Semiconductor & Computer Engineering
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Difference between revisions of "arm/armv1"
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== Registers == | == Registers == | ||
| − | There are 16 [[general purpose registers|general purpose]] 32-bit registers. With the exception of {{arm|R15|register 15}}, all registers are orthogonal with no specific designated purpose. | + | There are 16 [[general purpose registers|general purpose]] 32-bit registers. With the exception of {{arm|R15|register 15}} and 14, all registers are orthogonal with no specific designated purpose. |
== Instruction Listing == | == Instruction Listing == | ||
Revision as of 00:43, 28 June 2017
ARMv1 is the first ARM instruction set version. Introduced with the ARM1 on April 26 1985, the ARMv1 defines a 32-bit ISA along with 26-bit addressing space. The ARMv1 was only implemented by the ARM1 and was replaced soon after by the ARM2. Only a few hundred of those chips were ever fabricated.
Overview
The ARMv1 is a simple architecture consisting of mostly simple operations along with a handful of complex ones. Each instruction is 32-bit in size and operates on two 32-bit operands. There is a 24-bit program counter allowing for a 26-bit address space of up to 64 MiB of memory.
Registers
There are 16 general purpose 32-bit registers. With the exception of register 15 and 14, all registers are orthogonal with no specific designated purpose.
Instruction Listing
The ARMv1 ISA has 45 operations under 23 mnemonics. The ARMv1 is broken down into 8 classes of instruction:
- Movement Instructions
- Load Instructions
- Store Instructions
- Arithmetic Instructions
- Logical Instructions
- Comparison Instructions
- Branch Instructions
- Miscellaneous Instructions
| ARMv1 ISA | ||||
|---|---|---|---|---|
| Mnemonic | Syntax | Description | Action | |
| Movement Instructions Movement instructions move data between registers and operands. | ||||
| MOV | MOV<cond>{S} Rd, #imm | Move value immed | Rd = immed | |
| MOV | MOV<cond>{S} Rd, Rm, {, <shift>} | Move value | Rd = {shifted Rm} | |
| MVN | MVN<cond>{S} Rd, #imm | Move NOT value immed | Rd = ¬immed | |
| MVN | MVN<cond>{S} Rd, Rm, {, <shift>} | Move NOT value | Rd = ¬{shifted Rm} | |
| Load Instructions Load instructions move the content of memory addresses into registers. | ||||
| LDM | LDM<cond><type> Rn{!}, <reglist>{^} | Load multiple | addr = Rn for each Rd in {reglist}: Rd = [addr] update address based on {type} | |
| LDR | LDR<cond>{B} Rd, [Rn {, #imm}]{!} | Load register immed | Rd = [Rn + imm] If !: Rn = Rn + imm | |
| LDR | LDR<cond>{B} Rd, [Rn, Rm {, <shift>}]{!} | Load register | Rd = [Rn + {shifted Rm}] If !: Rn = Rn + {shifted Rm}] | |
| LDR | LDR<cond>{B}{T} Rd, [Rn], #imm | Load register, post index | Rd = [Rn] Rn = Rn + imm | |
| LDR | LDR<cond>{B}{T} Rd, [Rn], Rm {, <shift>} | Load register, post index | Rd = [Rn] Rn = Rn + {shifted Rm} | |
| Store Instructions Store instructions moves the values from registers into memory. | ||||
| STM | STM<cond><type> Rn{!}, <reglist>{^} | Store multiple | addr = Rn for each Rd in {reglist}: [addr] = Rd update address based on {type} | |
| STR | STR<cond>{B} Rd, [Rn {, #imm}]{!} | Store register immed | [Rn + imm] = Rd If !: Rn = Rn + imm | |
| STR | STR<cond>{B} Rd, [Rn, Rm {, <shift>}]{!} | Store register | [Rn + {shifted Rm}] = Rd If !: Rn = Rn + {shifted Rm}] | |
| STR | STR<cond>{B}{T} Rd, [Rn], #imm | Store register, post index | [Rn] = Rd Rn = Rn + imm | |
| STR | STR<cond>{B}{T} Rd, [Rn], Rm {, <shift>} | Store register, post index | [Rn] = Rd Rn = Rn + {shifted Rm} | |
| Arithmetic Instructions Arithmetic instructions perform basic mathematical operations on two operands. | ||||
| ADC | ADC<cond>{S} Rd, Rn, #imm | Add and carry immed | Rd = Rn + imm + C | |
| ADC | ADC<cond>{S} Rd, Rn, Rm{, <shift>} | Add and carry | Rd = Rn + {shifted Rm} + C | |
| ADD | ADD<cond>S Rd, Rn, #imm | Add immed | Rd = Rn + imm | |
| ADD | ADD<cond>S Rd, Rn, Rm{, <shift>} | Add | Rd = Rn + {shifted Rm} | |
| RSB | RSB<cond>S Rd, Rn, #imm | Reverse subtract immed | Rd = imm - Rn | |
| RSB | RSB<cond>S Rd, Rn, Rm{, <shift>} | Reverse subtract | Rd = {shifted Rm} - Rn | |
| RSC | RSB<cond>S Rd, Rn, #imm | Reverse subtract with carry immed | Rd = imm - Rn - ¬C | |
| RSC | RSB<cond>S Rd, Rn, Rm{, <shift>} | Reverse subtract with carry | Rd = {shifted Rm} - Rn - ¬C | |
| SBC | SBC<cond>{S} Rd, Rn, #imm | Subtract with carry immed | Rd = Rn - imm - ¬C | |
| SBC | SBC<cond>{S} Rd, Rn, Rm{, <shift>} | Subtract with carry | Rd = Rn - {shifted Rm} - ¬C | |
| SUB | SUB<cond>{S} Rd, Rn, #imm | Subtract immed | Rd = Rn - imm | |
| SUB | SUB<cond>{S} Rd, Rn, Rm{, <shift>} | Subtract | Rd = Rn - {shifted Rm} | |
| Logical Instructions Logical instructions perform logical bitwise operations on operands. | ||||
| AND | AND<cond>{S} Rd, Rn, #imm | AND immed | Rd = Rn & imm | |
| AND | AND<cond>{S} Rd, Rn, Rm{, <shift>} | AND | Rd = Rn & {shifted Rm} | |
| BIC | BIC<cond>{S} Rd, Rn, #imm | Bit clear immed | Rd = Rn & ¬imm | |
| BIC | BIC<cond>{S} Rd, Rn, Rm{, <shift>} | Bit clear | Rd = Rn & ¬Rm | |
| EOR | EOR<cond>{S} Rd, Rn, #imm | Exclusive OR immed | Rd = Rn ⊕ imm | |
| EOR | EOR<cond>{S} Rd, Rn, Rm{, <shift>} | Exclusive OR | Rd = Rn ⊕ {shifted Rm} | |
| ORR | ORR<cond>{S} Rd, Rn, #imm | Logical OR immed | Rd = Rn ∥ imm | |
| ORR | ORR<cond>{S} Rd, Rn, Rm{, <shift>} | Logical OR | Rd = Rn ∥ {shifted Rm} | |
| Comparison Instructions Comparison instructions compare two values and set appropriate status flags. | ||||
| CMN | CMN<cond> Rn, #imm | Compare negative immed | CPSR flags set on (Rn + imm) | |
| CMN | CMN<cond> Rn, Rm{, <shift>} | Compare negative | CPSR flags set on (Rn + {shifted Rm}) | |
| CMP | CMP<cond> Rn, #imm | Compare immed | CPSR flags set on (Rn - imm) | |
| CMP | CMP<cond> Rn, Rm{, <shift>} | Compare | CPSR flags set on (Rn - {shifted Rm}) | |
| TEQ | TEQ<cond> Rn, #imm | Test equality immed | CPSR flags set on (Rn ⊕ imm) | |
| TEQ | TEQ<cond> Rn, Rm{, <shift>} | Test equality | CPSR flags set on (Rn ⊕ {shifted Rm}) | |
| TST | TST<cond> Rn, #imm | Test bits immed | CPSR flags set on (Rn & imm) | |
| TST | TST<cond> Rn, Rm{, <shift>} | Test bits | CPSR flags set on (Rn & {shifted Rm}) | |
| Branch Instructions Branch instructions order instruction processing to start elsewhere conditionally or unconditionally. | ||||
| B | B<cond> imm | Branch relative | PC = PC + address | |
| BL | BL<cond> imm | Branch and link relative | LR = RET PC = PC + address | |
| Miscellaneous Instructions Any instruction that doesn't belong anywhere else. | ||||
| SWI | SWI<cond> imm | Software interrupt | LR = RET Execute SWI vector in supervisor mode | |
Multiplication and Floating Point
ARMv1 does not have support for multiplication. Software that requires multiplication will have to resort to a software implementation (e.g., Shift-and-Add Multiplication). This was considerably slow and was consequently added in later ARM versions. Likewise there was no support for hardware floating point or an ability to do such operations on an external FPU coprocessor.