Cross-Platform Low-Level Language CPL 3 - Language Overview Brian Westphal

Design Overview Designed to be like assembly, except with structure Designed to be compatible as an intermediate language between many types of high level languages and Assembly Designed to be cross-platform compatible

Design Overview Supports: –Nested functions –Variable scoping - global, local (per function level) –Very strict typing –One-dimensional arrays –Function pointers All whitespace can be removed

Extended Design Overview Supports –Dynamic memory allocation/deallocation No deallocation is available with SPIM –I/O with stdin and stdout

Grammar Overview Given in EBNF format, compatible with my parser generator (available at Written in Java

Grammar Overview In the grammar file, instead of Rule : ‘a’ B ; B : ‘b’ B | ; There would be Rule ::= ‘a’ B* B ::= ‘b’

Grammar Overview Regular expressions are in single-quotes –There is no need for a separate scanner Rules are not in single-quotes –Rules can be followed by modifiers: *, +, ? –Other EBNF options are available but not used in this grammar (there are no epsilons or binary subtractions)

Grammar Overview Code can only exist in blocks immediately following a rule: //Supports types for casting and declarations. Type ::= '/(' (IntType | FloatType | CharType | AddressType) '/)' { RETree syntaxTree = (RETree) args; RETree type = (RETree) syntaxTree.get (1); return type.collapse (); }

Grammar Overview The first two sections (sections are denoted by ) are for import statements, and additional functions respectively. The third section is for productions. Other than those things, if you cannot read part of the grammar file, ask me - (and give me 12 to 24 hours to If you have suggestions for making CPL 3 better, (i.e. more complete) please send me as well.

Language Overview - by example: variables vars:;.func_main { return:(i); params:; vars:(i32)$x,(i32)$y; MOV $x (i32)100; MOV $y (i32)0; ADD $y $y $x; RET (i)0; }

Language Overview - by example: functions vars:; #This is a comment.func_main { return:(i); params:; vars:(i32)$fact; func_types:((i32):i32); MOV $1 (i32)5; CALL.func_factorial; MOV $fact $return; }

Language Overview - by example: functions.func_factorial { return:(i32); params:(i32)$value; vars:(i32)$t1; if $value == (i32)0 { RET (i32)1; }

Language Overview - by example: functions else { SUB $t1 $value (i32)1; func_types:((i32):i32); MOV $1 $t1; CALL.func_factorial; MOV $t1 $return; MULT $t1 $t1 $value; RET $t1; }

Language Overview - by example: dynamic memory vars:;.func_main { return:(i); params:; vars:(f32*)$floatArray,(i32)$index; ALLOC $floatArray (i32)100 sizeof(f32); MOV $index (i32)0;

Language Overview - by example: dynamic memory wloop $index < (i32)100 { MOV $floatArray[$index] (f32)0.0; ADD $index $index (i32)1; } DEALLOC $floatArray; RET (i)0; }

Language Overview - by example: nested functions vars:;.func_main { return:(i); params:; vars:(i)$x;.localfunc_increment { return:void; params:(i)$y; vars:;

Language Overview - by example: nested functions ADD $x $x $y; } func_types:((i):i); MOV $1 (i)10; CALL.localfunc_increment; RET (i)0; }

Language Overview - by example: function pointers vars:;.func_squareNum { return:(i); params:(i)$x; vars:(i)$y; MULT $y $x $x; RET $y; }

Language Overview - by example: function pointers.func_main { return:(i); params:; vars:(i)$x,(void*)$funcPointer; MOV $x (i)10; MOV $funcPointer.func_squareNum;

Language Overview - by example: function pointers func_types:((i):i); MOV $1 $x; CALL $funcPointer; MOV $x $return; RET (i)0; }

Language Overview - types //Signed int types. typedef int i; typedef char i8; typedef short i16; typedef int i32; typedef long long i64; typedef i si; typedef i8 si8; typedef i16 si16; typedef i32 si32; typedef i64 si64; //Unsigned int types. typedef unsigned int ui; typedef unsigned char ui8; typedef unsigned short ui16; typedef unsigned int ui32; typedef unsigned long long ui64; //Signed float types. typedef float f; typedef float f32; typedef double f64; typedef f sf; typedef f32 sf32; typedef f64 sf64; //Unsigned float types (no unsigned float in PowerPC or Intel). typedef float uf; typedef float uf32; typedef double uf64; //Char types. typedef char c; typedef char c8; typedef short c16;

Language Overview - variable and type examples (i32)$x(i32)10(i32)-10E6 (f32)$pi(f32) (f32)1.0E-6 (c)$letter(c)’a’(c16)0020 (i*)$pointer(c8*)a0000:B800 (c8)$string[1024]

Language Overview - strings Supported with the MOV statement only MOV $string “Hello World!\n\n”

Language Overview - conditions Conditions do not use parentheses –No complex conditions are allowed (i.e. no &&) The following operations are allowed: =, >, !=

Language Overview - built-in functions Math: ADD, SUB, MULT, DIV, REM, NEG Logical: EQ, GT, GE, LT, LE, NE, AND, NOT, NOR, OR, XOR Bitwise: SHL, SHR, BAND, BOR, BXOR Functions: RET, CALL Branching: JMP, JEZ Memory: ALLOC, DEALLOC Other: MOV, HALT

Language Extensions - I/O The following I/O functions are available via the blackbox programs PrintIntReadInt PrintFloatReadFloat PrintDoubleReadDouble PrintStringReadString

Language Extensions - by example: I/O func_types:(void:i32); MOV $1 (i32)100; CALL.PrintInt; MOV $storage “Hello, World!\n\n” func_types:(void:c8*); MOV $1 $storage; CALL.PrintString; func_types:((i32):void); CALL.ReadInt; MOV $storage $return; func_types:(void:c8*,i32); MOV $1 $storage; MOV $1 (i32)1024; CALL.ReadString;

Blackbox Programs Use the blackbox programs (available at to convert your CPL 3 code into an executable or into SPIM assembly. Will only say - error or no errors, no specific error messages Read the documentation; some things that the compiler allows for are not allowed in the language.

Language References Please see the language reference available at for additional information and examples. This presentation and example files for this presentation will also be posted on that site. Also, be sure to see the rest of the links from for information on my Java parser and regular expression packages.

Comments and Questions Please feel free to ask any additional questions and make any comments at this time