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/examples/ex10.subx.html | 135 +++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 135 insertions(+) create mode 100644 html/examples/ex10.subx.html (limited to 'html/examples/ex10.subx.html') diff --git a/html/examples/ex10.subx.html b/html/examples/ex10.subx.html new file mode 100644 index 00000000..4d84ab28 --- /dev/null +++ b/html/examples/ex10.subx.html @@ -0,0 +1,135 @@ + + + + +Mu - subx/examples/ex10.subx + + + + + + + + + + +https://github.com/akkartik/mu/blob/master/subx/examples/ex10.subx +
+ 1 # String comparison: return 1 iff the two args passed in at the commandline are equal.
+ 2 #
+ 3 # To run (from the subx directory):
+ 4 #   $ ./subx translate examples/ex10.subx -o examples/ex10
+ 5 #   $ ./subx run examples/ex10 abc abd
+ 6 # Expected result:
+ 7 #   $ echo $?
+ 8 #   0  # false
+ 9 
+10 == code 0x09000000
+11 #   instruction                     effective address                                                   register    displacement    immediate
+12 # . op          subop               mod             rm32          base        index         scale       r32
+13 # . 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
+14 
+15 Entry:  # return argv-equal(argv[1], argv[2])
+16 #       At the start of a SubX program:
+17 #         argc: *ESP
+18 #         argv[0]: *(ESP+4)
+19 #         argv[1]: *(ESP+8)
+20 #         ...
+21     # . prolog
+22     89/copy                         3/mod/direct    5/rm32/EBP    .           .             .           4/r32/ESP   .               .                 # copy ESP to EBP
+23     # argv-equal(argv[1], argv[2])
+24     # . . push argv[2]
+25     ff          6/subop/push        1/mod/*+disp8   5/rm32/EBP    .           .             .           .           0xc/disp8       .                 # push *(EBP+12)
+26     # . . push argv[1]
+27     ff          6/subop/push        1/mod/*+disp8   5/rm32/EBP    .           .             .           .           8/disp8         .                 # push *(EBP+8)
+28     # . . call
+29     e8/call argv-equal/disp32
+30     # syscall(exit, EAX)
+31     89/copy                         3/mod/direct    3/rm32/EBX    .           .             .           0/r32/EAX   .               .                 # copy EAX to EBX
+32     b8/copy-to-EAX  1/imm32/exit
+33     cd/syscall  0x80/imm8
+34 
+35 # compare two null-terminated ascii strings
+36 # reason for the name: the only place we should have null-terminated ascii strings is from commandline args
+37 argv-equal:  # (s1, s2) : null-terminated ascii strings -> EAX : boolean
+38     # initialize s1 (ECX) and s2 (EDX)
+39     8b/copy                         1/mod/*+disp8   4/rm32/sib    4/base/ESP  4/index/none  .           1/r32/ECX   4/disp8         .                 # copy *(ESP+4) to ECX
+40     8b/copy                         1/mod/*+disp8   4/rm32/sib    4/base/ESP  4/index/none  .           2/r32/EDX   8/disp8         .                 # copy *(ESP+8) to EDX
+41 $argv-equal:loop:
+42     # c1/EAX, c2/EBX = *s1, *s2
+43     b8/copy-to-EAX  0/imm32
+44     8a/copy-byte                    0/mod/indirect  1/rm32/ECX    .           .             .           0/r32/AL    .               .                 # copy byte at *ECX to AL
+45     bb/copy-to-EBX  0/imm32
+46     8a/copy-byte                    0/mod/indirect  2/rm32/EDX    .           .             .           3/r32/BL    .               .                 # copy byte at *EDX to BL
+47     # if (c1 == 0) break
+48     3d/compare-EAX-and  0/imm32
+49     74/jump-if-equal  $argv-equal:break/disp8
+50     # if (c1 != c2) return false
+51     39/compare                      3/mod/direct    0/rm32/EAX    .           .             .           3/r32/EBX   .               .                 # compare EAX and EBX
+52     75/jump-if-not-equal  $argv-equal:false/disp8
+53     # ++s1, ++s2
+54     41/increment-ECX
+55     42/increment-EDX
+56     # end while
+57     eb/jump  $argv-equal:loop/disp8
+58 $argv-equal:break:
+59     # if (c2 == 0) return true
+60     81          7/subop/compare     3/mod/direct    3/rm32/EBX    .           .             .           .           .               0/imm32           # compare EBX
+61     75/jump-if-not-equal  $argv-equal:false/disp8
+62 $argv-equal:success:
+63     b8/copy-to-EAX  1/imm32
+64     c3/return
+65     # return false
+66 $argv-equal:false:
+67     b8/copy-to-EAX  0/imm32
+68     c3/return
+69 
+70 == data 0x0a000000
+71 
+72 # . . vim:nowrap:textwidth=0
+
+ + + -- cgit 1.4.1-2-gfad0