T9000 Transputer Instruction Set Manual

First Edition 1993
INMOS document number: 72-TRN-240-01
490 Pages

Introduction

This book describes each instruction in the IMS T9000 instruction set and explains the context within which that instruction is used. It is essentially divided into two parts: a narrative that introduces each instruction within a logical group of instructions, and a reference section that gives a code-like specification of each instruction with a cross reference to the narrative.

[For details of the T9000 products and development tools, refer to The T9000 Hardware Reference Manual.]

This is a useful document to all transputer users, but it is aimed in particular at the following.

The high-level programmer in a language such as C might find that, either his particular compiler is limited in certain respects, or a particular piece of code is time critical, and may hence need to write a low-level code sequence. Provided that the compiler/linker system that he is using enables him to write instruction level sequences into his program, he can overcome such difficulties. For this though he needs a good understanding of the capabilities and range of the entire instruction set.

A compiler writer needs to understand the exact action of each instruction in order to write the code generation part of his program.

The writer of a run-time kernel needs to understand the transputer's scheduling mechanism and the instructions which enable him to implement his own scheduling/interrupt scheme.

Similarly the writer of run time support libraries may need to write time critical code at assembly level.

The writer of a debugging tool needs to be able to control low-level context switching (e.g. for implementing breakpoints/single-step) and needs to be able to access and manipulate certain registers and data structures.

Bootstrap code must usually be very compact code and requires some machine specific instructions which are not available in high-level programming languages. For these reasons, a bootstrap program is written at assembly code level and the writer of the program needs to be familiar with the processor's instruction set.

In the narrative part of the book, the art of programming the IMS T9000 is considered subject by subject. Each subject introduces certain instructions. This provides the reader with the purpose for the instructions as they are introduced and describes any environmental issues, such as data structures and register/datastructure pre-conditions. Some of these subjects are of interest to all IMS T9000 users while some are of specific interest to certain categories of reader.

Chapters 3 to 8 should be read by all transputer programmers who are likely to need to know anything about the instruction set. The basic concepts of the IMS T9000 are introduced, including: addressing, instruction representation, processes, registers, communication, and the instructions which are essential for sequential and concurrent programming. These chapters may also be of interest to high-level programmers or system designers who would like a general background on how the IMS T9000 works.

Chapters 9 and 10 are concerned with running code under protection, implementing a memory management scheme, and handling errors or unexpected behaviour. They are of primary interest to operating system writers.

Chapter 11 describes the support for floating-point arithmetic and is of interest to compiler writers, for implementing mathematical run-time library support, and to programmers who are required to write IEEE floating-point exception-handlers.

Chapter 12 discusses how channels are used to communicate between transputer processes. In particular, it describes virtual channels, event channels and resource channels. This information is needed if writing a program to configure a network of transputers (a configurer).

Chapter 13 overviews the various context switches and associated state storage and retrieval mechanisms. These include traps, high-priority process interruption (and return), descheduling and timeslicing. Instructions are described which enable process queues to be manipulated and interrupts/timeslices to be enabled/disabled.

Chapter 14 discusses the various mechanisms available for monitoring the behaviour of a process as it runs, including: breakpointing, watchpointing, single-stepping. The instructions and mechanisms here are of interest to the programmer implementing debugging tools.

Chapter 15 provides a brief overview of the memory architecture and describes the instructions that can be used to invalidate and flush the main cache.

Appendix A is the instruction reference section. It lists all the IMS T9000 instructions in alphabetical order. For each instruction, there is a short English description, a pseudo-code description, and list of pre-conditions, a list of any conditions which may be set by the instruction, and cross reference to the page(s) in the narrative section of the book where the instruction is introduced.

Appendix B provides a tabulated list of all the instructions in ascending order of operation codes. This list is useful for disassembly of instruction code. That is, it provides the user with the information needed to convert from a hex code sequence to an instruction code sequence.

Contents

List of tables

1	Introduction

2	Notation, conventions and terminology

3	An overview
	3.1	Processes
		3.1.1	The occam process model
		3.1.2	Implementation of processes
	3.2	Communication
	3.3	Traps
	3.4	Configuration of control system
	3.5	Instructions and pipelining

4	Addressing and data representation
	4.1	Word address and byte selector
	4.2	Ordering of information
	4.3	Words, objects and signed integers
	4.4	Unaligned address detection

5	Registers, status bits and control bits
	5.1	Machine registers
		5.1.1	State registers
		5.1.2	Other machine registers
	5.2	Process status and control bits
	5.3	The process descriptor and its associated register fields

6	Instruction representation
	6.1	Instruction encoding
		6.1.1	An instruction component
		6.1.2	The instruction data value and prefixing
		6.1.3	Primary Instructions
		6.1.4	Secondary instructions
		6.1.5	Summary of encoding
	6.2	Generating prefix sequences
		6.2.1	Prefixing a constant
		6.2.2	Evaluating minimal symbol offsets

7	Sequential operations
	7.1	Registers
	7.2	Local variables and constants, and stack operations
	7.3	Integer stack evaluation
		7.3.1	Loading operands
		7.3.2	Tables of constants
		7.3.3	Single length signed integer arithmetic
		7.3.4	Single length modulo integer arithmetic
		7.3.5	Unary minus
		7.3.6	Fractional arithmetic
		7.3.7	Bitwise logic and shifts
	7.4	Non-local variables
	7.5	Arrays and subscripts
		7.5.1	Counting bytes and words
		7.5.2	Forming addresses
		7.5.3	Arrays
		7.5.4	Transferring array elements
	7.6	Multiple assignment
	7.7	Comparisons and jumps
		7.7.1	Representation of true and false
		7.7.2	Comparisons
		7.7.3	Implementation of languages with different representations of true and false
		7.7.4	Boolean negation
		7.7.5	Jump and conditional jump
		7.7.6	Evaluation of boolean expressions
		7.7.7	Conditional transfer of control
		7.7.8	Compiling CASE statements
	7.8	Long arithmetic and shifts
		7.8.1	Multiple length addition and subtraction
		7.8.2	Multiple length multiplication and division
		7.8.3	Multiple length shifts
		7.8.4	Normalizing
	7.9	Object length conversion
		7.9.1	Conversion between 8/16-bit object and word representations
		7.9.2	Conversion between single word and double word representations
		7.9.3	General conversion between N-bit object and word representations
	7.10	Replication
	7.11	Procedures
		7.11.1	Adjusting workspace
		7.11.2	Call and return
		7.11.3	Use of (Wptr+0)
		7.11.4	Loading parameters
		7.11.5	The static chain
		7.11.6	Other calling techniques
		7.11.7	Other workspace allocation techniques
	7.12	Functions
		7.12.1	Calling a function
		7.12.2	Single result functions
	7.13	Error checking instructions
	7.14	Device access instructions
	7.15	Specialist instructions
		7.15.1	Two dimensional block move
		7.15.2	Bit manipulation and CRC evaluation

8	Concurrent processes
	8.1	Workspace
		8.1.1	Process workspace data structure
		8.1.2	Size of workspace
	8.2	Scheduling and priority
		8.2.1	The current process, the null process, and scheduling lists
		8.2.2	Descheduling
		8.2.3	Rescheduling after communication
		8.2.4	Clocks and timeslicing
		8.2.5	Priorities and interruption
		8.2.6	Scheduling/descheduling of L-processes
	8.3	Initiation and termination of processes
		8.3.1	Scheduling parallel processes
		8.3.2	Other scheduling instructions
	8.4	Channel communication, synchronization and data-transfer
		8.4.1	Channels
		8.4.2	Synchronization
		8.4.3	Communication
		8.4.4	Implementation of channels
	8.5	Time
		8.5.1	Past and future
		8.5.2	Reading the clock
		8.5.3	Timer input
		8.5.4	Timer lists
	8.6	Semaphores
	8.7	Alternative input
		8.7.1	The occam ALT construct
		8.7.2	The 'alternative sequence'
		8.7.3	Execution of the alternative sequence
		8.7.4	Compiling an ALT statement
		8.7.5	Trapping degenerate alternatives
		8.7.6	Replicated ALT
		8.7.7	PRI ALT
	8.8	Resource channels
		8.8.1	The client-server model
		8.8.2	Resource mechanism and data structures

9	Protection and memory management
	9.1	The mechanism
	9.2	Instruction protection - privileged instructions
	9.3	Address translation, memory protection, and stack extension
	9.4	Regions
	9.5	Region descriptors
	9.6	Registers
	9.7	Data structures
		9.7.1	P-state data structure (PDS)
		9.7.2	Region descriptor data structure (RDDS)
	9.8	Instructions

10	The trap mechanism
	10.1	The trap-handler
		10.1.1	The THDS (trap-handler data structure)
		10.1.2	Sharing a trap-handler data structure
		10.1.3	The null trap-handler
	10.2	State storage and retrieval when a trap is taken
	10.3	Trap causes and signalling of errors
		10.3.1	Trap causes
		10.3.2	Signalling of errors
		10.3.3	Null trap causes
	10.4	Instructions

11	Floating-point instructions
	11.1	IEEE floating-point arithmetic
	11.2	The implementation of IEEE floating-point arithmetic on the IMS T9000
		11.2.1	Formats
		11.2.2	Floating-point operations
		11.2.3	Exceptions
		11.2.4	Not-a-Number representations (NaNs)
		11.2.5	Implementation of underflow
	11.3	Floating-point stack
	11.4	Loading and storing floating-point values
		11.4.1	Loading
		11.4.2	Storing
	11.5	Compiling floating-point expressions
	11.6	Floating-point rounding mode
	11.7	Floating-point arithmetic instructions
		11.7.1	Dyadic operations
		11.7.2	Monadic operations
	11.8	Remainder and range instructions
	11.9	Comparisons
		11.9.1	Comparison instructions
		11.9.2	Implementation of IEEE comparisons
		11.9.3	Some anomalies
	11.10	Class analysis
	11.11	Type conversion
		11.11.1	REAL to REAL conversions
		11.11.2	REAL to INT conversions
		11.11.3	INT to REAL conversions
	11.12	Floating-point state
		11.12.1	Floating-point status word
		11.12.2	Saving the floating-point state
		11.12.3	Instructions for saving and loading floating-point state
	11.13	Exception handling mechanism
		11.13.1	State delivered by floating-point exception - Implementing an IEEE (trap) handler
		11.13.2	Some anomalies
	11.14	Implementation of NaNs

12	Channels
	12.1	Compilation and configuration of channels - an overview
	12.2	External channels
		12.2.1	Virtual channels
		12.2.2	Byte-stream channels
		12.2.3	Event channels
	12.3	Channel states and modes of operation
		12.3.1	Normal channel states
		12.3.2	Resource channel states
		12.3.3	Virtual and event channel activation modes
	12.4	Channel configuration and mapping
		12.4.1	Configuration register instructions
		12.4.2	Configuration registers used for memory mapping
		12.4.3	Virtual link mapping functions
		12.4.4	Packet header labelling
	12.5	Other configuration registers for setting up links and VCP
	12.6	Setting up the virtual link control blocks
		12.6.1	Instructions for setting up a VLCB
		12.6.2	Null header
		12.6.3	An example
	12.7	Resource channels
		12.7.1	Implementation of internal resource channels
		12.7.2	Implementation of external resource channels
		12.7.3	Reverse channel
		12.7.4	Instructions for setting and using the resource mechanism
		12.7.5	Usage of resource channels
	12.8	Resetting and stopping a channel
		12.8.1	Dealing with a communication failure
		12.8.2	Recovering the use of a virtual channel which is in operation
	12.9	Channel instructions according to usage
		12.9.1	Instructions that can be applied to all channels
		12.9.2	Instructions that can be applied to resource channels
		12.9.3	Instructions that can be applied to external channels
		12.9.4	Instructions that can be applied to virtual channels

13	Process state
	13.1	Context switching
	13.2	Partial context switch - descheduling and trapping
		13.2.1	Descheduling and execution of the next process
		13.2.2	Trapping
		13.2.3	Instructions that are used to store and retrieve additional state
	13.3	Full context switch - interruption
	13.4	Restarting an interrupted process
	13.5	Enabling and disabling interruption and timeslicing, and forcing a timeslice
	13.6	Scheduling list and timer list queue manipulation

14	Debugging mechanisms
	14.1	Breakpoints
	14.2	Single-stepping
		14.2.1	Single-stepping a P-process
		14.2.2	Single-stepping an L-process
		14.2.3	Early 'single-step' trap
	14.3	Watchpoints
		14.3.1	Watchpointing a P-process
		14.3.2	Watchpointing an L-process
	14.4	Single-stepping and watchpointing an L-process - some special considerations

15	Cache instructions
	15.1	Workspace cache
	15.2	Main Cache
	15.3	Instructions

A	T9000 instruction set reference guide
	A.1	Introduction
		A.1.1	Instruction name
		A.1.2	Code
		A.1.3	Description
		A.1.4	Definition
		A.1.5	Error signals
		A.1.6	Comments
	A.2	Notation
		A.2.1	The transputer state
		A.2.2	General
		A.2.3	Undefined values
		A.2.4	Data types
		A.2.5	Representing memory
		A.2.6	The configuration subsystem
		A.2.7	Constants
		A.2.8	Operators
		A.2.9	Functions
		A.2.10	Conditions to instructions
	A.3	Instruction set definition
		A
			adc n
			add
			ajw n
			alt
			altend
			altwt
			and
		B
			bcnt
			bitcnt
			bitrevnbits
			bitrevword
			bsub
		C
			call n
			causeerror
			cb
			cbu
			ccnt1
			chantype
			cir
			ciru
			cj n
			crcbyte
			crcword
			cs
			csngl
			csu
			csub0
			cword
		D
			devlb
			devls
			devlw
			devmove
			devsb
			devss
			devsw
			diff
			disc
			disg
			diss
			dist
			div
			dup
		E
			enbc
			enbg
			enbs
			enbt
			endp
			eqc n
			erdsq
		F
			fdca
			fdcl
			fmul
			fpabs
			fpadd
			fpadddbsn
			fpb32tor64
			fpchki32
			fpchki64
			fpdiv
			fpdivby2
			fpdup
			fpeq
			fpexpdec32
			fpexpinc32
			fpge
			fpgt
			fpi32tor32
			fpi32tor64
			fpint
			fpldall
			fpldnladddb
			fpldnladdsn
			fpldnldb
			fpldnldbi
			fpldnlmuldb
			fpldnlmulsn
			fpldnlsn
			fpldnlsni
			fpldzerodb
			fpldzerosn
			fplg
			fpmul
			fpmulby2
			fpnan
			fpnotfinite
			fpordered
			fpr32tor64
			fpr64tor32
			fprange
			fprem
			fprev
			fprm
			fprn
			fprp
			fprtoi32
			fprz
			fpsqrt
			fpstall
			fpstnldb
			fpstnli32
			fpstnlsn
			fpsub
		G
			gajw
			gcall
			goprot
			grant
			gt
			gtu
		I
			ica
			icl
			in
			initvlcb
			insertqueue
			insphdr
			intdis
			intenb
			irdsq
		J
			j n
		L
			ladd
			lb
			lbx
			ldc n
			ldchstatus
			ldcnt
			Idconf
			lddevid
			ldflags
			ldiff
			ldiv
			ldl n
			ldlp n
			Idmemstartval
			Idnl n
			ldnlp n
			ldpi
			ldpri
			ldprodid
			ldresptr
			ldshadow
			Idth
			ldtimer
			lend
			lmul
			ls
			lshl
			lshr
			lsub
			lsum
			lsx
		M
			mint
			mkrc
			move
			move2dall
			move2dinit
			move2dnonzero
			move2dzero
			mul
		N
			nop
			norm
			not
		O
			or
			out
			outbyte
			outword
		P
			pop
			prod
		R
			readbfr
			readhdr
			rem
			resetch
			restart
			ret
			rev
			runp
		S
			sb
			selth
			setchmode
			sethdr
			settimeslice
			shl
			shr
			signal
			ss
			ssub
			startp
			stconf
			stflags
			stl n
			stmove2dinit
			stnl n
			stopch
			stopp
			stresptr
			stshadow
			sttimer
			sub
			sum
			swapbfr
			swapqueue
			swaptimer
			syscall
		T
			talt
			taltwt
			testpranal
			timeslice
			tin
			tret
		U
			unmkrc
		V
			vin
			vout
		W
			wait
			wcnt
			writehdr
			wsub
			wsubdb
		X
			xbword
			xdble
			xor
			xsword
			xword

B	T9000 instruction set sorted by op-code
	B.1	Primary functions
	B.2	Secondary functions
		B.2.1	Instructions encoded without using prefix
		B.2.2	Instructions encoded using prefix
		B.2.3	Instructions encoded using negative prefix

Instruction index

Index

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