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<a name="l1"></a><span class=cF5>                                                     Scoping and Linkage</span><span class=cF0>
<a name="l2"></a></span><span class=cF4>
<a name="l3"></a></span><a href="https://zeal-operating-system.github.io/ZealOS/Doc/Glossary.DD.html#l188"><span class=cF4>JIT Compile Mode</span></a><span class=cF0> makes use of the current task's hash symbol table and its parent tasks' tables.  It fetches symbols from 
<a name="l4"></a>parent tasks' tables if not found locally in the current task's table and it places new symbols in the current task's table.  
<a name="l5"></a>Conceptually, symbols are at the scope of environment variables in other operating systems.
<a name="l6"></a>
<a name="l7"></a>When a symbol is placed into a table, older symbols with ident names will be overshadowed if they exist.    Duplicates are not 
<a name="l8"></a>allowed in many cases, especially in asm blocks.  Dupicates are allowed, by design in other cases, so that you can repeatedly </span><span class=cF2>
<a name="l9"></a>#include</span><span class=cF0> the same file from the cmd line while developing it.   Or, so you can repeatedly declare a function with a standard 
<a name="l10"></a>name, like </span><span class=cF2>DrawIt()</span><span class=cF0>.  This case might occur when the </span><a href="https://zeal-operating-system.github.io/ZealOS/Doc/Glossary.DD.html#l154"><span class=cF4>System Task</span></a><span class=cF0> is starting-up loading-in many little utilities.
<a name="l11"></a>
<a name="l12"></a></span><span class=cF2>extern</span><span class=cF0> binds a new </span><a href="https://zeal-operating-system.github.io/ZealOS/Kernel/KernelA.HH.html#l828"><span class=cF4>HTT_FUN</span></a><span class=cF0> or </span><a href="https://zeal-operating-system.github.io/ZealOS/Kernel/KernelA.HH.html#l825"><span class=cF4>HTT_GLOBAL_VAR</span></a><span class=cF0> symbol to an existing symbol of the same name if it exists in the symbol table 
<a name="l13"></a>(just in just-in-time code).    It also can be used to generate a forward reference.
<a name="l14"></a>
<a name="l15"></a></span><span class=cF2>import</span><span class=cF0> binds a new </span><a href="https://zeal-operating-system.github.io/ZealOS/Kernel/KernelA.HH.html#l828"><span class=cF4>HTT_FUN</span></a><span class=cF0> or </span><a href="https://zeal-operating-system.github.io/ZealOS/Kernel/KernelA.HH.html#l825"><span class=cF4>HTT_GLOBAL_VAR</span></a><span class=cF0> symbol to a symbol of the same name imported from the task's symbol table at </span><span class=cF4>
<a name="l16"></a></span><a href="https://zeal-operating-system.github.io/ZealOS/Kernel/KLoad.ZC.html#l208"><span class=cF4>Load</span></a><span class=cF0>() time.  If no symbol exists to bind to at </span><a href="https://zeal-operating-system.github.io/ZealOS/Kernel/KLoad.ZC.html#l208"><span class=cF4>Load</span></a><span class=cF0>() time, the code using this symbol will be left incomplete until the 
<a name="l17"></a>symbol is defined.
<a name="l18"></a>
<a name="l19"></a>
<a name="l20"></a></span><span class=cF2>_extern</span><span class=cF0> binds a new </span><a href="https://zeal-operating-system.github.io/ZealOS/Kernel/KernelA.HH.html#l828"><span class=cF4>HTT_FUN</span></a><span class=cF0> or </span><a href="https://zeal-operating-system.github.io/ZealOS/Kernel/KernelA.HH.html#l825"><span class=cF4>HTT_GLOBAL_VAR</span></a><span class=cF0> symbol to an existing symbol, of a <blink>different</blink> name.  It must exists in the symbol 
<a name="l21"></a>table.  Basically, this binds C to asm.
<a name="l22"></a>
<a name="l23"></a></span><span class=cF2>_import</span><span class=cF0> binds a new </span><a href="https://zeal-operating-system.github.io/ZealOS/Kernel/KernelA.HH.html#l828"><span class=cF4>HTT_FUN</span></a><span class=cF0> or </span><a href="https://zeal-operating-system.github.io/ZealOS/Kernel/KernelA.HH.html#l825"><span class=cF4>HTT_GLOBAL_VAR</span></a><span class=cF0> symbol to a symbol, of a <blink>different</blink> name imported from the task's symbol table at </span><span class=cF4>
<a name="l24"></a></span><a href="https://zeal-operating-system.github.io/ZealOS/Kernel/KLoad.ZC.html#l208"><span class=cF4>Load</span></a><span class=cF0>() time.    If no symbol exists to bind to at </span><a href="https://zeal-operating-system.github.io/ZealOS/Kernel/KLoad.ZC.html#l208"><span class=cF4>Load</span></a><span class=cF0>() time, the code using this symbol will be left incomplete until the 
<a name="l25"></a>symbol is defined.  Basically, this binds C to asm from elsewhere.
<a name="l26"></a>
<a name="l27"></a>
<a name="l28"></a></span><span class=cF5>Ahead of Time Compilation</span><span class=cF0>
<a name="l29"></a>                        </span><span class=cF2>G</span><span class=cF0>lobalScope / </span><span class=cF2>F</span><span class=cF0>unctionScope
<a name="l30"></a>                        | </span><span class=cF2>C</span><span class=cF0>odeHeap / </span><span class=cF2>D</span><span class=cF0>ataHeap / </span><span class=cF2>S</span><span class=cF0>tack / </span><span class=cF2>R</span><span class=cF0>egister
<a name="l31"></a>                        | | TaskHashEntry: Export</span><span class=cF2>S</span><span class=cF0>ysSym / </span><span class=cF2>D</span><span class=cF0>efine / </span><span class=cF2>F</span><span class=cF0>unction / </span><span class=cF2>C</span><span class=cF0>lass
<a name="l32"></a>                        | | | UsageScope: </span><span class=cF2>M</span><span class=cF0>odule / </span><span class=cF2>A</span><span class=cF0>smLocal / Asm</span><span class=cF2>B</span><span class=cF0>lk / </span><span class=cF2>T</span><span class=cF0>askAndChildren / </span><span class=cF2>F</span><span class=cF0>unction
<a name="l33"></a>                        | | | |UsageScope: </span><span class=cF2>G</span><span class=cF0>lbl / Asm</span><span class=cF2>L</span><span class=cF0>ocal / </span><span class=cF2>R</span><span class=cF0>emainder / </span><span class=cF2>g</span><span class=cF0>lblThisBlkAndRemainder
<a name="l34"></a>                        | | | || </span><span class=cF2>S</span><span class=cF0>taticVarInit / </span><span class=cF2>D</span><span class=cF0>ynamicVarInitAllowed / </span><span class=cF2>N</span><span class=cF0>oInitAllowed
<a name="l35"></a>                        | | | || | Are dups allowed within the namespace? A dup overshadows the original.
<a name="l36"></a>                        | | | || | </span><span class=cF2>D</span><span class=cF0>upsAllowed / </span><span class=cF2>N</span><span class=cF0>oDups / NoDupsBut</span><span class=cF2>P</span><span class=cF0>ad / </span><span class=cF2>W</span><span class=cF0>arningUnlessClosedOut
<a name="l37"></a>
<a name="l38"></a>asm export  </span><span class=cF2>label::</span><span class=cF0>     G C S MG   N
<a name="l39"></a>asm         </span><span class=cF2>label:</span><span class=cF0>      G C   MG   N
<a name="l40"></a>asm local   </span><span class=cF2>@@label:</span><span class=cF0>    G C   AL   N
<a name="l41"></a>asm </span><span class=cF2>IMPORT  label;</span><span class=cF0>      G C   MR   N
<a name="l42"></a>asm export  </span><span class=cF2>label::</span><span class=cF0>     F C S BG   N
<a name="l43"></a>asm         </span><span class=cF2>label:</span><span class=cF0>      F C   BG   N
<a name="l44"></a>asm local   </span><span class=cF2>@@label:</span><span class=cF0>    F C   AL   N
<a name="l45"></a>asm </span><span class=cF2>IMPORT  label;</span><span class=cF0>      F C   BR   N
<a name="l46"></a>C   goto    </span><span class=cF2>label:</span><span class=cF0>      F C   FG   N
<a name="l47"></a>
<a name="l48"></a>            </span><span class=cF2>#define</span><span class=cF0>     x     MR   D
<a name="l49"></a>            function    G C S MR   D
<a name="l50"></a>            variable    F R   FR   N
<a name="l51"></a>            variable    F S   FR   N
<a name="l52"></a></span><span class=cF2>static</span><span class=cF0>      variable    F C   FR D N
<a name="l53"></a>            variable    G C S MR D D
<a name="l54"></a>            variable    G D   MR N D
<a name="l55"></a>            </span><span class=cF2>class</span><span class=cF0>       G     MR   D
<a name="l56"></a>class       member      G     MR   P
<a name="l57"></a></span><span class=cF2>extern      class</span><span class=cF0>       G     MR   D
<a name="l58"></a></span><span class=cF2>extern</span><span class=cF0>      function    G C   MR   W
<a name="l59"></a></span><span class=cF2>import</span><span class=cF0>      function    G C   MR   D
<a name="l60"></a></span><span class=cF2>import</span><span class=cF0>      variable    G C   MR   D
<a name="l61"></a></span><span class=cF2>_extern</span><span class=cF0>     function    G C   MR   D
<a name="l62"></a></span><span class=cF2>_extern</span><span class=cF0>     variable    G C   MR   D
<a name="l63"></a></span><span class=cF2>_import</span><span class=cF0>     function    G C   MR   D
<a name="l64"></a></span><span class=cF2>_import</span><span class=cF0>     variable    G C   MR   D
<a name="l65"></a>
<a name="l66"></a>
<a name="l67"></a></span><span class=cF5>Just in Time Compilation</span><span class=cF0>
<a name="l68"></a>                        </span><span class=cF2>G</span><span class=cF0>lobalScope / </span><span class=cF2>F</span><span class=cF0>unctionScope
<a name="l69"></a>                        | </span><span class=cF2>C</span><span class=cF0>odeHeap / </span><span class=cF2>D</span><span class=cF0>ataHeap / </span><span class=cF2>S</span><span class=cF0>tack / </span><span class=cF2>R</span><span class=cF0>egister
<a name="l70"></a>                        | | TaskHashEntry: Export</span><span class=cF2>S</span><span class=cF0>ysSym / </span><span class=cF2>D</span><span class=cF0>efine / </span><span class=cF2>F</span><span class=cF0>unction / </span><span class=cF2>C</span><span class=cF0>lass
<a name="l71"></a>                        | | | UsageScope: </span><span class=cF2>M</span><span class=cF0>odule / </span><span class=cF2>A</span><span class=cF0>smLocal / Asm</span><span class=cF2>B</span><span class=cF0>lk / </span><span class=cF2>T</span><span class=cF0>askAndChildren / </span><span class=cF2>F</span><span class=cF0>unction
<a name="l72"></a>                        | | | |UsageScope: </span><span class=cF2>G</span><span class=cF0>lbl / Asm</span><span class=cF2>L</span><span class=cF0>ocal / </span><span class=cF2>R</span><span class=cF0>emainder / </span><span class=cF2>g</span><span class=cF0>lblThisBlkAndRemainder
<a name="l73"></a>                        | | | || </span><span class=cF2>S</span><span class=cF0>taticVarInit / </span><span class=cF2>D</span><span class=cF0>ynamicVarInitAllowed / </span><span class=cF2>N</span><span class=cF0>oInitAllowed
<a name="l74"></a>                        | | | || | Are dups allowed within the namespace? A dup overshadows the original.
<a name="l75"></a>                        | | | || | </span><span class=cF2>D</span><span class=cF0>upsAllowed / </span><span class=cF2>N</span><span class=cF0>oDups / NoDupsBut</span><span class=cF2>P</span><span class=cF0>ad / </span><span class=cF2>W</span><span class=cF0>arningUnlessClosedOut
<a name="l76"></a>
<a name="l77"></a>asm export  </span><span class=cF2>label::</span><span class=cF0>     G C S Tg   N
<a name="l78"></a>asm         </span><span class=cF2>label:</span><span class=cF0>      G C   BG   N
<a name="l79"></a>asm local   </span><span class=cF2>@@label:</span><span class=cF0>    G C   AL   N
<a name="l80"></a>asm </span><span class=cF2>IMPORT  label;</span><span class=cF0>      G C   TR   N
<a name="l81"></a>asm export  </span><span class=cF2>label::</span><span class=cF0>     F C   BG   N
<a name="l82"></a>asm         </span><span class=cF2>label:</span><span class=cF0>      F C   BG   N
<a name="l83"></a>asm local   </span><span class=cF2>@@label:</span><span class=cF0>    F C   AL   N
<a name="l84"></a>asm </span><span class=cF2>IMPORT  label;</span><span class=cF0>      F C   BR   N
<a name="l85"></a>C   goto    </span><span class=cF2>label:</span><span class=cF0>      F C   FG   N
<a name="l86"></a>
<a name="l87"></a>            </span><span class=cF2>#define</span><span class=cF0>     x   D TR   D
<a name="l88"></a>            function    G C F TR   D
<a name="l89"></a>            variable    F R   FR   N
<a name="l90"></a>            variable    F S   FR   N
<a name="l91"></a></span><span class=cF2>static</span><span class=cF0>      variable    F C   FR D N
<a name="l92"></a>            variable    G C G TR D D
<a name="l93"></a>            variable            G D G TR S D
<a name="l94"></a>            </span><span class=cF2>class</span><span class=cF0>       G   C TR   D
<a name="l95"></a>class       member      G     TR   P
<a name="l96"></a></span><span class=cF2>extern      class</span><span class=cF0>       G   C TR   D
<a name="l97"></a></span><span class=cF2>extern</span><span class=cF0>      function    G C F TR   W
<a name="l98"></a></span><span class=cF2>extern</span><span class=cF0>      variable    G C G TR   D
<a name="l99"></a></span><span class=cF2>extern</span><span class=cF0>      variable    G D G TR   D
<a name="l100"></a></span><span class=cF2>_extern</span><span class=cF0>     function    G C F TR   D
<a name="l101"></a></span><span class=cF2>_extern</span><span class=cF0>     variable    G C G TR   D
<a name="l102"></a>
<a name="l103"></a>
<a name="l104"></a>* Goto labels must not have the same name as global scope objects.  GoTo's are rare and we don't want to slow the compiler and 
<a name="l105"></a>add code to fix this.  You will get errors if a collision happens, so it's not very dangerous, but the error message is 
<a name="l106"></a>baffling.
<a name="l107"></a>
<a name="l108"></a>* The member names </span><span class=cF2>pad</span><span class=cF0> and </span><span class=cF2>reserved</span><span class=cF0> are special because multiple instances with the same name are allowed in a class.
<a name="l109"></a>
<a name="l110"></a>* Use </span><span class=cF2>reg</span><span class=cF0> or </span><span class=cF2>noreg</span><span class=cF0> in front of local variable names to override automatic register variable allocation. You can, optionally, 
<a name="l111"></a>specify a register after the </span><span class=cF2>reg</span><span class=cF0> keyword.
<a name="l112"></a> 
<a name="l113"></a>* Local non-reg function variables can be accessed in asm blocks with </span><span class=cF2>&amp;i[RBP]</span><span class=cF0> for example.
<a name="l114"></a>
<a name="l115"></a>* Global variables and functions can be accessed in asm with and </span><span class=cF2>&amp;</span><span class=cF0> as in
<a name="l116"></a>                </span><span class=cF2>MOV             RAX, I64 [&amp;global_var]
<a name="l117"></a>                CALL        I32 &amp;Fun
<a name="l118"></a>                CALL        I32 &amp;SYS_SYM</span><span class=cF0>
<a name="l119"></a>
<a name="l120"></a>* In </span><span class=cF2>JIT</span><span class=cF0> asm code, &amp;SYS_SYM and &amp;Fun don't need </span><span class=cF2>IMPORT</span><span class=cF0>.
<a name="l121"></a>
<a name="l122"></a>* All offspring tasks of a task inherit symbols.
<a name="l123"></a>
<a name="l124"></a>* The </span><span class=cF2>sizeof()</span><span class=cF0> and ZealC structure members can be used in asm blocks.
<a name="l125"></a>
<a name="l126"></a>* Using </span><span class=cF2>&amp;i</span><span class=cF0> in </span><a href="https://zeal-operating-system.github.io/ZealOS/Doc/ZealC.DD.html#l1"><span class=cF4>ZealC</span></a><span class=cF0> or </span><span class=cF2>i.u8[2]</span><span class=cF0> on a local variable, </span><span class=cF2>i</span><span class=cF0>, will force it to </span><span class=cF2>noreg</span><span class=cF0>.
<a name="l127"></a>
<a name="l128"></a>* Using </span><span class=cF2>try</span><span class=cF0>/</span><span class=cF2>catch</span><span class=cF0> in a function will force all local variables to </span><span class=cF2>noreg</span><span class=cF0>.
<a name="l129"></a>
<a name="l130"></a>* An unused gap on the stack is left for </span><span class=cF2>reg</span><span class=cF0> variables.
<a name="l131"></a>
<a name="l132"></a>* Note: </span><span class=cF2>static</span><span class=cF0> function variables do not go on the data heap, no matter the setting of the </span><a href="https://zeal-operating-system.github.io/ZealOS/Kernel/KernelA.HH.html#l1685"><span class=cF4>OPTf_GLOBALS_ON_DATA_HEAP</span></a><span class=cF0>.   They 
<a name="l133"></a>may in the future.
<a name="l134"></a>
<a name="l135"></a>* </span><a href="https://zeal-operating-system.github.io/ZealOS/Kernel/KernelA.HH.html#l1682"><span class=cF4>OPTf_EXTERNS_TO_IMPORTS</span></a><span class=cF0> will treat </span><span class=cF2>_extern</span><span class=cF0> as </span><span class=cF2>_import</span><span class=cF0> and </span><span class=cF2>extern</span><span class=cF0> as </span><span class=cF2>import</span><span class=cF0>.  This allows a header to be used either as a </span><span class=cF2>JIT 
<a name="l136"></a>compiled</span><span class=cF0> or </span><span class=cF2>AOT compiled</span><span class=cF0> header.
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