From 2b48729fd2a677ca081cec05c057d86a44664abd Mon Sep 17 00:00:00 2001 From: Kartik Agaram Date: Mon, 12 Aug 2019 23:28:48 -0700 Subject: new variant: maybe-get returns null on failure --- 078table.subx | 148 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 148 insertions(+) (limited to '078table.subx') diff --git a/078table.subx b/078table.subx index 90976b11..d172209a 100644 --- a/078table.subx +++ b/078table.subx @@ -13,6 +13,7 @@ # ------------------------+--------------------------------------------------- # abort | get get-slice # insert key | get-or-insert leaky-get-or-insert-slice +# return null | maybe-get maybe-get-slice # Some variants may take extra args. == code @@ -920,4 +921,151 @@ $test-leaky-get-or-insert-slice:end: 5d/pop-to-EBP c3/return +# if no row is found, return null (0) +maybe-get: # table : (address stream {string, _}), key : (address string), row-size : int -> EAX : (address _) + # pseudocode: + # curr = table->data + # max = &table->data[table->write] + # while curr < max + # if string-equal?(key, *curr) + # return curr+4 + # curr += row-size + # return 0 + # + # . prolog + 55/push-EBP + 89/copy 3/mod/direct 5/rm32/EBP . . . 4/r32/ESP . . # copy ESP to EBP + # . save registers + 51/push-ECX + 52/push-EDX + 56/push-ESI + # ESI = table + 8b/copy 1/mod/*+disp8 5/rm32/EBP . . . 6/r32/ESI 8/disp8 . # copy *(EBP+8) to ESI + # curr/ECX = table->data + 8d/copy-address 1/mod/*+disp8 6/rm32/ESI . . . 1/r32/ECX 0xc/disp8 . # copy ESI+12 to ECX + # max/EDX = table->data + table->write + 8b/copy 0/mod/indirect 6/rm32/ESI . . . 2/r32/EDX . . # copy *ESI to EDX + 8d/copy-address 0/mod/indirect 4/rm32/sib 1/base/ECX 2/index/EDX . 2/r32/EDX . . # copy ECX+EDX to EDX +$maybe-get:search-loop: + # if (curr >= max) return null + 39/compare 3/mod/direct 1/rm32/ECX . . . 2/r32/EDX . . # compare ECX with EDX + 73/jump-if-greater-or-equal-unsigned $maybe-get:null/disp8 + # if (string-equal?(key, *curr)) return curr+4 + # . EAX = string-equal?(key, *curr) + # . . push args + ff 6/subop/push 0/mod/indirect 1/rm32/ECX . . . . . . # push *ECX + ff 6/subop/push 1/mod/*+disp8 5/rm32/EBP . . . . 0xc/disp8 . # push *(EBP+12) + # . . call + e8/call string-equal?/disp32 + # . . discard args + 81 0/subop/add 3/mod/direct 4/rm32/ESP . . . . . 8/imm32 # add to ESP + # . if (EAX != 0) return EAX = curr+4 + 3d/compare-EAX-and 0/imm32 + 74/jump-if-equal $maybe-get:mismatch/disp8 + 8d/copy-address 1/mod/*+disp8 1/rm32/ECX . . . 0/r32/EAX 4/disp8 . # copy ECX+4 to EAX + eb/jump $maybe-get:end/disp8 +$maybe-get:mismatch: + # curr += row-size + 03/add 1/mod/*+disp8 5/rm32/EBP . . . 1/r32/ECX 0x10/disp8 . # add *(EBP+16) to ECX + # loop + eb/jump $maybe-get:search-loop/disp8 +$maybe-get:null: + b8/copy-to-EAX 0/imm32 +$maybe-get:end: + # . restore registers + 5e/pop-to-ESI + 5a/pop-to-EDX + 59/pop-to-ECX + # . epilog + 89/copy 3/mod/direct 4/rm32/ESP . . . 5/r32/EBP . . # copy EBP to ESP + 5d/pop-to-EBP + c3/return + +test-maybe-get: + # . prolog + 55/push-EBP + 89/copy 3/mod/direct 5/rm32/EBP . . . 4/r32/ESP . . # copy ESP to EBP + # - setup: create a table with one row + # var table/ECX : (address stream {string, number}) = stream(2 rows * 8 bytes) + 81 5/subop/subtract 3/mod/direct 4/rm32/ESP . . . . . 0x10/imm32 # subtract from ESP + 68/push 0x10/imm32/length + 68/push 0/imm32/read + 68/push 0/imm32/write + 89/copy 3/mod/direct 1/rm32/ECX . . . 4/r32/ESP . . # copy ESP to ECX + # EAX = get-or-insert(table, "code", 8 bytes per row) + # . . push args + 68/push 8/imm32/row-size + 68/push "code"/imm32 + 51/push-ECX + # . . call + e8/call get-or-insert/disp32 + # . . discard args + 81 0/subop/add 3/mod/direct 4/rm32/ESP . . . . . 0xc/imm32 # add to ESP +$test-maybe-get:success: + # - check for the same key, verify that it was reused + # EAX = maybe-get(table, "code", 8 bytes per row) + # . . push args + 68/push 8/imm32/row-size + 68/push "code"/imm32 + 51/push-ECX + # . . call + e8/call maybe-get/disp32 + # . . discard args + 81 0/subop/add 3/mod/direct 4/rm32/ESP . . . . . 0xc/imm32 # add to ESP + # check-ints-equal(EAX - table->data, 4, msg) + # . check-ints-equal(EAX - table, 16, msg) + # . . push args + 68/push "F - test-maybe-get/0"/imm32 + 68/push 0x10/imm32 + 29/subtract 3/mod/direct 0/rm32/EAX . . . 1/r32/ECX . . # subtract ECX from EAX + 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 + # no new row inserted + # . check-ints-equal(table->write, row-size = 8, msg) + # . . push args + 68/push "F - test-maybe-get/1"/imm32 + 68/push 8/imm32/row-size + ff 6/subop/push 0/mod/indirect 1/rm32/ECX . . . . . . # push *ECX + # . . 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-string-equal(*table->data, "code", msg) + # . . push args + 68/push "F - test-maybe-get/2"/imm32 + 68/push "code"/imm32 + ff 6/subop/push 1/mod/*+disp8 1/rm32/ECX . . . . 0xc/disp8 . # push *(ECX+12) + # . . call + e8/call check-string-equal/disp32 + # . . discard args + 81 0/subop/add 3/mod/direct 4/rm32/ESP . . . . . 0xc/imm32 # add to ESP +$test-maybe-get:failure: + # - search for a new key + # EAX = maybe-get(table, "data", 8 bytes per row) + # . . push args + 68/push 8/imm32/row-size + 68/push "data"/imm32 + 51/push-ECX + # . . call + e8/call maybe-get/disp32 + # . . discard args + 81 0/subop/add 3/mod/direct 4/rm32/ESP . . . . . 0xc/imm32 # add to ESP + # check-ints-equal(EAX, 0, msg) + # . . push args + 68/push "F - test-maybe-get/3"/imm32 + 68/push 0/imm32 + 50/push-EAX + # . . call + e8/call check-ints-equal/disp32 + # . . discard args + 81 0/subop/add 3/mod/direct 4/rm32/ESP . . . . . 0xc/imm32 # add to ESP +$test-maybe-get:end: + # . epilog + 89/copy 3/mod/direct 4/rm32/ESP . . . 5/r32/EBP . . # copy EBP to ESP + 5d/pop-to-EBP + c3/return + # . . vim:nowrap:textwidth=0 -- cgit 1.4.1-2-gfad0