assembler (m1_as) - retrotruestory/M1DEV GitHub Wiki

Here are all available Magic-1 commands and instructions:

Load/Store Instructions

ld.8/16    - Load 8/16-bit value
st.8/16    - Store 8/16-bit value 
ldclr      - Load and clear (for semaphores)
push       - Push to stack
pop        - Pop from stack
memcopy    - Block copy
tosys      - Copy from user to system space
fromsys    - Copy from system to user space
ldcode     - Load from code space
stcode     - Store to code space

Address/Register Operations

lea        - Load effective address
copy       - Copy between registers
sex        - Sign extend
PTB        - Page Table Base operations
MSW        - Machine Status Word operations

Arithmetic Operations

add.8/16   - Add 8/16-bit
sub.8/16   - Subtract 8/16-bit
and.8/16   - Logical AND 8/16-bit
or.8/16    - Logical OR 8/16-bit
xor.16     - Logical XOR 16-bit
shl.16     - Shift left
shr.16     - Shift right
vshl.16    - Variable shift left
vshr.16    - Variable shift right
adc.16     - Add with carry
sbc.16     - Subtract with carry

Control Flow

br         - Branch unconditional
br.eq      - Branch if equal
br.ne      - Branch if not equal
br.lt      - Branch if less than
br.le      - Branch if less/equal
br.gt      - Branch if greater than
br.ge      - Branch if greater/equal
br.ltu     - Branch if less than (unsigned)
br.leu     - Branch if less/equal (unsigned)
call       - Call subroutine
ret        - Return from subroutine
reti       - Return from interrupt

System Operations

halt       - Halt processor
syscall    - System call
bkpt       - Breakpoint
trapo      - Trap on overflow
wcpte      - Write code page table entry
wdpte      - Write data page table entry
enter      - Function prologue
leave      - Function epilogue

Comparison Instructions

cmp.8/16   - Compare 8/16-bit
cmpb.eq    - Compare and branch if equal
cmpb.ne    - Compare and branch if not equal
cmpb.lt    - Compare and branch if less than
cmpb.le    - Compare and branch if less/equal

Bit Operations

bset       - Set bit
bclr       - Clear bit
test       - Test bit

This instruction set provides a complete environment for systems programming, with support for:

• Memory management
• Stack operations
• Arithmetic/logic operations
• Control flow
• System calls/privileged operations
• Bit manipulation

Here's a detailed overview of how M1 assembly code works:

Basic M1 Assembly Syntax

// Basic instruction format
label:    instruction    operands    ; comment

// Example with data definition
        .cseg           ; Code segment
        .global _main   ; Global label declaration
_main:  
        enter   4       ; Function prologue
        ld.16   a,#1234 ; Load immediate value

Key Assembler Directives

.cseg     # Start code segment
.dseg     # Start data segment
.global   # Declare global symbol
.defb     # Define byte
.defw     # Define word
.equ      # Define constant

Common Address Modes

ld.8  a,#42        # Immediate value
ld.16 a,(dp)       # Direct addressing
ld.8  a,(b)        # Register indirect
ld.16 a,4(sp)      # Base + displacement

Example Function

        .global _example
_example:
        enter   8           ; Setup stack frame
        push    a           ; Save register
        ld.16   a,6(sp)    ; Load parameter
        add.16  a,#1       ; Add 1
        pop     a          ; Restore register
        leave              ; Restore stack frame
        ret               ; Return

The assembler supports:

• Labels and symbols
• Multiple segments (code, data)
• Local and global scope
• Expressions in operands
• Relocatable code generation
• Symbol table generation