STOS.BAS: Difference between revisions
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== STOS .BAS file structure == |
== STOS .BAS file structure == |
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10 bytes Magic "Lionpoulos": STOS basic source |
10 bytes Magic "Lionpoulos": STOS basic source |
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1 long length of source excluding the header |
1 long length of source excluding the header |
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− | 1 long offset to first memory bank |
+ | 1 long offset to first memory bank from end of header |
15 x |
15 x |
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{ |
{ |
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</pre> |
</pre> |
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--[[User:Nyh|Nyh]] 16:18, 10 July 2007 (EDT) |
--[[User:Nyh|Nyh]] 16:18, 10 July 2007 (EDT) |
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== STOS source code format == |
== STOS source code format == |
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The source code is a stream of tokenized basic lines. Each line of STOS code equates to: |
The source code is a stream of tokenized basic lines. Each line of STOS code equates to: |
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+ | {| border="1" class="wikitable" style="text-align:left" |
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+ | |}<br><br> |
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+ | The last line in the source code is always 4 0x00 bytes. |
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There are some special tokens, that may take up more than one byte: |
There are some special tokens, that may take up more than one byte: |
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− | Value Meaning Notes |
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− | 0x00 Enf of line marker 1 byte: token (0x00) |
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+ | ! style="background:#FFE3BC;" | Value |
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+ | ! style="background:#FFDEE7;" | Command |
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+ | ! style="background:#B4C9CE;" | Notes |
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+ | | 0x8A<br><br><br> || Rem or '<br><br><br> || 1 byte: token (0x8A)<br>1 byte: unknown purpose<br>''x'' bytes: ASCII text, terminated by 0x00 end of line token |
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⚫ | | 0xA8<br>0xC0<br><br><br><br><br> || Extension instruction<br>Extension function<br><br><br><br> || 1 byte: token (0xA8 or 0xC0)<br>1 byte: extension index - extension A = 0x00, B = 0x01, … Z = 0x19<br>1 byte: lookup token - look this value up in the [[STOS LOOKUP TABLES|extensions lookup table]]<br>Note: The extension index is relevant to the extension configuration at the time of saving the .BAS file. So for a .BAS file that contains extension commands to be correctly interpreted when loading, the same extensions need to be present at the same letters.<br><br> |
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+ | | 0x98<br>0x99<br>0x9A<br>0x9B<br>0x9C<br>0x9D<br>0x9E<br>0x9F || Goto<br>Gosub<br>Then<br>Else<br>Restore<br>For<br>While<br>Repeat || 1 byte: token (0x98, 0x99, … 0x9F)<br>0 or 1 byte: padding to make the next byte appear at an even position<br>4 bytes: unknown purpose<br><br><br><br><br><br> |
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⚫ | | 0xA0<br>0xB8<br><br> || Extended instruction<br>Extended function || 1 byte: token (0xA0 or 0xB8)<br>1 byte: another token, to lookup in either the extended instructions table or extended functions [[STOS LOOKUP TABLES|lookup table]]<br>Note: These are nothing to do with extensions, and I guess were added when the programmers realised the wouldn’t fit all the instructions into values 0x80 - 0xFF? |
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+ | | 0xFA<br><br><br><br><br> || Variable name<br><br><br><br><br> || 1 byte: token (0xFA)<br>0 or 1 byte: padding to make the next byte appear at an even position<br>1 byte: 1st bit set if var is a string, 2nd bit if var is a float, 3rd bit set if var is an array, remaining 5 bits, length of variable name<br>3 bytes: unknown purpose<br>''x'' bytes: ASCII variable name, including any '$' or '#' postfix. |
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+ | | 0xFB<br> || Integer (binary) || ? |
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+ | | 0xFC<br><br><br><br><br> || String literal<br><br><br><br><br> || 1 byte: token (0xFC)<br>0 or 1 byte: padding to make the next byte appear at an even position<br>2 bytes: unknown purpose<br>1 word: string length<br>''x'' bytes: ASCII string value |
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+ | | 0xFD<br> || Integer (hexadecimal) || ? |
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+ | | 0xFF<br><br><br><br><br> || Floating point number<br><br><br><br> || 1 byte: token (0xFE)<br>0 or 1 byte: padding to make the next byte appear at an even position<br>1 word: number value - 1st 24 bits are the mantissa, 25th bit is the sign, last 7 bits are the exponent<br>4 bytes: unknown purpose<br>Note: to convert to a readable format, each bit of the mantissa = 2 ^ (bit_position + exponent - 88.0). Add up the values indicated by each bit in the mantissa. Accurate to 5 decimal places. |
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+ | |} |
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− | 0x8A Rem or ' 1 byte: token (0x8A) |
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− | 1 byte: unknown purpose |
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− | x bytes: ASCII text, terminated by 0x00 end of line token |
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− | 0xA8 Extension instruction 1 byte: token (0xA8 or 0xC0) |
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− | 0xC0 Extension function 1 byte: extension index - extension A = 0x00, B = 0x01, … Z = 0x19 |
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− | 1 byte: lookup token - look this value up in the extensions lookup table |
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− | 0x98 Goto 1 byte: token (0x98, 0x99, … 0x9F) |
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− | 0x9A Then 4 bytes: unknown purpose |
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− | 0x9B Else |
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− | 0x9C Restore |
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− | 0x9D For |
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− | 0x9E While |
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− | 0x9F Repeat |
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+ | [[Category:STOS BASIC]] |
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− | 0xA0 Extended instruction 1 byte: token (0xA0 or 0xB8) |
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+ | [[Category:Data Formats]] |
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− | 0xB8 Extended function 1 byte: another token, to lookup in either the extended instructions table or extended functions table |
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− | 0xFA Variable name 1 byte: token (0xFA) |
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− | 0 or 1 byte: padding to make the next byte appear at an even position |
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− | 1 byte: first 3 bits unknown purpose, remaining 5 bits, length of variable name |
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− | 3 bytes: unknown purpose |
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− | x bytes: ASCII variable name |
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− | 0xFC String literal 1 byte: token (0xFC) |
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− | 0 or 1 byte: padding to make the next byte appear at an even position |
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− | 2 bytes: unknown purpose |
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− | 1 word: string length |
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− | x bytes: ASCII string value |
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− | 0xFE Integer 1 byte: token (0xFE) |
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− | 0 or 1 byte: padding to make the next byte appear at an even position |
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− | 1 word: integer value |
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− | 0xFF Floating point number 1 byte: token (0xFE) |
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− | 0 or 1 byte: padding to make the next byte appear at an even position |
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− | 1 word: number value - 1st 24 bits are the mantissa, 25th bit is the sign, last 7 bits are the exponent |
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− | 4 bytes: unknown purpose |
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− | Note: to convert to a readable format, each bit of the mantissa = 2 ^ (bit_position + exponent - 88.0). Add up the values indicated by each bit in the mantissa. |
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Latest revision as of 06:48, 20 January 2017
STOS .BAS file structure
BAS_HEADER { 10 bytes Magic "Lionpoulos": STOS basic source 1 long length of source excluding the header 1 long offset to first memory bank from end of header 15 x { 1 byte bank type 3 byte bank length } ___+ 78 byte header size } ?? byte source code
--Nyh 16:18, 10 July 2007 (EDT)
STOS source code format
Bear in mind a Motorola 68000 based system uses big endian format, and 1 word is 4 bytes (32 bits), 1/2 word is 2 bytes (16 bits). To interpret on an Intel / PC based system, you will need to reverse the order of the bytes in each word / 1/2 word.
Credit should go to the writer of Amos file formats page, as I found it very useful, especially for the floating point translation. Also I got the lookup table information from the STOS source code - thanks to lp (Lonny) from the forum for that suggestion.
The source code is a stream of tokenized basic lines. Each line of STOS code equates to:
1/2 word | The length of the line in bytes, including this value and the line number |
1/2 word | The line number |
x bytes | Tokenized code (length: line length - 4) |
The last line in the source code is always 4 0x00 bytes.
Most tokens are one byte, and represents one command or function. To find the name of the command or function, look up the byte value in the lookup table.
Token bytes start from 0x80 onwards. If the token value <= 0x7F, use its ascii value.
There are some special tokens, that may take up more than one byte:
Value | Command | Notes |
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0x00 |
End of line marker |
1 byte: token (0x00) 0 or 1 byte: padding to make the next byte appear at an even position |
0x8A |
Rem or ' |
1 byte: token (0x8A) 1 byte: unknown purpose x bytes: ASCII text, terminated by 0x00 end of line token |
0xA8 0xC0 |
Extension instruction Extension function |
1 byte: token (0xA8 or 0xC0) 1 byte: extension index - extension A = 0x00, B = 0x01, … Z = 0x19 1 byte: lookup token - look this value up in the extensions lookup table Note: The extension index is relevant to the extension configuration at the time of saving the .BAS file. So for a .BAS file that contains extension commands to be correctly interpreted when loading, the same extensions need to be present at the same letters. |
0x98 0x99 0x9A 0x9B 0x9C 0x9D 0x9E 0x9F |
Goto Gosub Then Else Restore For While Repeat |
1 byte: token (0x98, 0x99, … 0x9F) 0 or 1 byte: padding to make the next byte appear at an even position 4 bytes: unknown purpose |
0xA0 0xB8 |
Extended instruction Extended function |
1 byte: token (0xA0 or 0xB8) 1 byte: another token, to lookup in either the extended instructions table or extended functions lookup table Note: These are nothing to do with extensions, and I guess were added when the programmers realised the wouldn’t fit all the instructions into values 0x80 - 0xFF? |
0xFA |
Variable name |
1 byte: token (0xFA) 0 or 1 byte: padding to make the next byte appear at an even position 1 byte: 1st bit set if var is a string, 2nd bit if var is a float, 3rd bit set if var is an array, remaining 5 bits, length of variable name 3 bytes: unknown purpose x bytes: ASCII variable name, including any '$' or '#' postfix. |
0xFB |
Integer (binary) | ? |
0xFC |
String literal |
1 byte: token (0xFC) 0 or 1 byte: padding to make the next byte appear at an even position 2 bytes: unknown purpose 1 word: string length x bytes: ASCII string value |
0xFD |
Integer (hexadecimal) | ? |
0xFE |
Integer |
1 byte: token (0xFE) 0 or 1 byte: padding to make the next byte appear at an even position 1 word: integer value |
0xFF |
Floating point number |
1 byte: token (0xFE) 0 or 1 byte: padding to make the next byte appear at an even position 1 word: number value - 1st 24 bits are the mantissa, 25th bit is the sign, last 7 bits are the exponent 4 bytes: unknown purpose Note: to convert to a readable format, each bit of the mantissa = 2 ^ (bit_position + exponent - 88.0). Add up the values indicated by each bit in the mantissa. Accurate to 5 decimal places. |
--Darklight 20:54, 2 September 2007 (EDT)