ARM64 Assembly: Arrays and Matrices Explained with QEMU User #raspberrypi #assembly #datastructures
Introduction to Static Data Structures: Arrays and Matrices
Overview of Arrays and Matrices
- The video introduces static data structures, specifically one-dimensional arrays and two-dimensional matrices.
- It utilizes Chemuza, a user space emulator for the ARM 64 architecture, to demonstrate examples without needing a guest system.
Example 45: Array Sum Implementation
- The file
45_array_sum.sis edited using nano, featuring global directives and an external functionittower.
- An array of type word with 10 elements is declared in the data section; a buffer for printing is set up in the BSS section.
- A loop structure is implemented to sum the array values, utilizing registers X4 (counter), X5 (sum), and CBZ for condition checking.
Execution Steps for Array Sum
- Commands are executed in Chemuza to assemble and link object files necessary for execution.
- The final executable prints the sum of the array, which totals 446.
Understanding Matrices at Low Level
Example 46: Matrix Determinant Calculation
- The video transitions to matrices stored sequentially without indices, emphasizing row-major order access through a specific formula.
- In
46_matrix.s, a matrix of size 2x2 is declared along with its buffer; indices are initialized for calculations.
Offset Functionality in Matrix Operations
- An offset function calculates memory addresses based on row-major indexing; results are stored in registers X11 and X12 after invoking this function twice.
Final Steps in Determinant Calculation
- Multiplication operations between matrix values yield intermediate results stored in registers X13 (variable A) and X14 (variable B).
- The determinant is calculated by subtracting these variables; results are prepared for output as character strings before printing.
Conclusion of Video Content
- The final executable named
46_matrixcontains all necessary components to run successfully within Chemuza, yielding an output result of 390.