From 0f73127ef1eba0a8ea814c26115523da3590ffe2 Mon Sep 17 00:00:00 2001 From: Kartik Agaram Date: Fri, 22 Jan 2021 23:29:04 -0800 Subject: 7547 - baremetal: rpn calculator Still in progress. Known bugs: * Cursor management is broken. Every line currently seems to leave behind a shadow cursor. * No shift-key support yet, which means no addition or multiplication. (This app doesn't have division yet.) --- baremetal/105string-equal.subx | 256 +++++++++++++++++++++++++++++++++++++++++ 1 file changed, 256 insertions(+) create mode 100644 baremetal/105string-equal.subx (limited to 'baremetal/105string-equal.subx') diff --git a/baremetal/105string-equal.subx b/baremetal/105string-equal.subx new file mode 100644 index 00000000..2289e514 --- /dev/null +++ b/baremetal/105string-equal.subx @@ -0,0 +1,256 @@ +# Comparing 'regular' size-prefixed strings. + +== code +# instruction effective address register displacement immediate +# . op subop mod rm32 base index scale r32 +# . 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 + +string-equal?: # s: (addr array byte), benchmark: (addr array byte) -> result/eax: boolean + # pseudocode: + # if (s->size != benchmark->size) return false + # return string-starts-with?(s, benchmark) + # + # . prologue + 55/push-ebp + 89/copy 3/mod/direct 5/rm32/ebp . . . 4/r32/esp . . # copy esp to ebp + # . save registers + 51/push-ecx + 56/push-esi + 57/push-edi + # esi = s + 8b/copy 1/mod/*+disp8 5/rm32/ebp . . . 6/r32/esi 8/disp8 . # copy *(ebp+8) to esi + # edi = benchmark + 8b/copy 1/mod/*+disp8 5/rm32/ebp . . . 7/r32/edi 0xc/disp8 . # copy *(ebp+12) to edi + # ecx = s->size + 8b/copy 0/mod/indirect 6/rm32/esi . . . 1/r32/ecx . . # copy *esi to ecx +$string-equal?:sizes: + # if (ecx != benchmark->size) return false + 39/compare 0/mod/indirect 7/rm32/edi . . . 1/r32/ecx . . # compare *edi and ecx + b8/copy-to-eax 0/imm32/false + 75/jump-if-!= $string-equal?:end/disp8 +$string-equal?:contents: + # string-starts-with?(s, benchmark) + # . . push args + ff 6/subop/push 1/mod/*+disp8 5/rm32/ebp . . . . 0xc/disp8 . # push *(ebp+12) + ff 6/subop/push 1/mod/*+disp8 5/rm32/ebp . . . . 8/disp8 . # push *(ebp+8) + # . . call + e8/call string-starts-with?/disp32 + # . . discard args + 81 0/subop/add 3/mod/direct 4/rm32/esp . . . . . 8/imm32 # add to esp +$string-equal?:end: + # . restore registers + 5f/pop-to-edi + 5e/pop-to-esi + 59/pop-to-ecx + # . epilogue + 89/copy 3/mod/direct 4/rm32/esp . . . 5/r32/ebp . . # copy ebp to esp + 5d/pop-to-ebp + c3/return + +string-starts-with?: # s: (addr array byte), benchmark: (addr array byte) -> result/eax: boolean + # pseudocode: + # if (s->size < benchmark->size) return false + # currs = s->data + # currb = benchmark->data + # maxb = &benchmark->data[benchmark->size] + # while currb < maxb + # c1 = *currs + # c2 = *currb + # if (c1 != c2) return false + # ++currs, ++currb + # return true + # + # registers: + # currs: esi + # maxs: ecx + # currb: edi + # c1: eax + # c2: ebx + # + # . prologue + 55/push-ebp + 89/copy 3/mod/direct 5/rm32/ebp . . . 4/r32/esp . . # copy esp to ebp + # . save registers + 51/push-ecx + 52/push-edx + 56/push-esi + 57/push-edi + # esi = s + 8b/copy 1/mod/*+disp8 5/rm32/ebp . . . 6/r32/esi 8/disp8 . # copy *(ebp+8) to esi + # edi = benchmark + 8b/copy 1/mod/*+disp8 5/rm32/ebp . . . 7/r32/edi 0xc/disp8 . # copy *(ebp+12) to edi + # var bsize/ecx: int = benchmark->size + 8b/copy 0/mod/indirect 7/rm32/edi . . . 1/r32/ecx . . # copy *edi to ecx +$string-starts-with?:sizes: + # if (s->size < bsize) return false + 39/compare 0/mod/indirect 6/rm32/esi . . . 1/r32/ecx . . # compare *esi with ecx + 7c/jump-if-< $string-starts-with?:false/disp8 + # var currs/esi: (addr byte) = s->data + 81 0/subop/add 3/mod/direct 6/rm32/esi . . . . . 4/imm32 # add to esi + # var currb/edi: (addr byte) = benchmark->data + 81 0/subop/add 3/mod/direct 7/rm32/edi . . . . . 4/imm32 # add to edi + # var maxb/ecx: (addr byte) = &benchmark->data[benchmark->size] + 01/add 3/mod/direct 1/rm32/ecx . . . 7/r32/edi . . # add edi to ecx + # var c1/eax: byte = 0 + 31/xor 3/mod/direct 0/rm32/eax . . . 0/r32/eax . . # clear eax + # var c2/edx: byte = 0 + 31/xor 3/mod/direct 2/rm32/edx . . . 2/r32/edx . . # clear edx +$string-starts-with?:loop: + # if (currs >= maxs) return true + 39/compare 3/mod/direct 7/rm32/edi . . . 1/r32/ecx . . # compare edi with ecx + 73/jump-if-addr>= $string-starts-with?:true/disp8 + # c1 = *currs + 8a/copy-byte 0/mod/indirect 6/rm32/esi . . . 0/r32/AL . . # copy byte at *esi to AL + # c2 = *currb + 8a/copy-byte 0/mod/indirect 7/rm32/edi . . . 2/r32/DL . . # copy byte at *edi to DL + # if (c1 != c2) return false + 39/compare 3/mod/direct 0/rm32/eax . . . 2/r32/edx . . # compare eax and edx + 75/jump-if-!= $string-starts-with?:false/disp8 + # ++currs + 46/increment-esi + # ++currb + 47/increment-edi + eb/jump $string-starts-with?:loop/disp8 +$string-starts-with?:true: + b8/copy-to-eax 1/imm32 + eb/jump $string-starts-with?:end/disp8 +$string-starts-with?:false: + b8/copy-to-eax 0/imm32 +$string-starts-with?:end: + # . restore registers + 5f/pop-to-edi + 5e/pop-to-esi + 5a/pop-to-edx + 59/pop-to-ecx + # . epilogue + 89/copy 3/mod/direct 4/rm32/esp . . . 5/r32/ebp . . # copy ebp to esp + 5d/pop-to-ebp + c3/return + +# - tests + +test-compare-empty-with-empty-string: + # eax = string-equal?("", "") + # . . push args + 68/push ""/imm32 + 68/push ""/imm32 + # . . call + e8/call string-equal?/disp32 + # . . discard args + 81 0/subop/add 3/mod/direct 4/rm32/esp . . . . . 8/imm32 # add to esp + # check-ints-equal(eax, 1, msg) + # . . push args + 68/push "F - test-compare-empty-with-empty-string"/imm32 + 68/push 1/imm32/true + 50/push-eax + # . . call + e8/call check-ints-equal/disp32 + # . . discard args + 81 0/subop/add 3/mod/direct 4/rm32/esp . . . . . 0xc/imm32 # add to esp + c3/return + +test-compare-empty-with-non-empty-string: # also checks size-mismatch code path + # eax = string-equal?("", "Abc") + # . . push args + 68/push "Abc"/imm32 + 68/push ""/imm32 + # . . call + e8/call string-equal?/disp32 + # . . discard args + 81 0/subop/add 3/mod/direct 4/rm32/esp . . . . . 8/imm32 # add to esp + # check-ints-equal(eax, 0, msg) + # . . push args + 68/push "F - test-compare-empty-with-non-empty-string"/imm32 + 68/push 0/imm32/false + 50/push-eax + # . . call + e8/call check-ints-equal/disp32 + # . . discard args + 81 0/subop/add 3/mod/direct 4/rm32/esp . . . . . 0xc/imm32 # add to esp + c3/return + +test-compare-equal-strings: + # eax = string-equal?("Abc", "Abc") + # . . push args + 68/push "Abc"/imm32 + 68/push "Abc"/imm32 + # . . call + e8/call string-equal?/disp32 + # . . discard args + 81 0/subop/add 3/mod/direct 4/rm32/esp . . . . . 8/imm32 # add to esp + # check-ints-equal(eax, 1, msg) + # . . push args + 68/push "F - test-compare-equal-strings"/imm32 + 68/push 1/imm32/true + 50/push-eax + # . . call + e8/call check-ints-equal/disp32 + # . . discard args + 81 0/subop/add 3/mod/direct 4/rm32/esp . . . . . 0xc/imm32 # add to esp + c3/return + +test-compare-inequal-strings-equal-sizes: + # eax = string-equal?("Abc", "Adc") + # . . push args + 68/push "Adc"/imm32 + 68/push "Abc"/imm32 + # . . call + e8/call string-equal?/disp32 + # . . discard args + 81 0/subop/add 3/mod/direct 4/rm32/esp . . . . . 8/imm32 # add to esp + # check-ints-equal(eax, 0, msg) + # . . push args + 68/push "F - test-compare-inequal-strings-equal-sizes"/imm32 + 68/push 0/imm32/false + 50/push-eax + # . . call + e8/call check-ints-equal/disp32 + # . . discard args + 81 0/subop/add 3/mod/direct 4/rm32/esp . . . . . 0xc/imm32 # add to esp + c3/return + +# helper for later tests +check-strings-equal: # s: (addr array byte), expected: (addr array byte), msg: (addr array byte) + # . prologue + 55/push-ebp + 89/copy 3/mod/direct 5/rm32/ebp . . . 4/r32/esp . . # copy esp to ebp + # . save registers + 50/push-eax + # var eax: boolean = string-equal?(s, expected) + # . . push args + ff 6/subop/push 1/mod/*+disp8 5/rm32/ebp . . . . 0xc/disp8 . # push *(ebp+12) + ff 6/subop/push 1/mod/*+disp8 5/rm32/ebp . . . . 8/disp8 . # push *(ebp+8) + # . . call + e8/call string-equal?/disp32 + # . . discard args + 81 0/subop/add 3/mod/direct 4/rm32/esp . . . . . 8/imm32 # add to esp + # check-ints-equal(eax, 1, msg) + # . . push args + ff 6/subop/push 1/mod/*+disp8 5/rm32/ebp . . . . 0x10/disp8 . # push *(ebp+16) + 68/push 1/imm32 + 50/push-eax + # . . call + e8/call check-ints-equal/disp32 + # . . discard args + 81 0/subop/add 3/mod/direct 4/rm32/esp . . . . . 0xc/imm32 # add to esp +$check-strings-equal:end: + # . restore registers + 58/pop-to-eax + # . epilogue + 89/copy 3/mod/direct 4/rm32/esp . . . 5/r32/ebp . . # copy ebp to esp + 5d/pop-to-ebp + c3/return + +# test the helper +test-check-strings-equal: + # check-strings-equal("Abc", "Abc") + # . . push args + 68/push "Abc"/imm32 + 68/push "Abc"/imm32 + # . . call + e8/call check-strings-equal/disp32 + # . . discard args + 81 0/subop/add 3/mod/direct 4/rm32/esp . . . . . 8/imm32 # add to esp + c3/return + +# . . vim:nowrap:textwidth=0 -- cgit 1.4.1-2-gfad0