ARM architecture and programming Learning (2)

Chapter 4 Arm Assembly Language Programming

4.1 arm pseudocommands

There are 6 types of pseudocommands: symbolic definition pseudocommands, data definition pseudocommands, assembly control pseudocommands, framework Description pseudocommands, information reporting pseudocommands, and other pseudocommands.

4.1.1 symbolic definition pseudocommand: used to define variables in arm assembler, assign values to variables, and define Register names.

Gbla, gbll, and gloud declare global variables

Declare local variables by llinoleic, lcll, and lcls

Seta, SETl, and sets assign values to variables

Rlist register list definition name

Register definition name of the CN coprocessor

CP coprocessor definition name

Register definition name with DN and Sn as vfp (floating point Architecture)

FN is the definition name of the FPA floating-point register.

Gbla, gbll, gstrap

Gbla declares a global numeric variable and initializes it to 0.

Gbll declares a Global Logical variable and initializes it to {false}

Gsung declares a global string variable and initializes it as an empty string ""

Example

Gbla objectsize; declare a global numeric variable, initialized to 0

Objectsize Seta 0xff; assign the variable objectsize to 0xff

Space objectsize; reference this variable

Gbll statusb; declare a Global Logical variable statusb

Statusb SETl {true}; assign true to the logic variable statusb

Ltls, lcll, and lcls

Ltls declares a local numeric variable and initializes it to 0.

Lcll declares a local logical variable and initializes it to {false}

Lcls declares a local string variable and initializes it as an empty string.

Seta, SETl, and sets

Seta assigns a value to the numeric variable

SETl assigns values to logical variables

Sets to assign values to string variables

G message; defines a global string variable.

Message sets "hello! "; Assign values to the variable string

Rlist

Rlist defines a name for a general register list

Context rlist {R0-R6, R8, R10-R12, R15}; Define register list name as context

CN

CN defines the name of a coprocessor register

Power CN 6; define the name of the coprocessor register 6 as power

CP

CP defines a name for a coprocessor

Dmu cp 6; Define coprocessor 6 as DMU

DN, Sn

DN is a dual-precision VFP register (numbered 0 ~ 15) Definition name

Sn is a single-precision VFP register (numbered 0 ~ 31) Definition name

Height DN 6; VFP dual-precision register 6 is defined as height

Width Sn 16; the name of VFP single precision register 16 is defined as width

FN

FN is a FPA floating-point register (numbered 0 ~ 7) Definition name

Fat FN 5; Define floating point register 5 as fat

4.1.2 data definition Directive

Ltorg declares the beginning of a Data Buffer Pool

Map defines the first address of a memory table

Field defines the data fields in the memory table

Space allocates a memory unit and initializes it with 0

One-byte memory unit allocated by DCB

DCD and DCDU allocate memory units with one word

Dcdo allocates a memory unit with a single field and is initialized as an offset.

Dcfd and dcfdu allocate one or two-character memory units and initialize them with double-precision floating point data.

DCFS and dcfsu allocate memory units of one word and initialize them with single-precision floating point data.

DCI allocates memory units of one byte.

Dcq and dcqu allocate two-character memory units

Dcw and dcwu allocate a half-Word Memory Unit

Data is no longer used in code segments.

Ltorg

Ltorg is used to declare the beginning of a data buffer pool.

Area example, code, readonly

Start BL func1

Func1; subroutine

; Code

LDR R1, = 0x55555555; LDR R1, [PC, # offest to literal Pool 1]

; Code

MoV PC, LR; end of subroutine

Ltorg; define data buffer pool & 55555555

Data Space 4200; Allocate 4200 bytes of memory units from the current position

End; the default data buffer pool is empty.

Map

Map defines the first address of the memory table, and is used with the field to define the structure of the structured memory table. ^ Is the synonym of map.

Map 0x80, R9; the first address of the memory table is R9 + 0x80

Field

Field defines the data fields in the memory table. # Is a synonym for field. Map and field only define the data structure and do not allocate memory units.

Map 0; memory table's first address is 0

Consta field 4; Consta length is 4 bytes, relative position is 0

Constb field 4; constb length is 4 bytes, relative position is 4

X Field 8; x length 8 bytes, relative position 8

Y Field 8; y length is 8 bytes, relative position is 16

String Field 256; String Length: 256 bytes; relative position: 24

LDR R6, Consta; reference data fields in the memory table

Map 4096; the first address of the memory table is 4096 (0x1000)

Consta field 4; Consta length is 4 bytes, relative position is 0

Constb field 4; constb length is 4 bytes, relative position is 4

X Field 8; x length 8 bytes, relative position 8

Y Field 8; y length is 8 bytes, relative position is 16

String Field 256; String Length: 256 bytes; relative position: 24

MoV r9,# 4096

LDR R5, [R9, constb]; read the data domain constb in the memory table to R5.

In the arm-thumb command, R9 is usually used as the static base address register.

Map 0, R9; the first address of the memory table is R9 + 0

Consta field 4; Consta length is 4 bytes, relative position is 0

Constb field 4; constb length is 4 bytes, relative position is 4

X Field 8; the length of X is 8 bytes, and the relative position is 8

Y Field 8; y is 8 bytes in length and the relative position is 16.

String Field 256; String Length 256, relative position 24

You can use the following commands to easily address data larger than 4 kb.

ADR R9, datastart; the ADR command reads the Pc value or register value to the Register, which is calculated based on the PC value.

LDR R5, constb; equivalent to LDR R5, [R9, #4]

Datastruc space 280; Allocate 280 bytes of memory units

Map datastruc; the first address of the memory table is the memory unit of datastruc.

Consta field 4; Consta length is 4 bytes, relative position is 0

Constb field 4; constb length is 4 bytes, relative position is 4

X Field 8; the length of X is 8 bytes, and the relative position is 8

Y Field 8; y is 8 bytes in length and the relative position is 16.

String Field 256; String Length 256, relative position 24

LDR R5, constb; equivalent to LDR R5, [PC, offest]

When the operand in the field pseudo command is 0, the label indicates the address of the current memory unit.

Space

Space is used to allocate a memory unit and initialize it with 0. % Is a synonym for space.

Datastruc space 1000; Allocate 1000 bytes and initialize the memory unit content to 0

DCB is used to allocate a continuous byte memory. = Is a synonym for DCB

{Label} DCB expr {, expr} {, expr }...

Where:
Label the start address of the memory block.
Expr can be-128 ~ A value or string of 255. The number of bytes allocated by the memory is determined by the number of expr.

Nullstring DCB "Null String", 0; construct a string ending with null

DCD, DCDU, dcdo, dcfd, dcfdu, DCFS, dcfsu, DCI, dcq, dcqu, dcw, and dcwu can be referenced.

4.1.3 Assembly control pseudoinstructions

If, else, And endif

While and Wend

Macro and mend

Mexit

If, else, And endif

If, else, And endif are used to select

If version = "1.0"

; Command

; Pseudoinstructions

Else

; Command

; Pseudoinstructions

Endif

While and Wend

While and Wend Loops

Count Seta 1; set the initial value of the cyclic count variable count to 1.

While count <= 4; number of loops controlled by conut

Count Seta count + 1; Add the cyclic count variable to 1

; Code

Wend

Macro and mend

Macro and mend definition macros

Macro; macro definition starts

$ Label xmac $ P1, $ P2; the macro name is xmac and has two parameters: $ P1 and $ P2.

; Macro label $ lable can be used to construct other label names in the macro definition body

; Code

$ Lable. loop1; Code; $ lable. loop1 indicates the internal label of the macro.

; Code

BGE $ label. loop1

$ Label. loop2; Code

BL $ P1; parameter $ P1 is the name of a subroutine

Bgt $ label. loop2

; Code

ADR $ p2

; Code

Mend; macro definition ends

; Macro calls in the program

ABC xmac subr1, de; calls a macro through the macro name xmac, in which the macro label is ABC,

; Parameter 1 is subr1, parameter 2 is de

; Macro expansion results after the program is compiled

; Code

ABC. loop1; Code; Replace $ label with the actual label value abc

; Code

Bge abc. loop1

ABC. loop2; Code

BL subr1; the actual value of parameter 1 is subr1

; Code

ADR de; the actual value of parameter 2 is de

Mexit

Mexit is used to jump out of the macro

Macro

$ ABC macroabc $ P1, $ p2

; Code

While condition1

; Code

If condition2

; Code

Mexit; jump out of the macro

Else

; Code

Endif

Wend

; Code

Mend

4.1.4 false instructions for information reporting

When the assert condition is invalid, the alarm information is displayed.

Info report information

Opt setting list options

TTL and subt insert titles and subtitles

4.1.6 other pseudocommands

Allgn

Area

Code16 and code32

End

Entry

Equ

Export or global

Extern

Get or include

Import

Incbin

Keep

Nofp

Require

Require8 and perserver8

Rn

Rout

Allgn

Allgn specifies alignment

Area cacheable, code, allgn = 3; specify that the following quality is 8-byte alignment

Rout1; Code

; Code

MoV PC, LR; after the program jumps, it becomes 4-byte alignment

Allgn 8; specify that the following commands are 8-byte aligned

Rout2; Code

Area

Area defines a code segment or data segment

Area example, code, readonly; defines a code segment named example and its attribute is readnoly.

Code16 and code32

Code16 indicates that the subsequent command is the thumb command

Code32 indicates that the subsequent commands are arm commands.

End

End indicates the end of the source program.

Entry

Entry specifies the program entry point.

Equ

Equ is used to get an alias. * is the synonym, which is equivalent to # define in C.

ABCD equ 2; Define ABCD to represent 2

Addr1 equ 0x1c, code32; defines addr1 as the absolute address 0x1c, and this command is an arm command

Export and global

Export declares that a symbol can be referenced by other files, which is equivalent to declaring a global variable. Global is a synonym for export.

Area example, code, readonly

Export doadd; the following function name doadd can be referenced by other source files

Doadd add r0, R0, r1

Extern

Extern declares a symbol defined in other source files.

Area example, code, readonly

Extern _ cpp_initialize [Weak]; if the C ++ library is connected, the function _ cpp_initialize address is read.

LDR r0, _ cpp_initialize

CMP r0, 0;

Beq nocplusplus; skip to nocplusplus if the C ++ library is not connected

Get and include

Get includes a file to the current file. Include is a get synonym.

Area example, code, readnoly

Get file1.s; contains the source file file1.s

Get C:/project file/file2.s; contains the source file file2.s, which can contain spaces in the path

Import

Import external definition symbols

Incbin

Incbin includes the file into the current file, but the contained file is not assembled.

Area example, code, readonly

Incbin file1.dat; contains the file file1.dat

Incbin C:/projecfile/file2.txt contains the file file2.txt, which cannot contain spaces.

Keep

Keep includes local symbols in the symbol table of the target file.

Nofp

Nofp disables floating-point operations

Prequire

Dependencies between specified segments in prequire

Require8 and preserver8

Require8 requires 8-byte data stack alignment in the current Code

Preserve8 requires 8-byte data stack alignment in the current Code

Rn

Rn defines a register name, that is, changing the name.

Rout

Rout defines the valid range of local variables