What's New in v9.3 Astrobe for Arm

Arm Oberon Development System for Windows
Version 9.3.0 Copyright © 2006-2024 CFB Software
Email: support@astrobe.com
Website: www.astrobe.com
A summary of new features and problems fixed since v9.0
Last Updated 17 Oct 2024

Introduction

The following notes apply to all versions of Astrobe for Cortex-M0, M3, M4, M7 and Astrobe for RP2040 (Cortex-M0+) and RP2350 (Cortex-M33) unless specifically noted.

Astrobe is supported on Microsoft Windows 10 and Windows 11 with the Microsoft .NET Framework 4.x or later.  The Installation and Uninstall executables are digitally signed to validate authenticity and integrity.


Code Generation

The following details are of particular interest if you are using the Module and Application Disassemblers:

Instruction Sets

There are two instruction sets, called Thumb-1 and Thumb-2, used in Cortex-M processors  Thumb-1 instructions are 16-bit and most can only access the low general purpose registers r0 .. r7 The equivalent 32-bit Thumb-2 instructions can be used to access additional general purpose registers r8 .. r11. In general Thumb-1 results in smaller code size and Thumb-2 results in better performance.

Most Thumb-1, but only a few Thumb-2, instructions can be used in Cortex-M0. All Thumb-1 and most Thumb-2 instructions can be used in Cortex-M3, M4, M7 and RP2350.

Additional instructions are used in Cortex-M4, M7 and RP2350 for the hardware floating point operations: add, multiply, divide and square root. These are implemented in software (the FPU library module) in Cortex-M0, M3 and RP2040.

Register Usage

Cortex-M0 and RP2040:

Cortex-M3, M4, M7 and RP2350:

Frame Pointer

The frame pointer (FP = r12) is no longer required resulting in less overhead on procedure entry code. The register is reserved for future use.

Numeric Case Statements

Cortex-M0 and RP2040:

Cortex-M3, M4, M7 and RP2350:

Miscellaneous Optimisations


Built-in Procedures

CLEAR

The built-in procedure CLEAR initialises every word in a record or an array variable v to zero.

CLEAR(VAR v: <record or array type>)

It is designed to be used to simplify and optimise the code required to initialise complex data structures. Its use can be seen in the Performance example and procedure InitHeader in the HCFiler library module HCDir.

ORD

The expression which is passed as a parameter to ORD can be a BYTE expression as well as a CHAR, BOOLEAN or SET.

BITS

BITS will report an error if its actual parameter is a BYTE expression. However, ORD can be used to convert the expression to an INTEGER e.g.

setvar := BITS(ORD(bytevar))


SYSTEM Procedures

SYSTEM.ALIGN

PROCEDURE ALIGN()

ALIGN can be used to ensure that the instruction that follows it is aligned on a word boundary. It inserts a NOP instruction at the current code location if necessary.

SYSTEM.EMITH

PROCEDURE EMITH(instruction: INTEGER)

EMITH (EMIT Halfword) inserts the constant value instruction, which represents a 16-bit Arm Thumb instruction, at the current code location. A compilation error results if the value is not a valid 16-bit positive integer.

SYSTEM.VAL

SYSTEM.VAL no longer generates compiler warnings and the read-only restriction has been removed e.g. the following (where x is a word-length variable of any type) is a valid statement :

INC(SYSTEM.VAL(INTEGER, x))

SYSTEM Variables

SYSTEM.FP, SYSTEM.SP, SYSTEM.LNK and SYSTEM.PC have been removed. SYSTEM.LDREG and SYSTEM.REG with values 13 (SP), 14 (LNK) and 15 (PC), should be used instead. Register 12 (FP) is no longer used as a frame pointer.


Oberon Language Extensions

ARRAY OF BYTE

An existing Oberon language extension allows a procedure with a formal parameter which is an array of bytes with a fixed size to accept actual parameters of any type whose size is the same number of bytes.

The converse situation is now also catered for i.e. a procedure with a formal parameter of any type can accept an actual parameter which is an array of bytes of the same size.

These extensions are primarily designed to simplify and optimise the code required for tasks such as de-serialising / serialising complex data structures for Input / Output operations. An example of its use, ByteArrays.mod, is included with the General examples supplied with Astrobe. The following compiler warnings are generated:

Warning: type cast to byte array
Warning: type cast from byte array

NOTE: You can use SYSTEM.VAL for type casting if you would prefer not to use an Oberon Language extension. Examples of its use can be seen in VALByteArrays.mod in the General examples supplied with Astrobe.

Dynamic Local Array Variables

Eliminating the frame pointer resulted in the removal of support for dynamic local array variables. These can be replaced by local array variables with a fixed size.


Oberon Language Clarifications and Restrictions

The format of symbol files and the way they are processed have changed. Consequently, the related sections of Chapter 5 of the Oberon Programmers Guide now read:

Exports

Pointer Types

Record Extensions

All identifiers declared in an extended record must be different from the identifiers declared in its base type record(s). An exception to this is that an identifier declared in an extended record may be the same as the identifier of a private field declared in an imported base type record.


Configuration

Thumb Code is a new configuration option which directs the compiler to make more use of 16-bit Thumb-1 instructions instead of equivalent 32-bit Thumb-2 instructions when generating code. The typical result is a reduction in code size of about 30%. It is permanently checked on for Cortex-M0.

Configuration ID is a new configuration option which can be used for any purpose by the programmer. It is an INTEGER value that can be accessed within an application by reading the value of the variable LinkOptions.ConfigID.

The Line Numbers configuration option has been renamed to Stack Trace to avoid confusion with the Tools > Preferences > Line Numbers option.

The obsolete Crystal Frequency configuration option has been removed.


File Menu

If a new folder is specified when using the Save As command, the folder name is used as the default folder the next time Save As is used.


Project Menu

Disassemble Module

Compile, Build and Rebuild

Link

The options shown in the linker map for each module now include t+ or t- corresponding to whether the Thumb Code configuration option was checked on or off when that module was last compiled.

Run

Astrobe Terminal displays error messages instead of exceptions in the following situations:


Alerts

Alerts are a new type of compiler message like Warnings and Errors. An Alert is the same as an Error except that an object file and executable is still produced. This is to allow the disassemblers to be used to help diagnose the cause of the problem. Alerts must not be ignored as the behaviour of the executable will be unpredictable until all alerts have been eliminated.


Preferences

The default Editor Font is Consolas, Size: 9.


Library Modules

GPIO

Additional procedures Set and Reset are more efficient substitutes for Put with a constant state parameter equal to TRUE or FALSE respectively.


Examples

Info

Info (Cortex-M) includes additional information related to the status of the various clocks and PLL.

ByteArrays

ByteArrays is a new example which shows how structured variable parameters can be interpreted as arrays of bytes and vice versa.

VALByteArrays

VALByteArrays is a new example which shows how structured variables can be type cast to arrays of bytes and vice versa using SYSTEM.VAL.

Performance

Performance is a new example which uses the instruction counting feature of Cortex-M3, M4 and M7 to measure the performance of sections of code.


Supported Development Boards

Library modules, example source code and configuration files are included for use with the currently supported development boards.


Problems Fixed

v9.3

v9.2

v9.1