128 lines
3.5 KiB
Plaintext
128 lines
3.5 KiB
Plaintext
This chapter documents the Backend for the TR3200 cpu.
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@section Legal
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This module is written in 2014 by Luis Panadero Guarde@~no and
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is covered by the vasm copyright without modifications.
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@section General
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This backend accepts TR3200 instructions as described in the
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@uref{https://github.com/trillek-team/trillek-computer, TR3200 specification}
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The target address type is 32 bits.
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Default alignment for sections is 4 bytes. Instructions alignment is 4 bytes.
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Data is aligned to its natural alignment by default, i.e. 2 byte wide data
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alignment is 2 bytes and 4 byte wide data alignment is 4 byte.
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The backend uses TR3200 syntax! This means the left operands are always the
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destination and the right operand is the source (except for single operand
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instructions). Register names have to be prefixed by a '@code{%}'
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(@code{%bp}, @code{%r0}, etc.)
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This means that it should accept WaveAsm assembly files if oldstyle syntax module
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is being used. The instructions are lowercase, @option{-dotdir} option is being used
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and directives are not in the first column.
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@section Extensions
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Predefined register symbols in this backend:
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@itemize @minus
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@item register by number: @code{r0 r1 r2 r3 r4 r5 r6 r7 r8 r9 r10 r11 r12 r13 r14 r15}
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@item special registers by name: @code{bp sp y ia flags}
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@end itemize
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@section Known Problems
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Some known problems of this module at the moment:
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@itemize @minus
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@item This module need to be fully checked, but has been tested building a full
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program that could be found here : @uref{https://github.com/Zardoz89/trillek-firmware}
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@item Instruction relocations are missing.
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@end itemize
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@section Error Messages
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This module has the following error messages:
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@itemize @minus
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@item 2001: illegal operand
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@item 2002: illegal qualifier <%s>
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@item 2003: data size not supported
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@end itemize
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@section Example
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It follows a little example to illustrate TR3200 assembly using
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the oldstyle syntax module (option @option{-dotdir} required):
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@example
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const .equ 0xBEBACAFE ; A constant
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an_addr .equ 0x100 ; Other constant
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; ROM code
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.org 0x100000
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.text
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_start ; Label with or without a ending ":"
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mov %sp, 0x1000 ; Set the initial stack
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mov %r0, 0
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mov %r1, 0xA5
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mov %r2, 0
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storeb %r0, an_addr, %r1
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add %r0, %r2, %bp
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add %r0, %r2, 0
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add %r0, %r0, 10
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add %r0, %r0, 10h
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add %r0, %r0, 0x100010
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add %r0, %r0, (256 + 100) ; vasm parses math expressions
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mov %r2, 0
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mov %r3, 0x10200
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loadb %r6, 0x100200
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loadb %r1, %r2, 0x100200
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loadb %r1, %r2, %r3
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loadb %r4, var1
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push %r0
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.repeat 2 ; directives to repeat stuff!
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push const
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.endrepeat
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.repeat 2
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pop %r5
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.endrepeat
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pop %r0
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rcall foo ; Relative call/jump!
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sleep
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foo: ; Subrutine
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ifneq %r5, 0
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mul %r5, %r5, 2
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sub %r5, %r5, 1
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ret
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; ROM data
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.org 0x100500
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var1 .db 0x20 ; A byte size variable
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.even ; Enforce to align to even address
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var3 .dw 0x1020 ; A word size variable
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var4 .dd 0x0A0B0C20 ; A double word size variable
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str1 .asciiz "Hello world!" ; ASCII string with null termination
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str2 .string "Hello world!" ; ASCII string with null termination
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.fill 5, 0xFF ; Fill 5 bytes with 0xFF
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.reserve 5 ; Reserves space for 5 byte
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@end example
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