60 lines
No EOL
3.1 KiB
NASM
60 lines
No EOL
3.1 KiB
NASM
; ========================================================================================
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; DATATRANSFER.asm - Memory-Based Data Transfer Operations Demonstration
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; ========================================================================================
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; This program demonstrates how to transfer data from memory locations to registers
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; using ARM load instructions. It shows the difference between loading an address
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; and loading the actual data stored at that address.
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AREA RESET,DATA,READONLY ; Define a read-only data section for the vector table
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EXPORT __Vectors ; Export the vector table for external linking
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__Vectors ; Start of the vector table
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DCD 0x10001000 ; Stack pointer initial value (points to top of stack)
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DCD Reset_Handler ; Address of the reset handler (program entry point)
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ALIGN ; Ensure proper alignment for the next section
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AREA mycode,CODE,READONLY ; Define the code section as read-only
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ENTRY ; Mark the entry point of the program
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EXPORT Reset_Handler ; Export the reset handler function
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; ========================================================================================
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; Reset_Handler - Main program execution
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; ========================================================================================
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; This function demonstrates memory data transfer operations:
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; 1. Load the address of a data array into a register
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; 2. Load the actual data from that memory location
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; 3. Load an immediate negative value for comparison
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Reset_Handler
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; Step 1: Load memory address into register
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; LDR with = syntax loads the address of the SRC array into R0
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; This gives us a pointer to the beginning of the data array
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LDR R0, =SRC ; R0 = address of SRC array
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; Step 2: Load data from memory location
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; LDR with [] syntax loads the actual data stored at the address in R0
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; This reads the first 32-bit word from the SRC array (0x12345678)
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LDR R1, [R0] ; R1 = data at address in R0 (first element of SRC)
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; Step 3: Load immediate negative value
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; MOV instruction loads the immediate negative value -8 into R5
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; This demonstrates mixing memory loads with immediate loads
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MOV R5, -8 ; R5 = -8 (immediate negative value)
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; Step 4: Program termination
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; Create an infinite loop to stop program execution
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STOP
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B STOP ; Branch to STOP label (infinite loop)
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ALIGN ; Ensure proper alignment for data section
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; ========================================================================================
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; Data Section - Source data array
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; ========================================================================================
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; SRC array contains three 32-bit words in hexadecimal format:
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; - First word: 0x12345678 (305419896 in decimal)
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; - Second word: 0xABCDEF55 (2882400341 in decimal)
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; - Third word: 0x55 (85 in decimal)
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SRC DCD 0x12345678, 0xABCDEF55, 0x55
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END ; End of the assembly program
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