forked from Archive/PX4-Autopilot
136 lines
5.1 KiB
Plaintext
136 lines
5.1 KiB
Plaintext
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AS OF 1/18/04
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TYPES
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- Only types INT, BOOLEAN, CHAR, REAL, SCALAR, SUBRANGE, RECORD and SET
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implemented
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- No PACKED types (actually, types are always packed).
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- FILE OF and TEXT types partially supported
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- Not supported in TYPE block
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- TEXT is defined as FILE OF CHAR vs PACKED FILE OF CHAR
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- No function returning FILE OF; No FILE OF
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procedure/function arguments
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- Only PROGRAM arguments can be declared type FILE OF
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- Only one file identifier per FILE OF declaration in type
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block.
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- SET is limit to 16/32 (# bits in int) adjacent elements
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- Expressions are not strongly typed across different SCALAR types
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(see exprEnum in expr.h)
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- In RECORD CASE, there is no verification that the type of the tag
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is consistent with a case selector; the is check if the case selector
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constants are of the same type as the tag type identifier.
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- No range checks on array indices
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- Pointers
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- Can't pass pointers as VAR parameters
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- No pointer functions ??
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- No pointers to pointers
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STATEMENTS
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- The following statements not implemented:
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- No PROCEDURE call with PROCEDUREs or FUNCTIONs as parameters
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- The following statements are only partially implemented
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- WITH statements cannot be nested.
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- Cannot reference "up the chain" in WITH statements. Eg.
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suppose RECORD "a" contains RECORD "b" which contains "c" and
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that RECORD "a" also contains "d" so that we could write
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a.b.c OR a.d
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Then the following should work but is not yet supported:
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WITH a DO
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BEGIN
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WITH b DO
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BEGIN
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c := ..
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d := .. <== SHOULD WORK!!!
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- GOTO only partially implemented -- no stack corrections
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for GOTOs between loops, blocks, etc. Use is DANGEROUS.
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STANDARD PROCEDURES and FUNCTIONS
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- The following statement procedures/functions not implemented:
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- GET, PUT, PACK, UNPACK, NEW
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- TBD
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- No fieldwidth colon operator on WRITE arguments
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Extended Pascal Features
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- Type STRING is partially implemented.
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- PACKED ARRAY[..] OF CHAR is not a a string.
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NON-standard Pascal extensions/differences
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TYPES
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- ARRAY index type is integer constant specifying size of array
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- Hexadecimal constants.
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- INPUT and OUTPUT parameters in PROGRAM statement are
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predeclared and optional.
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OPERATORS
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- Binary shift operators -- << and >> like in C
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- '#', "<>", and "><" are all equivalent
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COMPILER PSEUDO-OPERATIONS
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- INCLUDE
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STATEMENTS
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- CASE statement expects integer expression for the switch
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variable
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- ELSE in CASE statement
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EXPRESSIONS
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- Assumes sizeof(pointer) == sizeof(integer)
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TODO LIST
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o BUGS
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- Implement PUT and GET.
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- In FUNC/PROC calls, if simpleExpression fails to find a parameter (eg.,
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proc (,,), no error is detected.
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- Type FILE OF is totally busted -- fix it
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- Need to get max string size into stack somehow. Runtime routines like
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strcat and strcatc need to know how big the string storage space is.
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- Need logic to release string stack used by actual parameters after
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function/procedure call.
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- Can't declare new parameters / variables with same name as another
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variable at higher stock. Tokenizer does not return tIDENT.
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- There are lots of cases where the string stack is not being managed
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correctly (e.g., usesSection()).
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- Redirection of input and output is not supported (e.g. see setting of
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input and output in CONST section of pageutils.pas).
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o IMPROVEMENTS
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- In PTKN, verify that string stack does not overflow when
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character added.
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- Option to turn on listing
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- Option to interleave assembly language with listing
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- Option to select string stack size (or let it grow dynamically)
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- Option to select symbol table size (or let it grow dynamically)
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- List file should only be produced if option provided.
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- Provide instrumentation to use the line number data in the
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object files. In debugger, display source line. Allow stepping
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from source line to source line.
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- Optimizer needs to be incorporated into compiler.
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- arrayIndex needs to conform with Pascal standard.
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- Need to have 32-bit integers and address
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- Translation to register model
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- Native code translator
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- Linker and support multiple source files
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- Runtime package
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- Full extended pascal string support
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- Other things from extended pascal: 'list of' 'uses' 'unit'
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- Need to optimize out JMP .+1
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- For compatibility, let 'packed array [n..m] of char;' be equivalent to
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string.
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- Need to review all uses of string stack for identifiers and strings
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that get discarded. Probably should get a get infrastructure.
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- Add 16-bit word type
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o ISSUES
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- What happens in TYPE block if type is sTYPE or sFILE_OF? Need
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to re-think all typing. Maybe replace sTYPE and sFILE_OF with
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sINT_TYPE, sINT_ARRAY_TYPE, ..., sFILE_OF_INT,
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sFILE_OF_INT_ARRAY, etc.
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- Is it really necessary or meaningful to allocate dstack for
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file buffers.
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- Revisit procedure call logic in pexec.c & pdbg.c. First stack parameter
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is calculated but never used.
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- Decide what to do about type filename in tests/src/cgimail.pas
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