diff options
Diffstat (limited to 'html/subx/066allocate.subx.html')
| -rw-r--r-- | html/subx/066allocate.subx.html | 57 |
1 files changed, 56 insertions, 1 deletions
diff --git a/html/subx/066allocate.subx.html b/html/subx/066allocate.subx.html index 9cae149f..74be6f73 100644 --- a/html/subx/066allocate.subx.html +++ b/html/subx/066allocate.subx.html @@ -209,7 +209,62 @@ if ('onhashchange' in window) { <span id="L149" class="LineNr">149 </span> 5d/pop-to-EBP <span id="L150" class="LineNr">150 </span> c3/return <span id="L151" class="LineNr">151 </span> -<span id="L152" class="LineNr">152 </span><span class="subxS2Comment"># . . vim:nowrap:textwidth=0</span> +<span id="L152" class="LineNr">152 </span><span class="subxComment"># helper: create a nested allocation descriptor (useful for tests)</span> +<span id="L153" class="LineNr">153 </span><span class="subxFunction">allocate-region</span>: <span class="subxComment"># ad : (address allocation-descriptor), n : int -> new-ad : (address allocation-descriptor)</span> +<span id="L154" class="LineNr">154 </span> <span class="subxS1Comment"># . prolog</span> +<span id="L155" class="LineNr">155 </span> 55/push-EBP +<span id="L156" class="LineNr">156 </span> 89/copy 3/mod/direct 5/rm32/EBP <span class="Normal"> . </span> <span class="Normal"> . </span> <span class="Normal"> . </span> 4/r32/ESP <span class="Normal"> . </span> <span class="Normal"> . </span> <span class="subxComment"># copy ESP to EBP</span> +<span id="L157" class="LineNr">157 </span> <span class="subxS1Comment"># . save registers</span> +<span id="L158" class="LineNr">158 </span> 51/push-ECX +<span id="L159" class="LineNr">159 </span> <span class="subxComment"># EAX = allocate(ad, n)</span> +<span id="L160" class="LineNr">160 </span> <span class="subxS2Comment"># . . push args</span> +<span id="L161" class="LineNr">161 </span> ff 6/subop/push 1/mod/*+disp8 5/rm32/EBP <span class="Normal"> . </span> <span class="Normal"> . </span> <span class="Normal"> . </span> <span class="Normal"> . </span> 0xc/disp8 <span class="Normal"> . </span> <span class="subxComment"># push *(EBP+12)</span> +<span id="L162" class="LineNr">162 </span> ff 6/subop/push 1/mod/*+disp8 5/rm32/EBP <span class="Normal"> . </span> <span class="Normal"> . </span> <span class="Normal"> . </span> <span class="Normal"> . </span> 8/disp8 <span class="Normal"> . </span> <span class="subxComment"># push *(EBP+8)</span> +<span id="L163" class="LineNr">163 </span> <span class="subxS2Comment"># . . call</span> +<span id="L164" class="LineNr">164 </span> e8/call <a href='066allocate.subx.html#L41'>allocate</a>/disp32 +<span id="L165" class="LineNr">165 </span> <span class="subxS2Comment"># . . discard args</span> +<span id="L166" class="LineNr">166 </span> 81 0/subop/add 3/mod/direct 4/rm32/ESP <span class="Normal"> . </span> <span class="Normal"> . </span> <span class="Normal"> . </span> <span class="Normal"> . </span> <span class="Normal"> . </span> 8/imm32 <span class="subxComment"># add to ESP</span> +<span id="L167" class="LineNr">167 </span> <span class="subxComment"># if EAX == 0 abort</span> +<span id="L168" class="LineNr">168 </span> 81 7/subop/compare 3/mod/direct 0/rm32/EAX <span class="Normal"> . </span> <span class="Normal"> . </span> <span class="Normal"> . </span> <span class="Normal"> . </span> <span class="Normal"> . </span> 0/imm32 <span class="subxComment"># compare EAX</span> +<span id="L169" class="LineNr">169 </span> 74/jump-if-equal $allocate-region:abort/disp8 +<span id="L170" class="LineNr">170 </span> <span class="subxComment"># earmark 8 bytes at the start for a new allocation descriptor</span> +<span id="L171" class="LineNr">171 </span> <span class="subxS1Comment"># . *EAX = EAX + 8</span> +<span id="L172" class="LineNr">172 </span> 89/copy 3/mod/direct 1/rm32/ECX <span class="Normal"> . </span> <span class="Normal"> . </span> <span class="Normal"> . </span> 0/r32/EAX <span class="Normal"> . </span> <span class="Normal"> . </span> <span class="subxComment"># copy EAX to ECX</span> +<span id="L173" class="LineNr">173 </span> 81 0/subop/add 3/mod/direct 1/rm32/ECX <span class="Normal"> . </span> <span class="Normal"> . </span> <span class="Normal"> . </span> <span class="Normal"> . </span> <span class="Normal"> . </span> 8/imm32 <span class="subxComment"># add to ECX</span> +<span id="L174" class="LineNr">174 </span> 89/copy 0/mod/indirect 0/rm32/EAX <span class="Normal"> . </span> <span class="Normal"> . </span> <span class="Normal"> . </span> 1/r32/ECX <span class="Normal"> . </span> <span class="Normal"> . </span> <span class="subxComment"># copy ECX to *EAX</span> +<span id="L175" class="LineNr">175 </span> <span class="subxS1Comment"># . *(EAX+4) = EAX + n</span> +<span id="L176" class="LineNr">176 </span> 89/copy 3/mod/direct 1/rm32/ECX <span class="Normal"> . </span> <span class="Normal"> . </span> <span class="Normal"> . </span> 0/r32/EAX <span class="Normal"> . </span> <span class="Normal"> . </span> <span class="subxComment"># copy EAX to ECX</span> +<span id="L177" class="LineNr">177 </span> 03/add 1/mod/*+disp8 5/rm32/EBP <span class="Normal"> . </span> <span class="Normal"> . </span> <span class="Normal"> . </span> 1/r32/ECX 0xc/disp8 <span class="Normal"> . </span> <span class="subxComment"># add *(EBP+12) to ECX</span> +<span id="L178" class="LineNr">178 </span> 89/copy 1/mod/*+disp8 0/rm32/EAX <span class="Normal"> . </span> <span class="Normal"> . </span> <span class="Normal"> . </span> 1/r32/ECX 4/disp8 <span class="Normal"> . </span> <span class="subxComment"># copy ECX to *(EAX+4)</span> +<span id="L179" class="LineNr">179 </span> <span class="subxS1Comment"># . restore registers</span> +<span id="L180" class="LineNr">180 </span> 59/pop-to-ECX +<span id="L181" class="LineNr">181 </span> <span class="subxS1Comment"># . epilog</span> +<span id="L182" class="LineNr">182 </span> 89/copy 3/mod/direct 4/rm32/ESP <span class="Normal"> . </span> <span class="Normal"> . </span> <span class="Normal"> . </span> 5/r32/EBP <span class="Normal"> . </span> <span class="Normal"> . </span> <span class="subxComment"># copy EBP to ESP</span> +<span id="L183" class="LineNr">183 </span> 5d/pop-to-EBP +<span id="L184" class="LineNr">184 </span> c3/return +<span id="L185" class="LineNr">185 </span> +<span id="L186" class="LineNr">186 </span><span class="subxComment"># We could create a more general '$abort' jump target, but then we'd need to do</span> +<span id="L187" class="LineNr">187 </span><span class="subxComment"># a conditional jump followed by loading the error message and an unconditional</span> +<span id="L188" class="LineNr">188 </span><span class="subxComment"># jump. Or we'd need to unconditionally load the error message before a</span> +<span id="L189" class="LineNr">189 </span><span class="subxComment"># conditional jump, even if it's unused the vast majority of the time. This way</span> +<span id="L190" class="LineNr">190 </span><span class="subxComment"># we bloat a potentially cold segment in RAM so we can abort with a single</span> +<span id="L191" class="LineNr">191 </span><span class="subxComment"># instruction.</span> +<span id="L192" class="LineNr">192 </span><span class="Constant">$allocate-region:abort</span>: +<span id="L193" class="LineNr">193 </span> <span class="subxS1Comment"># . _write(2/stderr, error)</span> +<span id="L194" class="LineNr">194 </span> <span class="subxS2Comment"># . . push args</span> +<span id="L195" class="LineNr">195 </span> 68/push <span class="Constant">"allocate-region: failed to allocate"</span>/imm32 +<span id="L196" class="LineNr">196 </span> 68/push 2/imm32/stderr +<span id="L197" class="LineNr">197 </span> <span class="subxS2Comment"># . . call</span> +<span id="L198" class="LineNr">198 </span> e8/call <a href='050_write.subx.html#L14'>_write</a>/disp32 +<span id="L199" class="LineNr">199 </span> <span class="subxS2Comment"># . . discard args</span> +<span id="L200" class="LineNr">200 </span> 81 0/subop/add 3/mod/direct 4/rm32/ESP <span class="Normal"> . </span> <span class="Normal"> . </span> <span class="Normal"> . </span> <span class="Normal"> . </span> <span class="Normal"> . </span> 8/imm32 <span class="subxComment"># add to ESP</span> +<span id="L201" class="LineNr">201 </span> <span class="subxS1Comment"># . syscall(exit, 1)</span> +<span id="L202" class="LineNr">202 </span> bb/copy-to-EBX 1/imm32 +<span id="L203" class="LineNr">203 </span> b8/copy-to-EAX 1/imm32/exit +<span id="L204" class="LineNr">204 </span> cd/syscall 0x80/imm8 +<span id="L205" class="LineNr">205 </span> <span class="subxComment"># never gets here</span> +<span id="L206" class="LineNr">206 </span> +<span id="L207" class="LineNr">207 </span><span class="subxS2Comment"># . . vim:nowrap:textwidth=0</span> </pre> </body> </html> |