Mu - 075print-int-decimal.subx

From 1afc882890399d70926a09036f4e66c33b3972cc Mon Sep 17 00:00:00 2001 From: Kartik Agaram Date: Mon, 29 Jun 2020 18:31:17 -0700 Subject: 6596 --- html/075write-int-decimal.subx.html | 445 ++++++++++++++++++++++++++++++++++++ 1 file changed, 445 insertions(+) create mode 100644 html/075write-int-decimal.subx.html (limited to 'html/075write-int-decimal.subx.html') diff --git a/html/075write-int-decimal.subx.html b/html/075write-int-decimal.subx.html new file mode 100644 index 00000000..4227ba21 --- /dev/null +++ b/html/075write-int-decimal.subx.html @@ -0,0 +1,445 @@ + + + + +Mu - 075print-int-decimal.subx + + + + + + + + + + +https://github.com/akkartik/mu/blob/master/075print-int-decimal.subx +
+  1 # Helper to print an int32 in decimal.
+  2 
+  3 == code
+  4 #   instruction                     effective address                                                   register    displacement    immediate
+  5 # . op          subop               mod             rm32          base        index         scale       r32
+  6 # . 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
+  7 
+  8 print-int32-decimal:  # out: (addr stream byte), n: int32
+  9     # works by generating characters from lowest to highest and pushing them
+ 10     # to the stack, before popping them one by one into the stream
+ 11     #
+ 12     # pseudocode:
+ 13     #   push sentinel
+ 14     #   eax = abs(n)
+ 15     #   while true
+ 16     #     sign-extend eax into edx
+ 17     #     eax, edx = eax/10, eax%10
+ 18     #     edx += '0'
+ 19     #     push edx
+ 20     #     if (eax == 0) break
+ 21     #   if n < 0
+ 22     #     push '-'
+ 23     #   w = out->write
+ 24     #   curr = &out->data[out->write]
+ 25     #   max = &out->data[out->size]
+ 26     #   while true
+ 27     #     pop into eax
+ 28     #     if (eax == sentinel) break
+ 29     #     if (curr >= max) abort
+ 30     #     *curr = AL
+ 31     #     ++curr
+ 32     #     ++w
+ 33     #   out->write = w
+ 34     # (based on K&R itoa: https://en.wikibooks.org/wiki/C_Programming/stdlib.h/itoa)
+ 35     # (this pseudocode contains registers because operations like division
+ 36     # require specific registers in x86)
+ 37     #
+ 38     # . prologue
+ 39     55/push-ebp
+ 40     89/copy                         3/mod/direct    5/rm32/ebp    .           .             .           4/r32/esp   .               .                 # copy esp to ebp
+ 41     # . save registers
+ 42     50/push-eax
+ 43     51/push-ecx
+ 44     52/push-edx
+ 45     53/push-ebx
+ 46     57/push-edi
+ 47     # const ten/ecx = 10
+ 48     b9/copy-to-ecx  0xa/imm32
+ 49     # push sentinel
+ 50     68/push  0/imm32/sentinel
+ 51     # var eax: int = abs(n)
+ 52     8b/copy                         1/mod/*+disp8   5/rm32/ebp    .           .             .           0/r32/eax   0xc/disp8       .                 # copy *(ebp+12) to eax
+ 53     3d/compare-eax-with  0/imm32
+ 54     7d/jump-if->=  $print-int32-decimal:read-loop/disp8
+ 55 $print-int32-decimal:negative:
+ 56     f7          3/subop/negate      3/mod/direct    0/rm32/eax    .           .             .           .           .               .                 # negate eax
+ 57 $print-int32-decimal:read-loop:
+ 58     # eax, edx = eax / 10, eax % 10
+ 59     99/sign-extend-eax-into-edx
+ 60     f7          7/subop/idiv        3/mod/direct    1/rm32/ecx    .           .             .           .           .               .                 # divide edx:eax by ecx, storing quotient in eax and remainder in edx
+ 61     # edx += '0'
+ 62     81          0/subop/add         3/mod/direct    2/rm32/edx    .           .             .           .           .               0x30/imm32        # add to edx
+ 63     # push edx
+ 64     52/push-edx
+ 65     # if (eax == 0) break
+ 66     3d/compare-eax-and  0/imm32
+ 67     7f/jump-if->  $print-int32-decimal:read-loop/disp8
+ 68 $print-int32-decimal:read-break:
+ 69     # if (n < 0) push('-')
+ 70     81          7/subop/compare     1/mod/*+disp8   5/rm32/ebp    .           .             .           .           0xc/disp8       0/imm32           # compare *(ebp+12)
+ 71     7d/jump-if->=  $print-int32-decimal:write/disp8
+ 72 $print-int32-decimal:push-negative:
+ 73     68/push  0x2d/imm32/-
+ 74 $print-int32-decimal:write:
+ 75     # edi = out
+ 76     8b/copy                         1/mod/*+disp8   5/rm32/ebp    .           .             .           7/r32/edi   8/disp8         .                 # copy *(ebp+8) to edi
+ 77     # var w/edx: int = out->write
+ 78     8b/copy                         0/mod/indirect  7/rm32/edi    .           .             .           2/r32/edx   .               .                 # copy *edi to edx
+ 79     # var curr/ecx: (addr byte) = &out->data[out->write]
+ 80     8d/copy-address                 1/mod/*+disp8   4/rm32/sib    7/base/edi  2/index/edx   .           1/r32/ecx   0xc/disp8       .                 # copy ebx+edx+12 to ecx
+ 81     # var max/ebx: (addr byte) = &out->data[out->size]
+ 82     8b/copy                         1/mod/*+disp8   7/rm32/edi    .           .             .           3/r32/ebx   8/disp8         .                 # copy *(edi+8) to ebx
+ 83     8d/copy-address                 1/mod/*+disp8   4/rm32/sib    7/base/edi  3/index/ebx   .           3/r32/ebx   0xc/disp8       .                 # copy edi+ebx+12 to ebx
+ 84 $print-int32-decimal:write-loop:
+ 85     # pop into eax
+ 86     58/pop-to-eax
+ 87     # if (eax == sentinel) break
+ 88     3d/compare-eax-and  0/imm32/sentinel
+ 89     74/jump-if-=  $print-int32-decimal:write-break/disp8
+ 90     # if (curr >= max) abort
+ 91     39/compare                      3/mod/direct    1/rm32/ecx    .           .             .           3/r32/ebx   .               .                 # compare ecx with ebx
+ 92     73/jump-if-addr>=  $print-int32-decimal:abort/disp8
+ 93 $print-int32-decimal:write-char:
+ 94     # *curr = AL
+ 95     88/copy-byte                    0/mod/indirect  1/rm32/ecx    .           .             .           0/r32/AL    .               .                 # copy AL to byte at *ecx
+ 96     # ++curr
+ 97     41/increment-ecx
+ 98     # ++w
+ 99     42/increment-edx
+100     eb/jump  $print-int32-decimal:write-loop/disp8
+101 $print-int32-decimal:write-break:
+102     # out->write = w
+103     89/copy                         0/mod/indirect  7/rm32/edi    .           .             .           2/r32/edx   .               .                 # copy edx to *edi
+104 $print-int32-decimal:end:
+105     # . restore registers
+106     5f/pop-to-edi
+107     5b/pop-to-ebx
+108     5a/pop-to-edx
+109     59/pop-to-ecx
+110     58/pop-to-eax
+111     # . epilogue
+112     89/copy                         3/mod/direct    4/rm32/esp    .           .             .           5/r32/ebp   .               .                 # copy ebp to esp
+113     5d/pop-to-ebp
+114     c3/return
+115 
+116 $print-int32-decimal:abort:
+117     # . _write(2/stderr, error)
+118     # . . push args
+119     68/push  "print-int32-decimal: out of space\n"/imm32
+120     68/push  2/imm32/stderr
+121     # . . call
+122     e8/call  _write/disp32
+123     # . . discard args
+124     81          0/subop/add         3/mod/direct    4/rm32/esp    .           .             .           .           .               8/imm32           # add to esp
+125     # . syscall(exit, 1)
+126     bb/copy-to-ebx  1/imm32
+127     e8/call  syscall_exit/disp32
+128     # never gets here
+129 
+130 test-print-int32-decimal:
+131     # - check that a single-digit number converts correctly
+132     # setup
+133     # . clear-stream(_test-stream)
+134     # . . push args
+135     68/push  _test-stream/imm32
+136     # . . call
+137     e8/call  clear-stream/disp32
+138     # . . discard args
+139     81          0/subop/add         3/mod/direct    4/rm32/esp    .           .             .           .           .               4/imm32           # add to esp
+140     # print-int32-decimal(_test-stream, 9)
+141     # . . push args
+142     68/push  9/imm32
+143     68/push  _test-stream/imm32
+144     # . . call
+145     e8/call  print-int32-decimal/disp32
+146     # . . discard args
+147     81          0/subop/add         3/mod/direct    4/rm32/esp    .           .             .           .           .               8/imm32           # add to esp
+148     # check-stream-equal(_test-stream, "9", msg)
+149     # . . push args
+150     68/push  "F - test-print-int32-decimal"/imm32
+151     68/push  "9"/imm32
+152     68/push  _test-stream/imm32
+153     # . . call
+154     e8/call  check-stream-equal/disp32
+155     # . . discard args
+156     81          0/subop/add         3/mod/direct    4/rm32/esp    .           .             .           .           .               0xc/imm32         # add to esp
+157     # . end
+158     c3/return
+159 
+160 test-print-int32-decimal-zero:
+161     # - check that 0 converts correctly
+162     # setup
+163     # . clear-stream(_test-stream)
+164     # . . push args
+165     68/push  _test-stream/imm32
+166     # . . call
+167     e8/call  clear-stream/disp32
+168     # . . discard args
+169     81          0/subop/add         3/mod/direct    4/rm32/esp    .           .             .           .           .               4/imm32           # add to esp
+170     # print-int32-decimal(_test-stream, 0)
+171     # . . push args
+172     68/push  0/imm32
+173     68/push  _test-stream/imm32
+174     # . . call
+175     e8/call  print-int32-decimal/disp32
+176     # . . discard args
+177     81          0/subop/add         3/mod/direct    4/rm32/esp    .           .             .           .           .               8/imm32           # add to esp
+178     # check-stream-equal(_test-stream, "0", msg)
+179     # . . push args
+180     68/push  "F - test-print-int32-decimal-zero"/imm32
+181     68/push  "0"/imm32
+182     68/push  _test-stream/imm32
+183     # . . call
+184     e8/call  check-stream-equal/disp32
+185     # . . discard args
+186     81          0/subop/add         3/mod/direct    4/rm32/esp    .           .             .           .           .               0xc/imm32         # add to esp
+187     # . end
+188     c3/return
+189 
+190 test-print-int32-decimal-multiple-digits:
+191     # - check that a multi-digit number converts correctly
+192     # setup
+193     # . clear-stream(_test-stream)
+194     # . . push args
+195     68/push  _test-stream/imm32
+196     # . . call
+197     e8/call  clear-stream/disp32
+198     # . . discard args
+199     81          0/subop/add         3/mod/direct    4/rm32/esp    .           .             .           .           .               4/imm32           # add to esp
+200     # print-int32-decimal(_test-stream, 10)
+201     # . . push args
+202     68/push  0xa/imm32
+203     68/push  _test-stream/imm32
+204     # . . call
+205     e8/call  print-int32-decimal/disp32
+206     # . . discard args
+207     81          0/subop/add         3/mod/direct    4/rm32/esp    .           .             .           .           .               8/imm32           # add to esp
+208     # check-stream-equal(_test-stream, "10", msg)
+209     # . . push args
+210     68/push  "F - test-print-int32-decimal-multiple-digits"/imm32
+211     68/push  "10"/imm32
+212     68/push  _test-stream/imm32
+213     # . . call
+214     e8/call  check-stream-equal/disp32
+215     # . . discard args
+216     81          0/subop/add         3/mod/direct    4/rm32/esp    .           .             .           .           .               0xc/imm32         # add to esp
+217     # . end
+218     c3/return
+219 
+220 test-print-int32-decimal-negative:
+221     # - check that a negative single-digit number converts correctly
+222     # setup
+223     # . clear-stream(_test-stream)
+224     # . . push args
+225     68/push  _test-stream/imm32
+226     # . . call
+227     e8/call  clear-stream/disp32
+228     # . . discard args
+229     81          0/subop/add         3/mod/direct    4/rm32/esp    .           .             .           .           .               4/imm32           # add to esp
+230     # print-int32-decimal(_test-stream, -9)
+231     # . . push args
+232     68/push  -9/imm32
+233     68/push  _test-stream/imm32
+234     # . . call
+235     e8/call  print-int32-decimal/disp32
+236     # . . discard args
+237     81          0/subop/add         3/mod/direct    4/rm32/esp    .           .             .           .           .               8/imm32           # add to esp
+238 +-- 26 lines: #?     # dump _test-stream ------------------------------------------------------------------------------------------------------------------------------------------------
+264     # check-stream-equal(_test-stream, "-9", msg)
+265     # . . push args
+266     68/push  "F - test-print-int32-decimal-negative"/imm32
+267     68/push  "-9"/imm32
+268     68/push  _test-stream/imm32
+269     # . . call
+270     e8/call  check-stream-equal/disp32
+271     # . . discard args
+272     81          0/subop/add         3/mod/direct    4/rm32/esp    .           .             .           .           .               0xc/imm32         # add to esp
+273     # . end
+274     c3/return
+275 
+276 test-print-int32-decimal-negative-multiple-digits:
+277     # - check that a multi-digit number converts correctly
+278     # setup
+279     # . clear-stream(_test-stream)
+280     # . . push args
+281     68/push  _test-stream/imm32
+282     # . . call
+283     e8/call  clear-stream/disp32
+284     # . . discard args
+285     81          0/subop/add         3/mod/direct    4/rm32/esp    .           .             .           .           .               4/imm32           # add to esp
+286     # print-int32-decimal(_test-stream, -10)
+287     # . . push args
+288     68/push  -0xa/imm32
+289     68/push  _test-stream/imm32
+290     # . . call
+291     e8/call  print-int32-decimal/disp32
+292     # . . discard args
+293     81          0/subop/add         3/mod/direct    4/rm32/esp    .           .             .           .           .               8/imm32           # add to esp
+294     # check-stream-equal(_test-stream, "-10", msg)
+295     # . . push args
+296     68/push  "F - test-print-int32-decimal-negative-multiple-digits"/imm32
+297     68/push  "-10"/imm32
+298     68/push  _test-stream/imm32
+299     # . . call
+300     e8/call  check-stream-equal/disp32
+301     # . . discard args
+302     81          0/subop/add         3/mod/direct    4/rm32/esp    .           .             .           .           .               0xc/imm32         # add to esp
+303     # . end
+304     c3/return
+305 
+306 is-decimal-digit?:  # c: byte -> eax: boolean
+307     # . prologue
+308     55/push-ebp
+309     89/copy                         3/mod/direct    5/rm32/ebp    .           .             .           4/r32/esp   .               .                 # copy esp to ebp
+310     # . save registers
+311     51/push-ecx
+312     # ecx = c
+313     8b/copy                         1/mod/*+disp8   5/rm32/ebp    .           .             .           1/r32/ecx   8/disp8         .                 # copy *(ebp+8) to ecx
+314     # result = false
+315     b8/copy-to-eax  0/imm32/false
+316     # return false if c < '0'
+317     81          7/subop/compare     3/mod/direct    1/rm32/ecx    .           .             .           .           .               0x30/imm32        # compare ecx
+318     7c/jump-if-<  $is-decimal-digit?:end/disp8
+319     # return (c <= '9')
+320     81          7/subop/compare     3/mod/direct    1/rm32/ecx    .           .             .           .           .               0x39/imm32        # compare ecx
+321     7f/jump-if->  $is-decimal-digit?:end/disp8
+322 $is-decimal-digit?:true:
+323     b8/copy-to-eax  1/imm32/true
+324 $is-decimal-digit?:end:
+325     # . restore registers
+326     59/pop-to-ecx
+327     # . epilogue
+328     89/copy                         3/mod/direct    4/rm32/esp    .           .             .           5/r32/ebp   .               .                 # copy ebp to esp
+329     5d/pop-to-ebp
+330     c3/return
+331 
+332 test-is-decimal-digit-below-0:
+333     # eax = is-decimal-digit?(0x2f)
+334     # . . push args
+335     68/push  0x2f/imm32
+336     # . . call
+337     e8/call  is-decimal-digit?/disp32
+338     # . . discard args
+339     81          0/subop/add         3/mod/direct    4/rm32/esp    .           .             .           .           .               4/imm32           # add to esp
+340     # check-ints-equal(eax, 0, msg)
+341     # . . push args
+342     68/push  "F - test-is-decimal-digit-below-0"/imm32
+343     68/push  0/imm32/false
+344     50/push-eax
+345     # . . call
+346     e8/call  check-ints-equal/disp32
+347     # . . discard args
+348     81          0/subop/add         3/mod/direct    4/rm32/esp    .           .             .           .           .               0xc/imm32         # add to esp
+349     c3/return
+350 
+351 test-is-decimal-digit-0-to-9:
+352     # eax = is-decimal-digit?(0x30)
+353     # . . push args
+354     68/push  0x30/imm32
+355     # . . call
+356     e8/call  is-decimal-digit?/disp32
+357     # . . discard args
+358     81          0/subop/add         3/mod/direct    4/rm32/esp    .           .             .           .           .               4/imm32           # add to esp
+359     # check-ints-equal(eax, 1, msg)
+360     # . . push args
+361     68/push  "F - test-is-decimal-digit-at-0"/imm32
+362     68/push  1/imm32/true
+363     50/push-eax
+364     # . . call
+365     e8/call  check-ints-equal/disp32
+366     # . . discard args
+367     81          0/subop/add         3/mod/direct    4/rm32/esp    .           .             .           .           .               0xc/imm32         # add to esp
+368     # eax = is-decimal-digit?(0x39)
+369     # . . push args
+370     68/push  0x39/imm32
+371     # . . call
+372     e8/call  is-decimal-digit?/disp32
+373     # . . discard args
+374     81          0/subop/add         3/mod/direct    4/rm32/esp    .           .             .           .           .               4/imm32           # add to esp
+375     # check-ints-equal(eax, 1, msg)
+376     # . . push args
+377     68/push  "F - test-is-decimal-digit-at-9"/imm32
+378     68/push  1/imm32/true
+379     50/push-eax
+380     # . . call
+381     e8/call  check-ints-equal/disp32
+382     # . . discard args
+383     81          0/subop/add         3/mod/direct    4/rm32/esp    .           .             .           .           .               0xc/imm32         # add to esp
+384     c3/return
+385 
+386 test-is-decimal-digit-above-9:
+387     # eax = is-decimal-digit?(0x3a)
+388     # . . push args
+389     68/push  0x3a/imm32
+390     # . . call
+391     e8/call  is-decimal-digit?/disp32
+392     # . . discard args
+393     81          0/subop/add         3/mod/direct    4/rm32/esp    .           .             .           .           .               4/imm32           # add to esp
+394     # check-ints-equal(eax, 0, msg)
+395     # . . push args
+396     68/push  "F - test-is-decimal-digit-above-9"/imm32
+397     68/push  0/imm32/false
+398     50/push-eax
+399     # . . call
+400     e8/call  check-ints-equal/disp32
+401     # . . discard args
+402     81          0/subop/add         3/mod/direct    4/rm32/esp    .           .             .           .           .               0xc/imm32         # add to esp
+403     c3/return
+404 
+405 # . . vim:nowrap:textwidth=0
+
+ + + -- cgit 1.4.1-2-gfad0