ASM modes and directives — SkoolKit 9.6 documentation (original) (raw)

A skool file may contain directives that are processed during the parsing phase. Exactly how a directive is processed (and whether it is executed) depends on the ‘substitution mode’ and ‘bugfix mode’ in which the skool file is being parsed.

ASM directives

The ASM directives recognised by SkoolKit are described in the following subsections.

@assemble

The @assemble directive controls whether assembly language instructions,DEFB, DEFM, DEFS and DEFW statements, and @defb,@defs and @defw directives are converted into byte values for the purpose of populating the memory snapshot.

H is an integer value that determines what is converted in HTML mode, andA is an integer value that determines what is converted in ASM mode:

If H or A is blank or omitted, its value is left unchanged.

Note that setting H or A to something other than the default value of 2 may affect the output of skool macros that inspect or operate on the contents of the memory snapshot:

Version Changes
9.0 The default value of both H and A is 2 (previously 1 and 0)
7.0 The accepted values are 0, 1 and 2 (previously -1, 0 and 1)
6.3 Added support for specifying what’s converted in HTML mode and ASM mode separately, and for switching off conversion entirely
6.1 Added the ability to assemble instructions whose operands contain arithmetic expressions
5.0 New

@bank

The @bank directive either specifies the RAM bank that is mapped to 49152-65535 (0xC000-0xFFFF) in the memory snapshot:

or populates a specific RAM bank in the memory snapshot from the contents of another skool file:

When the first @bank directive in a skool file is processed, the memory snapshot is converted from 48K to 128K and the 128K ROM is loaded.

Version Changes
9.1 New

@bfix

The @bfix directive replaces, inserts or removes a label, instruction and comment in @bfix mode.

@bfix=[>][|][+][/][LABEL:][INSTRUCTION][; comment]

or, when removing instructions:

For example:

@label=CMASK @bfix=BMASK: AND B ; Apply the mask 29713 AND C ; This should be 'AND B'

This @bfix directive replaces the instruction AND C with AND B, replaces the label CMASK with BMASK, and also replaces the comment.

Comment continuation lines can be replaced, removed or added by using additional @bfix directives. For example, to replace both comment lines of an instruction that has two:

@bfix=AND B ; This directive replaces the first comment line @bfix= ; and this directive replaces the second comment line 29713 AND C ; Both of these comment lines ; will be replaced

To add a second comment line to an instruction that has only one:

@bfix=AND B ; This directive replaces the first comment line @bfix= ; and this directive adds a second comment line 29713 AND C ; This comment line will be replaced

To replace two comment lines with one:

@bfix=/AND B ; The '/' in this directive effectively terminates the comment 29713 AND C ; This comment line will be replaced ; and this one will be removed

A single instruction can be replaced with two or more by using the |(overwrite) marker. For example, to replace LD HL,0 with LD L,0 andLD H,L:

@bfix=|LD L,0 ; Clear L @bfix=|LD H,L ; Clear H 36671 LD HL,0 ; Clear HL

Two or more instructions can also be replaced with a single instruction. For example, to replace XOR A and INC A with LD A,1:

@bfix=|LD A,1 49912 XOR A 49913 INC A

A sequence of instructions can be replaced by chaining @bfix directives. For example, to swap two XOR instructions:

@bfix=|XOR C @bfix=|XOR B 51121 XOR B 51122 XOR C

This is equivalent to:

@bfix=XOR C 51121 XOR B @bfix=XOR B 51122 XOR C

Note that when @bfix directives are chained like this, the second and subsequent directives replace instruction comments in their entirety, instead of line by line. For example:

@bfix=|LD A,D ; Set A=D @bfix=|XOR B ; Flip the bits 51121 LD A,B ; Set A=B 51122 XOR C ; XOR the contents of the accumulator with the contents of the ; C register

replaces both comment lines of the instruction at 51122 with ‘Flip the bits’.

A sequence of instructions can be inserted before the current instruction by using the > marker. For example:

47191 EX DE,HL ; A mid-block comment. @bfix=>LD (HL),C @bfix=>INC HL 47192 LD (HL),B

This will insert LD (HL),C and INC HL between EX DE,HL andLD (HL),B. The mid-block comment that was above LD (HL),B will now be above LD (HL),C.

A sequence of instructions can be inserted after the current instruction (without first specifying a replacement for it) by using the + marker. For example:

@bfix=+LD (HL),C @bfix=INC HL 47191 EX DE,HL ; A mid-block comment. 47192 LD (HL),B

This will insert LD (HL),C and INC HL between EX DE,HL andLD (HL),B. In this case, the mid-block comment above LD (HL),B will remain there.

The current instruction can be replaced and a sequence of instructions inserted after it by chaining @bfix directives. For example:

@bfix=LD (HL),B ; {Save B and C here @bfix=INC HL ; @bfix=LD (HL),C ; } 61125 LD (HL),A ; Save A here 61126 RET

This will replace LD (HL),A with LD (HL),B and insert INC HL andLD (HL),C before the RET instruction.

An instruction can be removed by using the ! notation. For example:

51184 XOR A @bfix=!51185 51185 AND A ; This instruction is redundant 51186 RET

This removes the redundant instruction at 51185.

An entire entry can be removed by specifying an address range that covers every instruction in the entry:

; Unused @bfix=!40000-40001 c40000 NOP 40001 RET

Version Changes
7.1 Added support for the + marker (to insert an instruction after the current one)
7.0 Added support for specifying the replacement comment over multiple lines, replacing the label, and inserting, overwriting and removing instructions
6.4 Added support for replacing the comment

@bfix block directives

The @bfix block directives define a block of lines that will be inserted or removed in @bfix mode.

The syntax for defining a block that will be inserted in @bfix mode (but left out otherwise) is:

@bfix+begin ... ; Lines to be inserted @bfix+end

The syntax for defining a block that will be removed in @bfix mode (but left in otherwise) is:

@bfix-begin ... ; Lines to be removed @bfix-end

Typically, though, it is desirable to define a block that will be removed in@bfix mode right next to the block that will be inserted in its place. That may be done thus:

@bfix-begin ... ; Instructions to be removed @bfix+else ... ; Instructions to be inserted @bfix+end

which is equivalent to:

@bfix-begin ... ; Instructions to be removed @bfix-end @bfix+begin ... ; Instructions to be inserted @bfix+end

For example:

@bfix-begin 32205 JR Z,32232 ; This should be JR NZ,32232 @bfix+else JR NZ,32232 ; @bfix+end

@bytes

The @bytes directive specifies the byte values to which the next instruction should assemble.

@bytes=value1[,value2...]

This directive is useful only for specifying an alternative set of opcodes for an instruction that has two or more valid sets, such as ‘LD HL,(nn)’ (2A or ED6B) and ‘IM 1’ (ED56 or ED76). It ensures that the memory snapshot constructed by skool2asm.py or skool2html.py, and the output produced by skool2bin.py, will contain the correct byte values at the instruction’s address.

For example:

This @bytes directive makes the NEG instruction that follows assemble to ED4C (instead of the standard ED44).

Version Changes
9.3 New

@defb

The @defb directive makes skool2asm.py and skool2html.pyinsert byte values into the memory snapshot at a given address.

@defb=[address:]value1[,value2...]

If address is omitted, it defaults to the address immediately after the last byte of the previous @defb, @defs or @defw directive preceding the same instruction (if one exists), or to the address of the next instruction otherwise.

The sequence of comma-separated values may be followed by a semicolon (;) and arbitrary text, which will be ignored.

For example:

@defb=30000:5,"Hello" ; Welcome message

This will insert the value 5 followed by the ASCII codes of the characters in “Hello” into the memory snapshot at address 30000.

@defb directives are also processed by sna2skool.py when it is run on a control file; thus the @defb directive can be used to override the contents of the snapshot that is read by sna2skool.py.

@defb directives are also processed by skool2bin.py when the--data option is used.

Version Changes
8.1 The address parameter is optional
6.3 New

@defs

The @defs directive makes skool2asm.py and skool2html.pyinsert a sequence of byte values into the memory snapshot at a given address.

@defs=[address:]length[,value]

If address is omitted, it defaults to the address immediately after the last byte of the previous @defb, @defs or @defw directive preceding the same instruction (if one exists), or to the address of the next instruction otherwise.

The directive may be followed by a semicolon (;) and arbitrary text, which will be ignored.

For example:

@defs=30000:5,$FF ; Five 255s

This will insert the value 255 into the memory snapshot at addresses 30000-30004.

@defs directives are also processed by sna2skool.py when it is run on a control file; thus the @defs directive can be used to override the contents of the snapshot that is read by sna2skool.py.

@defs directives are also processed by skool2bin.py when the--data option is used.

Version Changes
8.1 The address parameter is optional
6.3 New

@defw

The @defw directive makes skool2asm.py and skool2html.pyinsert word values into the memory snapshot at a given address.

@defw=[address:]value1[,value2...]

If address is omitted, it defaults to the address immediately after the last byte of the previous @defb, @defs or @defw directive preceding the same instruction (if one exists), or to the address of the next instruction otherwise.

The sequence of comma-separated values may be followed by a semicolon (;) and arbitrary text, which will be ignored.

For example:

@defw=30000:32768,32775 ; Message addresses

This will insert the word values 32768 and 32775 into the memory snapshot at addresses 30000 and 30002.

@defw directives are also processed by sna2skool.py when it is run on a control file; thus the @defw directive can be used to override the contents of the snapshot that is read by sna2skool.py.

@defw directives are also processed by skool2bin.py when the--data option is used.

Version Changes
8.1 The address parameter is optional
6.3 New

@end

The @end directive may be used to indicate where to stop parsing the skool file for the purpose of generating ASM output. Everything after the @enddirective is ignored by skool2asm.py.

See also @start.

Version Changes
2.2.2 New

@equ

The @equ directive defines an EQU directive that will appear in the ASM output.

For example:

@equ=ATTRS=22528 c32768 LD HL,22528

This will produce an EQU directive (ATTRS EQU 22528) in the ASM output, and replace the operand of the instruction at 32768 with a label: LD HL,ATTRS.

Version Changes
5.4 New

@expand

The @expand directive specifies an arbitrary piece of text - intended to consist of one or more SMPL macros - that will be expanded by the ASM writer or HTML writer during initialisation (before any skool macros that appear in skool file annotations or ref file sections are expanded).

For example:

@expand=#DEF(#MAX(a,b) #IF($a>$b)($a,$b))

This @expand directive passes the given #DEF macro to the ASM writer or HTML writer for expansion during initialisation; this has the effect of making the user-defined #MAX macro available for use immediately anywhere in the skool file (and any secondary skool files if the directive appears in the main skool file) or ref files.

If text begins with +, it is appended to the text of the previous@expand directive (with the + removed); this enables long macro definitions to be split over multiple lines. For example:

@expand=#DEF(#OLIST()(items) @expand=+ #LET(n=1) @expand=+ #LIST @expand=+ #FOREACH($items)(item,{ #EVAL({n}). item } #LET(n={n}+1)) @expand=+ LIST# @expand=+)

These @expand directives make the #OLIST macro available, which can then be used to create a numbered list of items:

See also the Expand parameter in the [Config] section, which may be used instead of the @expand directive if there is no need to expandtext in ASM mode.

Version Changes
8.4 Added support for the + notation
8.2 New

@if

The @if directive conditionally processes other ASM directives based on the value of an arithmetic expression.

See Numeric parameters for details on the operators that may be used in the expr parameter.

For example:

@if({mode[case]}==1))(replace=/#hl/hl,replace=/#hl/HL)

would process replace=/#hl/hl if in lower case mode, or replace=/#hl/HLotherwise.

The true and false parameters may be supplied in the same way as they are for the #IF macro. See String parameters for more details.

Version Changes
6.4 New

@ignoreua

The @ignoreua directive suppresses warnings that would otherwise be printed (during the rendering phase) concerning addresses not converted to labels in the comment that follows. The comment may be an entry title, an entry description, a register description section, a block start comment, a mid-block comment, a block end comment, or an instruction-level comment.

@ignoreua[=addr1[,addr2...]]

Although specifying a list of addresses is optional, doing so has the advantage that if another unconvertible address is added to the comment later on, a warning will appear for it, at which point you can decide whether to fix it (in case it was added by mistake) or add it to the list.

To apply the directive to an entry title:

@ignoreua=32768 ; Prepare data at 32768 c32768 LD A,(HL)

If the @ignoreua directive were not present, a warning would be printed about the entry title containing an address (32768) that has not been converted to a label.

To apply the directive to an entry description:

; Prepare data in page 128 ; @ignoreua ; This routine operates on the data at 32768. c49152 LD A,(HL)

If the @ignoreua directive were not present, a warning would be printed about the entry description containing an address (32768) that has not been converted to a label.

To apply the directive to a register description section:

; Prepare data in page 128 ; ; This routine operates on the data in page 128. ; @ignoreua ; HL 32768 c49152 LD A,(HL)

If the @ignoreua directive were not present, a warning would be printed about the register description containing an address (32768) that has not been converted to a label.

To apply the directive to a block start comment:

; Prepare data in page 128 ; ; This routine operates on the data in page 128. ; ; HL 128*256 ; @ignoreua ; First pick up the byte at 32768. c49152 LD A,(HL)

If the @ignoreua directive were not present, a warning would be printed about the start comment containing an address (32768) that has not been converted to a label.

To apply the directive to a mid-block comment:

28913 LD L,A @ignoreua ; #REGhl now holds either 32522 or 32600. 28914 LD B,(HL)

If the @ignoreua directive were not present, a warning would be printed about the comment containing addresses (32522, 32600) that have not been converted to labels.

To apply the directive to a block end comment:

44159 JP 63152 @ignoreua ; This routine continues at 63152.

If the @ignoreua directive were not present, a warning would be printed about the comment containing an address (63152) that has not been converted to a label.

To apply the directive to an instruction-level comment:

@ignoreua 60159 LD C,A ; #REGbc now holds 62818

If the @ignoreua directive were not present, a warning would be printed about the comment containing an address (62818) that has not been converted to a label.

Version Changes
8.1 Added the ability to specify the addresses for which to suppress warnings
4.2 Added support for register description sections
2.4.1 Added support for entry titles, entry descriptions, mid-block comments and block end comments

@isub

The @isub directive replaces, inserts or removes a label, instruction and comment in @isub mode.

The syntax is equivalent to that for the @bfix directive.

Version Changes
7.1 Added support for the + marker (to insert an instruction after the current one)
7.0 Added support for specifying the replacement comment over multiple lines, replacing the label, and inserting, overwriting and removing instructions
6.4 Added support for replacing the comment

@isub block directives

The @isub block directives define a block of lines that will be inserted or removed in @isub mode.

The syntax is equivalent to that for the @bfix block directives.

@keep

The @keep directive prevents the substitution of labels for numeric values in the operand of the next instruction:

In HTML mode, the @keep directive also prevents the operand from being hyperlinked.

For example:

@keep 28328 LD BC,24576 ; #REGb=96, #REGc=0

If the @keep directive were not present, the operand (24576) of theLD BC instruction would be replaced with the label of the routine at 24576 (if there is a routine at that address); however, the operand is meant to be a pure data value, not a variable or routine address.

Version Changes
6.2 Added the ability to specify the values to keep; the @keepdirective is applied to instructions that have been replaced by an @isub, @ssub or @rsub directive

@label

The @label directive sets the label for the next instruction.

For example:

@label=ENDGAME c24576 XOR A

This sets the label for the routine at 24576 to ENDGAME.

If LABEL is blank (@label=), the next instruction will have its entry point marker removed (if it has one), and be prevented from having a label automatically generated.

If LABEL starts with * (e.g. @label=*LOOP), the next instruction will be marked as an entry point (as if the instruction line in the skool file started with *), in addition to having its label set.

If LABEL is just * (@label=*), the next instruction will be marked as an entry point, and have a label automatically generated.

skool2asm.py automatically uses labels defined by the @labeldirective. skool2html.py includes them in its output if the--asm-labels option is used.

@label directive values are also checked by sna2skool.py while reading a control file. They can be used to prevent an entry point marker from being added to an instruction where it otherwise would be (@label=), or force one to be added where it otherwise wouldn’t (@label=*).

Version Changes
7.0 An entry point marker (*) can be added to or removed from the next instruction
6.3 LABEL may be blank (to prevent the next instruction from having a label automatically generated)

@nowarn

The @nowarn directive suppresses any warnings that would otherwise be reported (during the parsing phase) for the next instruction concerning:

@nowarn[=addr1[,addr2...]]

For example:

@nowarn=25404 25560 LD BC,25404 ; Point #REGbc at the routine at #R25404

If this @nowarn directive were not present, a warning would be printed about the operand (25404) being replaced with a routine label (which would be inappropriate if 25404 were intended to be a pure data value).

For another example:

@ofix-begin @nowarn 27872 CALL 27633 ; This should be CALL #R27634 @ofix+else CALL 27634 ; @ofix+end

If this @nowarn directive were not present, a warning would be printed (if not in @ofix mode) about the operand (27633) not being replaced with a label (usually you would want the operand of a CALL instruction to be replaced with a label, but not in this case).

Version Changes
8.1 Added the ability to specify the addresses for which to suppress warnings

@ofix

The @ofix directive replaces, inserts or removes a label, instruction and comment in @ofix mode.

The syntax is equivalent to that for the @bfix directive.

Version Changes
7.1 Added support for the + marker (to insert an instruction after the current one)
7.0 Added support for specifying the replacement comment over multiple lines, replacing the label, and inserting, overwriting and removing instructions
6.4 Added support for replacing the comment

@ofix block directives

The @ofix block directives define a block of lines that will be inserted or removed in @ofix mode.

The syntax is equivalent to that for the @bfix block directives.

@org

The @org directive makes skool2asm.py insert an ORG assembler directive.

Note that the @org directive works only on the first instruction in an entry.

The @org directive also forces skool2bin.py to place the next instruction at the given address.

Version Changes
6.3 The address parameter is optional

@refs

The @refs directive manages the addresses of the referrers of (i.e. the routines that jump to or call) the next instruction.

@refs=[addr1[,addr2...]][:raddr1[,raddr2...]]

This directive can be used to declare one or more additional referrers for an instruction that would not otherwise be identified by theinstruction utility orsnapshot reference calculator (e.g. because the instruction is jumped to indirectly via JP (HL) or RET). As a result:

@refs can also be used to remove one or more referrer addresses that have been added automatically (because the instruction is jumped to or called directly). As a result:

For example:

This @refs directive (in a control file) declares that the routine at 32768 uses the entry point at 40000, and the routine at 49152 does not.

Version Changes
8.2 New

@rem

The @rem directive may be used to make an illuminating comment about a nearby section or other ASM directive in a skool file. The directive is ignored by the parser.

For example:

@rem=The next section of data MUST start at 64000 @org=64000

Version Changes
2.4 The = is required

@remote

The @remote directive creates a remote entry in a skool file. A remote entry enables JR, JP and CALL instructions to be hyperlinked to an entry defined in another skool file.

@remote=code:address[,address2...]

For example:

This directive, if it appeared in a secondary skool file, would enable references to the routine at 29012 and its entry point at 29015 in the main disassembly. It would also enable the #R macro to create a hyperlink to a remote entry point using the form:

Version Changes
6.3 New

@replace

The @replace directive replaces strings that match a regular expression in skool file annotations and ref file section names and contents.

or:

(If the second form is used, any text appearing after the terminating / is ignored.)

For example:

@replace=/#copy/#CHR(169)

This @replace directive replaces all instances of #copy with#CHR(169).

If / appears anywhere in pattern or repl, then an alternative separator should be used; for example:

@replace=|n/a|not applicable

As a convenience for dealing with decimal and hexadecimal numbers, wherever\i appears in pattern, it is replaced by a regular expression group that matches a decimal number or a hexadecimal number preceded by $. For example:

@replace=/#udg\i,\i/#UDG(\1,#PEEK\2)

This @replace directive would replace #udg$a001,40960 with#UDG($a001,#PEEK40960).

Note that string replacements specified by @replace directives are made before skool macros are expanded, and in the order in which the directives appear in the skool file. For example, if we have:

@replace=/#foo\i/#bar\1 @replace=/#bar\i/#EVAL\1,16

then #foo31 would be replaced by #EVAL31,16, but if these directives were reversed:

@replace=/#bar\i/#EVAL\1,16 @replace=/#foo\i/#bar\1

then #foo31 would be replaced by #bar31.

See also the #DEF macro, which is more flexible than @replace for defining new macros.

Version Changes
6.0 Replaces strings in ref file section names
5.1 New

@rfix

The @rfix directive replaces, inserts or removes a label, instruction and comment in @rfix mode.

The syntax is equivalent to that for the @bfix directive.

Version Changes
7.1 Added support for the + marker (to insert an instruction after the current one)
7.0 Added support for specifying the replacement comment over multiple lines, replacing the label, and inserting, overwriting and removing instructions
6.4 Added support for replacing the comment
5.2 New

@rfix block directives

The @rfix block directives define a block of lines that will be inserted or removed in @rfix mode.

The syntax is equivalent to that for the @bfix block directives.

@rom

The @rom directive inserts a copy of the 48K ZX Spectrum ROM into the memory snapshot constructed from the contents of the skool file.

Some reasons why you might want to do this are:

Note that the @rom directive does nothing if the memory snapshot has already been converted to 128K by a @bank directive.

Version Changes
8.7 New

@rsub

The @rsub directive replaces, inserts or removes a label, instruction and comment in @rsub mode.

The syntax is equivalent to that for the @rfix directive.

Version Changes
7.1 Added support for the + marker (to insert an instruction after the current one)
7.0 Added support for specifying the replacement comment over multiple lines, replacing the label, and inserting, overwriting and removing instructions
6.4 Added support for replacing the comment

@rsub block directives

The @rsub block directives define a block of lines that will be inserted or removed in @rsub mode.

The syntax is equivalent to that for the @bfix block directives.

@set

The @set directive sets a property on the ASM writer.

@set directives must be placed somewhere after the @start directive, and before the @end directive (if there is one).

Recognised property names and their default values are:

For example:

This @set directive sets the bullet character to ‘+’.

Version Changes
8.1 Added the table-row-separator property
8.0 Added the table-border-horizontal, table-border-joinand table-border-vertical properties
3.4 Added the handle-unsupported-macros andwrap-column-width-min properties
3.3.1 Added the comment-width-min, indent,instruction-width, label-colons, line-width andwarnings properties
3.2 New

@ssub

The @ssub directive replaces, inserts or removes a label, instruction and comment in @ssub mode.

The syntax is equivalent to that for the @bfix directive.

Version Changes
7.1 Added support for the + marker (to insert an instruction after the current one)
7.0 Added support for specifying the replacement comment over multiple lines, replacing the label, and inserting, overwriting and removing instructions
6.4 Added support for replacing the comment

@ssub block directives

The @ssub block directives define a block of lines that will be inserted or removed in @ssub mode.

The syntax is equivalent to that for the @bfix block directives.

Version Changes
4.4 New

@start

The @start directive indicates where to start parsing the skool file for the purpose of generating ASM output. Everything before the @startdirective is ignored by skool2asm.py.

See also @end.

@writer

The @writer directive specifies the name of the Python class to use to generate ASM output. It must be placed somewhere after the @startdirective, and before the @end directive (if there is one).

@writer=package.module.classname

or:

@writer=/path/to/moduledir:module.classname

The second of these forms may be used to specify a class in a module that is outside the module search path (e.g. a standalone module that is not part of an installed package).

The default ASM writer class is skoolkit.skoolasm.AsmWriter. For information on how to create your own Python class for generating ASM output, see the documentation on extending SkoolKit.

Version Changes
3.3.1 Added support for specifying a module outside the module search path
3.1 New