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Created page with 'Category:Assembler == Registers == === General-Purpose Registers === The aarch64 registers are named: * r0 through r30 - for 64-bit-wide access * w0 through w30 - for 32-b…'
[[Category:Assembler]]
== Registers ==
=== General-Purpose Registers ===
The aarch64 registers are named:
* r0 through r30 - for 64-bit-wide access
* w0 through w30 - for 32-bit-wide access (same registers - upper 16 bits are cleared on load)
Register '31' is one of two registers depending on the instruction context:
* For instructions dealing with the stack, it is the stack pointer, named rsp
* For all other instructions, it is a "zero" register, which returns 0 when read and discards data when written - written as rzr
Usage during syscall/function call:
* '''r0-r7 are used for arguments and return values'''
* '''For syscalls, the syscall number is in r8'''
* '''r9-r15 are for temporary values (may get trampled)'''
* r16-r18 are used for intra-procedure-call and platform values (avoid)
* '''The called routine is expected to save r19-r28'''
* r29 and r30 are used as the frame register and link register (avoid)
=== Floating-Point and SIMD Registers ===
x86_64 also defines a set of large registers for floating-point and single-instruction/multiple-data (SIMD) operations. For details, refer to the Intel or AMD documentation.
== Instructions ==
=== Starter Kit ===
These instructions are sufficient to complete the [[SPO600 Assembler Lab]]:
add r0,r1,r2 // load r0 with r1+r2
add r0,r1,99 // load r0 with r1+99
adr r0,''label'' // load r0 with the address ''label'' (this actually calculates an address from the [[Register#Program Counter|PC]] plus an offset)
beq ''label'' // branch to label if equal
bne ''label'' // branch to label if not equal
blt ''label'' // branch to label if less
bgt ''label'' // branch to label if greater
cmp r0,r1 // compare register r0 with register r1
cmp r0,99 // compare the number 99 with register r0
ldr r0,[r1,0] // load register r0 from the address pointed to by (r1 + (0 * ''size'')) where ''size'' is 8 bytes for 64-bit stores, 4 bytes for 32-bit stores
ldr w0,[r1,0] // like ldr but reads one byte only - note the use of w0 instead of r0 for the source register name
ldur r0,[r1,0] // load register r0 from the address pointed to by (r1 + 0) - the mnemonic means "load ''unscaled'' register"
mov r0,r1 // move data from r1 to r0
mov r0,99 // load r0 with 99 (only certain immediate values are possible)
str r0,[r1,0] // store register r0 to address pointed to by (r1 + (0 * ''size'')) where ''size'' is 8 bytes for 64-bit stores
strb w0,[r1,0] // like str but writes one byte only - note the use of w0 instead of r0 for the source register name
stur r0,[r1,0] // store register r0 to the address pointed to by (r1 + 0) - the mnemonic means "store ''unscaled'' register"
mov (%r10),%r11 // move data from address pointed to by r10 to r10
msub r0,r1,r2,r3 // load r0 with r3-(r1*r2) (useful for calculating remainders)
madd r0,r1,r2,r3
mul r0,r1,r2 // load r0 with r1*r2 (actually an alias - see ARM ARM)
push r0 // push r0 onto the stack
pop r0 // pop r0 off the stack
udiv r0,r1,r2 // unsigned - divide r1 by r2, places quotient into r0 - remainder is not calculated (use msub)
== References ==
* Instruction Set and Software Developer Manual: http://infocenter.arm.com/help/index.jsp?topic=/com.arm.doc.genc010197a/index.html
* Procedure call reference: http://infocenter.arm.com/help/topic/com.arm.doc.ihi0055b/IHI0055B_aapcs64.pdf
== Registers ==
=== General-Purpose Registers ===
The aarch64 registers are named:
* r0 through r30 - for 64-bit-wide access
* w0 through w30 - for 32-bit-wide access (same registers - upper 16 bits are cleared on load)
Register '31' is one of two registers depending on the instruction context:
* For instructions dealing with the stack, it is the stack pointer, named rsp
* For all other instructions, it is a "zero" register, which returns 0 when read and discards data when written - written as rzr
Usage during syscall/function call:
* '''r0-r7 are used for arguments and return values'''
* '''For syscalls, the syscall number is in r8'''
* '''r9-r15 are for temporary values (may get trampled)'''
* r16-r18 are used for intra-procedure-call and platform values (avoid)
* '''The called routine is expected to save r19-r28'''
* r29 and r30 are used as the frame register and link register (avoid)
=== Floating-Point and SIMD Registers ===
x86_64 also defines a set of large registers for floating-point and single-instruction/multiple-data (SIMD) operations. For details, refer to the Intel or AMD documentation.
== Instructions ==
=== Starter Kit ===
These instructions are sufficient to complete the [[SPO600 Assembler Lab]]:
add r0,r1,r2 // load r0 with r1+r2
add r0,r1,99 // load r0 with r1+99
adr r0,''label'' // load r0 with the address ''label'' (this actually calculates an address from the [[Register#Program Counter|PC]] plus an offset)
beq ''label'' // branch to label if equal
bne ''label'' // branch to label if not equal
blt ''label'' // branch to label if less
bgt ''label'' // branch to label if greater
cmp r0,r1 // compare register r0 with register r1
cmp r0,99 // compare the number 99 with register r0
ldr r0,[r1,0] // load register r0 from the address pointed to by (r1 + (0 * ''size'')) where ''size'' is 8 bytes for 64-bit stores, 4 bytes for 32-bit stores
ldr w0,[r1,0] // like ldr but reads one byte only - note the use of w0 instead of r0 for the source register name
ldur r0,[r1,0] // load register r0 from the address pointed to by (r1 + 0) - the mnemonic means "load ''unscaled'' register"
mov r0,r1 // move data from r1 to r0
mov r0,99 // load r0 with 99 (only certain immediate values are possible)
str r0,[r1,0] // store register r0 to address pointed to by (r1 + (0 * ''size'')) where ''size'' is 8 bytes for 64-bit stores
strb w0,[r1,0] // like str but writes one byte only - note the use of w0 instead of r0 for the source register name
stur r0,[r1,0] // store register r0 to the address pointed to by (r1 + 0) - the mnemonic means "store ''unscaled'' register"
mov (%r10),%r11 // move data from address pointed to by r10 to r10
msub r0,r1,r2,r3 // load r0 with r3-(r1*r2) (useful for calculating remainders)
madd r0,r1,r2,r3
mul r0,r1,r2 // load r0 with r1*r2 (actually an alias - see ARM ARM)
push r0 // push r0 onto the stack
pop r0 // pop r0 off the stack
udiv r0,r1,r2 // unsigned - divide r1 by r2, places quotient into r0 - remainder is not calculated (use msub)
== References ==
* Instruction Set and Software Developer Manual: http://infocenter.arm.com/help/index.jsp?topic=/com.arm.doc.genc010197a/index.html
* Procedure call reference: http://infocenter.arm.com/help/topic/com.arm.doc.ihi0055b/IHI0055B_aapcs64.pdf