAX = c2/EBX = 0
+ 71     b9/copy-to-ECX  0/imm32/exit
+ 72     b8/copy-to-EAX  0/imm32
+ 73     bb/copy-to-EBX  0/imm32
+ 74 $kernel-string-equal?:loop:
+ 75     # if (i >= n) break
+ 76     39/compare                      3/mod/direct    1/rm32/ECX    .           .             .           2/r32/EDX   .               .                 # compare ECX with EDX
+ 77     7d/jump-if-greater-or-equal  $kernel-string-equal?:break/disp8
+ 78     # c1 = *s1
+ 79     8a/copy-byte                    0/mod/indirect  7/rm32/EDI    .           .             .           0/r32/AL    .               .                 # copy byte at *EDI to AL
+ 80     # c2 = *s2
+ 81     8a/copy-byte                    0/mod/indirect  6/rm32/ESI    .           .             .           3/r32/BL    .               .                 # copy byte at *ESI to BL
+ 82     # if (c1 == 0) return false
+ 83     3d/compare-EAX-and  0/imm32
+ 84     74/jump-if-equal  $kernel-string-equal?:false/disp8
+ 85     # if (c1 != c2) return false
+ 86     39/compare                      3/mod/direct    0/rm32/EAX    .           .             .           3/r32/EBX   .               .                 # compare EAX and EBX
+ 87     75/jump-if-not-equal  $kernel-string-equal?:false/disp8
+ 88     # ++i
+ 89     41/increment-ECX
+ 90     # ++s1
+ 91     47/increment-EDI
+ 92     # ++s2
+ 93     46/increment-ESI
+ 94     eb/jump  $kernel-string-equal?:loop/disp8
+ 95 $kernel-string-equal?:break:
+ 96     # return *s1 == 0
+ 97     8a/copy-byte                    0/mod/indirect  7/rm32/EDI    .           .             .           0/r32/AL    .               .                 # copy byte at *EDI to AL
+ 98     3d/compare-EAX-and  0/imm32
+ 99     75/jump-if-not-equal  $kernel-string-equal?:false/disp8
+100 $kernel-string-equal?:true:
+101     b8/copy-to-EAX  1/imm32
+102     eb/jump  $kernel-string-equal?:end/disp8
+103 $kernel-string-equal?:false:
+104     b8/copy-to-EAX  0/imm32
+105 $kernel-string-equal?:end:
+106     # . restore registers
+107     5f/pop-to-EDI
+108     5e/pop-to-ESI
+109     5b/pop-to-EBX
+110     5a/pop-to-EDX
+111     59/pop-to-ECX
+112     # . epilog
+113     89/copy                         3/mod/direct    4/rm32/ESP    .           .             .           5/r32/EBP   .               .                 # copy EBP to ESP
+114     5d/pop-to-EBP
+115     c3/return
+116 
+117 # - tests
+118 
+119 test-compare-null-kernel-string-with-empty-array:
+120     # EAX = kernel-string-equal?(Null-kernel-string, "")
+121     # . . push args
+122     68/push  ""/imm32
+123     68/push  Null-kernel-string/imm32
+124     # . . call
+125     e8/call  kernel-string-equal?/disp32
+126     # . . discard args
+127     81          0/subop/add         3/mod/direct    4/rm32/ESP    .           .             .           .           .               8/imm32           # add to ESP
+128     # check-ints-equal(EAX, 1, msg)
+129     # . . push args
+130     68/push  "F - test-compare-null-kernel-string-with-empty-array"/imm32
+131     68/push  1/imm32/true
+132     50/push-EAX
+133     # . . call
+134     e8/call  check-ints-equal/disp32
+135     # . . discard args
+136     81          0/subop/add         3/mod/direct    4/rm32/ESP    .           .             .           .           .               0xc/imm32         # add to ESP
+137     c3/return
+138 
+139 test-compare-null-kernel-string-with-non-empty-array:
+140     # EAX = kernel-string-equal?(Null-kernel-string, "Abc")
+141     # . . push args
+142     68/push  "Abc"/imm32
+143     68/push  Null-kernel-string/imm32
+144     # . . call
+145     e8/call  kernel-string-equal?/disp32
+146     # . . discard args
+147     81          0/subop/add         3/mod/direct    4/rm32/ESP    .           .             .           .           .               8/imm32           # add to ESP
+148     # check-ints-equal(EAX, 0, msg)
+149     # . . push args
+150     68/push  "F - test-compare-null-kernel-string-with-non-empty-array"/imm32
+151     68/push  0/imm32/false
+152     50/push-EAX
+153     # . . call
+154     e8/call  check-ints-equal/disp32
+155     # . . discard args
+156     81          0/subop/add         3/mod/direct    4/rm32/ESP    .           .             .           .           .               0xc/imm32         # add to ESP
+157     c3/return
+158 
+159 test-compare-kernel-string-with-equal-array:
+160     # EAX = kernel-string-equal?(_test-Abc-kernel-string, "Abc")
+161     # . . push args
+162     68/push  "Abc"/imm32
+163     68/push  _test-Abc-kernel-string/imm32
+164     # . . call
+165     e8/call  kernel-string-equal?/disp32
+166     # . . discard args
+167     81          0/subop/add         3/mod/direct    4/rm32/ESP    .           .             .           .           .               8/imm32           # add to ESP
+168     # check-ints-equal(EAX, 1, msg)
+169     # . . push args
+170     68/push  "F - test-compare-kernel-string-with-equal-array"/imm32
+171     68/push  1/imm32/true
+172     50/push-EAX
+173     # . . call
+174     e8/call  check-ints-equal/disp32
+175     # . . discard args
+176     81          0/subop/add         3/mod/direct    4/rm32/ESP    .           .             .           .           .               0xc/imm32         # add to ESP
+177     c3/return
+178 
+179 test-compare-kernel-string-with-inequal-array:
+180     # EAX = kernel-string-equal?(_test-Abc-kernel-string, "Adc")
+181     # . . push args
+182     68/push  "Adc"/imm32
+183     68/push  _test-Abc-kernel-string/imm32
+184     # . . call
+185     e8/call  kernel-string-equal?/disp32
+186     # . . discard args
+187     81          0/subop/add         3/mod/direct    4/rm32/ESP    .           .             .           .           .               8/imm32           # add to ESP
+188     # check-ints-equal(EAX, 0, msg)
+189     # . . push args
+190     68/push  "F - test-compare-kernel-string-with-equal-array"/imm32
+191     68/push  0/imm32/false
+192     50/push-EAX
+193     # . . call
+194     e8/call  check-ints-equal/disp32
+195     # . . discard args
+196     81          0/subop/add         3/mod/direct    4/rm32/ESP    .           .             .           .           .               0xc/imm32         # add to ESP
+197     c3/return
+198 
+199 test-compare-kernel-string-with-empty-array:
+200     # EAX = kernel-string-equal?(_test-Abc-kernel-string, "")
+201     # . . push args
+202     68/push  ""/imm32
+203     68/push  _test-Abc-kernel-string/imm32
+204     # . . call
+205     e8/call  kernel-string-equal?/disp32
+206     # . . discard args
+207     81          0/subop/add         3/mod/direct    4/rm32/ESP    .           .             .           .           .               8/imm32           # add to ESP
+208     # check-ints-equal(EAX, 0, msg)
+209     # . . push args
+210     68/push  "F - test-compare-kernel-string-with-equal-array"/imm32
+211     68/push  0/imm32/false
+212     50/push-EAX
+213     # . . call
+214     e8/call  check-ints-equal/disp32
+215     # . . discard args
+216     81          0/subop/add         3/mod/direct    4/rm32/ESP    .           .             .           .           .               0xc/imm32         # add to ESP
+217     c3/return
+218 
+219 test-compare-kernel-string-with-shorter-array:
+220     # EAX = kernel-string-equal?(_test-Abc-kernel-string, "Ab")
+221     # . . push args
+222     68/push  "Ab"/imm32
+223     68/push  _test-Abc-kernel-string/imm32
+224     # . . call
+225     e8/call  kernel-string-equal?/disp32
+226     # . . discard args
+227     81          0/subop/add         3/mod/direct    4/rm32/ESP    .           .             .           .           .               8/imm32           # add to ESP
+228     # check-ints-equal(EAX, 0, msg)
+229     # . . push args
+230     68/push  "F - test-compare-kernel-string-with-shorter-array"/imm32
+231     68/push  0/imm32/false
+232     50/push-EAX
+233     # . . call
+234     e8/call  check-ints-equal/disp32
+235     # . . discard args
+236     81          0/subop/add         3/mod/direct    4/rm32/ESP    .           .             .           .           .               0xc/imm32         # add to ESP
+237     c3/return
+238 
+239 test-compare-kernel-string-with-longer-array:
+240     # EAX = kernel-string-equal?(_test-Abc-kernel-string, "Abcd")
+241     # . . push args
+242     68/push  "Abcd"/imm32
+243     68/push  _test-Abc-kernel-string/imm32
+244     # . . call
+245     e8/call  kernel-string-equal?/disp32
+246     # . . discard args
+247     81          0/subop/add         3/mod/direct    4/rm32/ESP    .           .             .           .           .               8/imm32           # add to ESP
+248     # check-ints-equal(EAX, 0, msg)
+249     # . . push args
+250     68/push  "F - test-compare-kernel-string-with-longer-array"/imm32
+251     68/push  0/imm32/false
+252     50/push-EAX
+253     # . . call
+254     e8/call  check-ints-equal/disp32
+255     # . . discard args
+256     81          0/subop/add         3/mod/direct    4/rm32/ESP    .           .             .           .           .               0xc/imm32         # add to ESP
+257     c3/return
+258 
+259 == data
+260 
+261 Null-kernel-string:
+262     00/null
+263 
+264 _test-Abc-kernel-string:
+265     41/A 62/b 63/c 00/null
+266 
+267 # . . vim:nowrap:textwidth=0
+
+ + + -- cgit 1.4.1-2-gfad0