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What are the ARM instruction formats?
The Arm architecture supports three instruction sets: A64, A32 and T32. The A64 and A32 instruction sets have fixed instruction lengths of 32-bits. The T32 instruction set was introduced as a supplementary set of 16-bit instructions that supported improved code density for user code.
What is opcode in ARM?
As an example, the 32-bit opcode 111000000100100010010000000000100 instructs the ARM processor to add the contents of R1 and R2, place the result in R4, and to execute the instruction unconditionally, and then update the ALU status bits. When written as a binary number, an Opcode is also referred to as “machine code”.
What is ARM branch instructions?
In the ARM instruction set, a data-processing instruction that targets the PC behaves as a branch instruction. For more information, see Data-processing instructions. In the ARM and Thumb instruction sets, a load instruction that targets the PC behaves as a branch instruction.
What is RSB instruction in ARM?
The RSB instruction subtracts the value in Rn from the value of Operand2 . This is useful because of the wide range of options for Operand2 . Use ADC and SBC to synthesize multiword arithmetic, see Multiword arithmetic examples.
What is ADC in ARM?
Analog to Digital Converter(ADC) is used to convert analog signal into digital form. LPC2148 has two inbuilt 10-bit ADC i.e. ADC0 & ADC1. ADCs in LPC2148 use Successive Approximation technique to convert analog signal into digital form.
Is the RSB instruction available in ARMv6T2?
The deprecation of SP and PC in ARM instructions is only in ARMv6T2 and above. If S is specified, the RSB instruction updates the N, Z, C and V flags according to the result. The following forms of this instruction are available in Thumb code, and are 16-bit instructions: Rd and Rn must both be Lo registers.
What does the RSB instruction do in Assembly?
The RSB instruction is a Reverse SuBtract without carry. The documentation indicates the syntax: RSB {S} {cond} {Rd}, Rn, Operand2 The following usage can then be explained:
Is the RSB instruction available in Thumb code?
If S is specified, the RSB instruction updates the N, Z, C and V flags according to the result. The following forms of this instruction are available in Thumb code, and are 16-bit instructions:
Can you use SP in an ASR instruction?
You can use SP in the ASR ARM instruction but this is deprecated in ARMv6T2 and above. You cannot use PC in instructions with the ASR {S} {cond} Rd, Rm, Rs syntax.