The F100-L Assembler¶
Invoking The Assembler¶
USAGE:
F100Asm is an assembler for the Ferranti F100-L CPU.
REQUIRED SWITCHES
-f --filename <filename> specify the assembler source file
OPTIONAL SWITCHES
-o --output <filename> specify file name for assembled code
-g --format <bin|ihex|hex|hex16> set the file format for the assembled code
- default is hex
-e --endianness <little|big> set endianness of byte oriented output
- default is little-endian
-n --nolisting suppress the listing to stdout while the
program runs
-s --symboltable output symbol table at end of listing
-l --labelsonly include only labels in the symbol table output (default)
-f --fullsymbols include all symbols in the symbol table output
-h --help print this help message
If no output filename is provided the assembler just produces the normal
listing output to stdout.
EXAMPLES
python3.5 F100Asm.py -f test.asm -o file.bin -g bin -e little
Assembler File Format¶
Comments¶
Comments can be placed anywhere in the code and start with the semi-colon (;) character, e.g.
ADDS 0x134 ; add the magic number to the accumulator
Labels¶
Labels can be placed anywhere in the code and will be evaluated during the first assembly pass.
Labels must start with an alphabetic character or an underscore, end with a ‘:’ and any combination of alphanumeric characters or underscores is allowed in between.
All labels and variables are case insensitive; they will all be converted to upper case during symbol table processing. e.g.
LOOP_TOP: SRL 0x01 A
Directives¶
F100ASM supports the following directives, all of which start with the dot (.) character
.ORG <address>.EQU <variable name> <expression>.DATA <data> [, <data> [, ... ]]].WORD <data> [, <data> [, ... ]]]
.ORG¶
.ORG sets the current instruction address to the value supplied before assembling the next instruction. e.g.
.ORG 0x0800 ; Instruction execution starts at 0x800 following a reset when AdSel is left floating or tied high
.EQU¶
.EQU is used to assign expressions or values to variable names. e.g.
.EQU PTR_START 0x100
.EQU STK_PTR1 PTR_START+1
.EQU MEMTOP 0x7FFF
.EQU STK_SIZE 0x0400
.EQU STK_BOT MEMTOP - STK_SIZE
F100ASM uses the Python ASR parser class to allow parsing of any valid Python expression. All expressions must evaulate to an integer number by the end of the first pass through the assembler. Expressions or symbols may be used anywhere a numerical value is allowed.
Like labels all variable names must start with an alphabetic character or an underscore but subsequent characters may be alphanumeric. All variable names are case insensitive.
Note that the two symbols A and C are reserved words and may not be used as variable names.
Labels are treated like any other variable as far as expression parsing is concerned.
.DATA and .WORD¶
.DATA and .WORD are synonyms of each other. These can be followed by a list of comma separated numeric values or expressions on the same line. e.g.:
.WORD 1,1,2,3,5,8 ; Fibonacci numbers
.WORD STK_PTR1, MEMTOP - STKSIZE ; examples of expressions
Unsupported features
F100ASM doesn’t directly support definition of macros or conditional assembly. These features are easily added by pre-processing the assembly source using the C-preprocessor (cpp).
Example¶
# -------------------------------------------------------------------------------------------
# _____________ ____ __ ___ __ __
# / ____< / __ \/ __ \ / / / | _____________ ____ ___ / /_ / /__ _____
# / /_ / / / / / / / /_____/ / / /| | / ___/ ___/ _ \/ __ `__ \/ __ \/ / _ \/ ___/
# / __/ / / /_/ / /_/ /_____/ /___ / ___ |(__ |__ ) __/ / / / / / /_/ / / __/ /
# /_/ /_/\____/\____/ /_____/ /_/ |_/____/____/\___/_/ /_/ /_/_.___/_/\___/_/
#
#
# F 1 0 0 - L * A S S E M B L E R (c) 2016 Revaldinho & BigEd
# -------------------------------------------------------------------------------------------
#
# LINE: ADDR: CODE SOURCE
# ----:-----------:--------------------------------------------------------------------------
1: .EQU _TMP 0x3E8
2: .EQU ping 0x3EA
3: 001A: 8001 LDA 0x0001
4: 001B: 4800 03EA STO .ping
5: .EQU pong 0x3EC
6: 001D: 8001 LDA 0x0001
7: 001E: 4800 03EC STO .pong
8: .EQU new_pong 0x3EE
9: L1:
10: 0020: 8800 03EA LDA .ping
11: 0022: 9800 03EC ADD .pong
12: 0024: 4800 03EE STO .new_pong
13: 0026: 8800 03EC LDA .pong
14: 0028: 4800 03EA STO .ping
15: 002A: 8800 03EE LDA .new_pong
16: 002C: 4800 03EC STO .pong
17: 002E: 8800 03EA LDA .ping
18: 0030: D000 0262 NEQ ,610
19: 0032: 0181 0020 JBC 0x01 CR L1
# -------------------------------------------------------------------------------------------
# 0 Errors
# 0 Warnings
# -------------------------------------------------------------------------------------------
# SymbolTable
# --------------------------------: -------------------------------- : ----------------------
# Symbol : Definition : Value Hex (Decimal)
# --------------------------------: -------------------------------- : ----------------------
# L1 : 32 : 0020 (32)
# NEW_PONG : 0X3EE : 03EE (1006)
# PING : 0X3EA : 03EA (1002)
# PONG : 0X3EC : 03EC (1004)
# _TMP : 0X3E8 : 03E8 (1000)
# --------------------------------: -------------------------------- : ----------------------
# Run time = 0.004 s
# -------------------------------------------------------------------------------------------