mirror of
https://github.com/RevCurtisP/C02.git
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Merge pull request #1 from RevCurtisP/select
Implemented SELECT, CASE, and DEFAULT statements
This commit is contained in:
RevCurtisP
GitHub
commit
eec6b17878
5
c02.c
5
c02.c
@ -54,10 +54,7 @@ void pword()
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getwrd();
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ACMNT(word);
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DEBUG("Parsing Word '%s'\n", word);
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if (xstmnt[0])
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if (wordis(xstmnt))
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xstmnt[0] = 0;
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else
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if (xstmnt[0] && !wordis(xstmnt))
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ERROR("Expected '%s' statement\n", xstmnt, EXIT_FAILURE);
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if (!pmodfr() && !ptype(MTNONE))
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pstmnt(); //Parse Statement
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138
c02.ppx
138
c02.ppx
@ -2,32 +2,7 @@
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<settings version="1.0">
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<category name="expr.h" />
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<category name="cond.h" />
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<category name="asm.h" />
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<category name="c02.c" />
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<category name="stmnt.c">
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<category name="Window">
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<property name="Left" type="integer">-8</property>
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<property name="Top" type="integer">-31</property>
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<property name="Right" type="integer">952</property>
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<property name="Bottom" type="integer">422</property>
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<property name="Maximized" type="integer">1</property>
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<property name="Active" type="integer">1</property>
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</category>
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</category>
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<category name="asm.c" />
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<category name="vars.c" />
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<category name="parse.c">
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<category name="Window">
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<property name="Left" type="integer">52</property>
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<property name="Top" type="integer">52</property>
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<property name="Right" type="integer">760</property>
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<property name="Bottom" type="integer">362</property>
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<property name="Maximized" type="integer">0</property>
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<property name="Active" type="integer">0</property>
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</category>
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</category>
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<category name="include.c" />
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<category name="expr.c">
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<category name="asm.h">
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<category name="Window">
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<property name="Left" type="integer">78</property>
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<property name="Top" type="integer">78</property>
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@ -37,7 +12,116 @@
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<property name="Active" type="integer">0</property>
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</category>
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</category>
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<category name="c02.c">
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<category name="Window">
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<property name="Left" type="integer">0</property>
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<property name="Top" type="integer">0</property>
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<property name="Right" type="integer">952</property>
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<property name="Bottom" type="integer">310</property>
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<property name="Maximized" type="integer">0</property>
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<property name="Active" type="integer">0</property>
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</category>
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</category>
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<category name="stmnt.c">
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<category name="Window">
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<property name="Left" type="integer">26</property>
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<property name="Top" type="integer">26</property>
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<property name="Right" type="integer">978</property>
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<property name="Bottom" type="integer">336</property>
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<property name="Maximized" type="integer">0</property>
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<property name="Active" type="integer">0</property>
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</category>
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</category>
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<category name="asm.c">
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<category name="Window">
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<property name="Left" type="integer">52</property>
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<property name="Top" type="integer">52</property>
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<property name="Right" type="integer">760</property>
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<property name="Bottom" type="integer">362</property>
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<property name="Maximized" type="integer">0</property>
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<property name="Active" type="integer">0</property>
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</category>
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</category>
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<category name="vars.c">
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<category name="Window">
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<property name="Left" type="integer">52</property>
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<property name="Top" type="integer">52</property>
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<property name="Right" type="integer">1004</property>
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<property name="Bottom" type="integer">362</property>
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<property name="Maximized" type="integer">0</property>
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<property name="Active" type="integer">0</property>
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</category>
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</category>
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<category name="parse.c">
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<category name="Window">
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<property name="Left" type="integer">78</property>
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<property name="Top" type="integer">78</property>
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<property name="Right" type="integer">1030</property>
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<property name="Bottom" type="integer">388</property>
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<property name="Maximized" type="integer">0</property>
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<property name="Active" type="integer">0</property>
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</category>
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</category>
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<category name="include.c">
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<category name="Window">
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<property name="Left" type="integer">104</property>
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<property name="Top" type="integer">104</property>
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<property name="Right" type="integer">1056</property>
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<property name="Bottom" type="integer">414</property>
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<property name="Maximized" type="integer">0</property>
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<property name="Active" type="integer">0</property>
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</category>
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</category>
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<category name="expr.c">
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<category name="Window">
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<property name="Left" type="integer">130</property>
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<property name="Top" type="integer">130</property>
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<property name="Right" type="integer">1082</property>
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<property name="Bottom" type="integer">440</property>
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<property name="Maximized" type="integer">0</property>
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<property name="Active" type="integer">0</property>
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</category>
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</category>
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<category name="parse.h" />
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<category name="common.h" />
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<category name="common.h">
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<category name="Window">
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<property name="Left" type="integer">-8</property>
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<property name="Top" type="integer">-31</property>
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<property name="Right" type="integer">952</property>
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<property name="Bottom" type="integer">422</property>
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<property name="Maximized" type="integer">1</property>
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<property name="Active" type="integer">1</property>
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</category>
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</category>
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<category name="files.c" />
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<category name="common.c">
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<category name="Window">
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<property name="Left" type="integer">26</property>
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<property name="Top" type="integer">26</property>
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<property name="Right" type="integer">978</property>
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<property name="Bottom" type="integer">336</property>
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<property name="Maximized" type="integer">0</property>
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<property name="Active" type="integer">0</property>
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</category>
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</category>
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<category name="label.c">
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<category name="Window">
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<property name="Left" type="integer">104</property>
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<property name="Top" type="integer">104</property>
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<property name="Right" type="integer">812</property>
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<property name="Bottom" type="integer">414</property>
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<property name="Maximized" type="integer">0</property>
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<property name="Active" type="integer">0</property>
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</category>
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</category>
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<category name="cond.c">
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<category name="Window">
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<property name="Left" type="integer">130</property>
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<property name="Top" type="integer">130</property>
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<property name="Right" type="integer">838</property>
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<property name="Bottom" type="integer">440</property>
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<property name="Maximized" type="integer">0</property>
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<property name="Active" type="integer">0</property>
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</category>
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</category>
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</settings>
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43
doc/c02.txt
43
doc/c02.txt
@ -513,9 +513,48 @@ Note: In order to optimize the compiled code, the if and else statements
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are to 6502 relative branch instructions. This limits the amount of
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generated code between the if statement and the end of the if/else block
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to slightly less than 127 characters. This should be sufficient in most
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cases, but larger code blocks can be accomodated using function calls or
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cases, but larger code blocks can be accommodated using function calls or
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goto statements.
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SELECT, CASE, AND DEFAULT STATEMENTS
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The select, case, an default statements are used to execute a specific
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block of code depending on the result of an expression.
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When using the select keyword, it is followed by an expression (surrounded
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by parenthesis) and an opening curly brace, which begins the select block.
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This must then be followed by a case statement.
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Each use of the case keyword is followed by term and a colon. If the
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term is equal to select expression then the code immediately following
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the is executed, otherwise, program execution transfers to the next
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case or default statement.
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The code between two case statements or a case and default statement is
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called a case block. At the end of a case block, program execution
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transfers to the end of the select block (the closing curly brace at
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the end of the default block).
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The last case block must be followed by a default statement. When using
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the default keyword, it is followed by a colon. The code between the
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default statement and the end of the select block (marked with a closing
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curly-brace) is called the default block and is executed if none of
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the case arguments matched the select expression.
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Example:
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puts("You pressed ");
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select (getc()) {
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case $0D: putln("The Enter key");
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case ' ': putln("The space bar");
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case ltr: putln("The character in variable 'ltr'");
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case s[2]: putln("The third character of string 's'");
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default: putln("some other key");
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}
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Note: It's possible for multiple case statement arguments to evaluate to
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the same value. In this case, only the first case block matching the
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select expression will be executed.
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WHILE LOOPS
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The while statement is used to conditionally execute code in a loop. When
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@ -532,7 +571,7 @@ Examples:
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while() if (rdkey()) break; //Wait for a keypress
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Note: While loops are compiled using the 6502 JMP statements, so the code
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blocks may be abritrarily large.
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blocks may be arbitrarily large.
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DO WHILE LOOPS
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@ -7,8 +7,8 @@ C02 only supports one data type: unsigned char.
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POINTERS
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C02 does not support pointer type variables or parameters. However, the
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address-of operator may be used in function calls.
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address-of operator may be used in function calls and the inline
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statement.
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DECLARATIONS
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@ -28,3 +28,10 @@ EXPRESSIONS
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C02 supports the addition, subtraction, bitwise-and, bitwise-or, and
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exclusive-or operators. The multiplication, division, and binary shift
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operators are not supported. These can be implemented through functions.
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STATEMENTS
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Instead of the switch statement, C02 uses the select statement. The
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select statement works almost identically to the switch statement except
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that case blocks do not fall through and the break statement does not
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exit a case block.
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19
label.c
19
label.c
@ -85,8 +85,6 @@ void reqlbl(char* lbname)
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}
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/* Pop Label from Stack and Emit on Next Line */
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int poplbl()
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{
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@ -102,12 +100,27 @@ int poplbl()
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else if (lbtype == LTDWHL)
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strcpy(endlbl, lblnam[lblcnt]);
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//strcpy(cndlbl, lblnam[lblcnt]);
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else if (lbtype == LTCASE)
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strcpy(cndlbl, lblnam[lblcnt]);
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else
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setlbl(lblnam[lblcnt]);
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inblck = lblblk[lblcnt-1];
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if (lbtype != LTCASE)
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inblck = lblblk[lblcnt-1];
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return lbtype;
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}
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/* Get Top Label and Return Type */
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int toplbl(char *rtlbl)
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{
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if (lblcnt) {
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strcpy(rtlbl, lblnam[lblcnt-1]);
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DEBUG("Found top label %s\n", rtlbl);
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return lbltyp[lblcnt-1];
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}
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rtlbl[0] = 0; //Clear Label
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return LTNONE;
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}
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/* Push Label onto Stack *
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* Args: lbltyp - Label type *
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* Uses: curlbl - Label to push */
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2
label.h
2
label.h
@ -18,7 +18,7 @@ int lblcnt; //Number of Labels in stack
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int lblnxt; //Sequence of next label to be generated
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char lbltmp[LABLEN+1]; //Label Temporary Storage
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enum ltypes {LTNONE, LTIF, LTLOOP, LTEND, LTDO, LTDWHL, LTFUNC}; //Label Types
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enum ltypes {LTNONE, LTIF, LTLOOP, LTEND, LTDO, LTDWHL, LTSLCT, LTCASE, LTFUNC}; //Label Types
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void prslbl(); //Parse Label From Code
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void newlbl(char* lbname); //Generate New Block Label
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56
stmnt.c
56
stmnt.c
@ -204,7 +204,7 @@ void pfor() {
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/* parse and compile if statement */
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void pif() {
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DEBUG("Parsing IF statement '%c'\n", nxtchr);
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DEBUG("Parsing IF statement\n", 0);
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expect('(');
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newlbl(cndlbl); //Create New Label
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pshlbl(LTIF,cndlbl); //Push Onto Stack
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@ -214,7 +214,7 @@ void pif() {
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/* parse and compile else statement */
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void pelse() {
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DEBUG("Parsing ELSE statement '%c'\n", nxtchr);
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DEBUG("Parsing ELSE statement\n", 0);
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strcpy(lbltmp, lblasm); //Save Line Label
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lblasm[0] = 0; //and Clear It
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newlbl(skplbl); //Create Skip Label
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@ -306,6 +306,47 @@ void pretrn() {
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lsrtrn = TRUE; //Set RETURN flag
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}
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/* parse and compile select statement */
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void pslct() {
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DEBUG("Parsing SELECT statement\n", 0);
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expect('(');
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prsxpr(')'); //Parse Expression
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newlbl(endlbl); //Create New Label
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pshlbl(LTSLCT,endlbl); //Push Onto Stack
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bgnblk(TRUE); //Check For and Begin Block
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strcpy(xstmnt, "CASE"); //Require Next Statement to be CASE
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}
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/* process end of case block */
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void ecase() {
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if (poplbl(cndlbl) != LTCASE)
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ERROR("%s not at end of CASE block\n", word, EXIT_FAILURE);
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if (toplbl(endlbl) != LTSLCT)
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ERROR("Illegal nesting in SELECT statement\n", 0, EXIT_FAILURE);
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asmlin("JMP", endlbl); //Emit jump over default case
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setlbl(cndlbl); //Set entry point label to emit
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}
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/* parse and compile select statement */
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void pcase() {
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if (strcmp(xstmnt, "CASE") == 0)
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xstmnt[0] = 0; //Clear xstmnt
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else
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ecase("CASE"); //Process end of case block
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prstrm(); //Parse CASE argument
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asmlin("CMP", term); //Emit Comparison
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expect(':');
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newlbl(cndlbl); //Create Conditional Label
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pshlbl(LTCASE, cndlbl); //and Push onto Stack
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asmlin("BNE", cndlbl); //Emit skip of CASE body
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}
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/* parse and compile default statement */
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void pdflt() {
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expect(':');
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ecase(); //Process end of case block
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}
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/* parse and compile while statement */
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void pwhile() {
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DEBUG("Parsing WHILE statement '%c'\n", nxtchr);
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@ -385,15 +426,18 @@ void pstmnt()
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return;
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}
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if (wordis("SWITCH")) {
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punimp();
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return;
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ERROR("SWITCH not implemented. Use SELECT.\n", word, EXIT_FAILURE);
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}
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if (wordis("SELECT")) {
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pslct();
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return;
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}
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if (wordis("CASE")) {
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punimp();
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pcase();
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return;
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}
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if (wordis("DEFAULT")) {
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punimp();
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pdflt();
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return;
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}
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if (wordis("WHILE")) {
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