Using specialized Magic‐1 instructions - retrotruestory/M1DEV GitHub Wiki

Here's how to leverage specialized Magic-1 instructions for optimized operations:

        .cseg
        .global _fast_block_copy
        .global _atomic_increment
        .global _fast_string_compare

// Fast block copy using hardware memcopy instruction
// void fast_block_copy(void* dst, void* src, unsigned int count)
_fast_block_copy:
        enter   8           
        push    a           
        push    b
        push    c
        
        ld.16   b,12(sp)   ; Load destination to B
        ld.16   a,14(sp)   ; Load source to A
        ld.16   c,16(sp)   ; Load count to C
        
        memcopy            ; Use specialized hardware memcopy
        
        pop     c          
        pop     b
        pop     a
        leave
        ret

// Atomic increment using ldclr instruction
// int atomic_increment(int* ptr)
_atomic_increment:
        enter   4
        push    b
        
        ld.16   b,6(sp)    ; Load pointer to B
        ldclr.8 a,(b)      ; Atomic load and clear
        add.16  a,#1       ; Increment
        st.8    (b),a      ; Store back
        
        pop     b
        leave
        ret

// Fast string compare using hardware string ops
// int fast_string_compare(char* s1, char* s2)
_fast_string_compare:
        enter   4
        push    b
        
        ld.16   a,6(sp)    ; Load s1 to A
        ld.16   b,8(sp)    ; Load s2 to B
        
        strcopy            ; Use hardware string compare
        
        pop     b
        leave
        ret

Then create a C interface:

#ifndef SPECIALIZED_OPS_H
#define SPECIALIZED_OPS_H

// Assembly function declarations
extern void fast_block_copy(void* dst, void* src, unsigned int count);
extern int atomic_increment(int* ptr);
extern int fast_string_compare(char* s1, char* s2);

#endif

Example usage:

#include <stdio.h>
#include "specialized_ops.h"

int main() {
    char src[32] = "Testing Magic-1 specialized ops";
    char dst[32];
    int counter = 0;
    
    // Use hardware-assisted block copy
    fast_block_copy(dst, src, 32);
    
    // Use atomic increment
    atomic_increment(&counter);
    
    // Use hardware string compare
    if (fast_string_compare(src, dst) == 0) {
        printf("Strings match\n");
    }
    
    return 0;
}

Update Makefile:

CC = clcc
AS = m1_as
CFLAGS = -O2
OBJECTS = specialized_ops.o test_specialized.o

all: test_specialized

test_specialized: $(OBJECTS)
    $(CC) $(CFLAGS) -o $@ $(OBJECTS)

%.o: %.s
    $(AS) -o $@ $<

%.o: %.c
    $(CC) $(CFLAGS) -c $<

clean:
    rm -f test_specialized *.o

Key advantages of using specialized Magic-1 instructions:

  • Direct use of hardware memcopy reduces memory operation overhead
  • Atomic operations for thread-safe operations
  • Hardware string operations for faster text processing
  • Reduced instruction count compared to C implementations
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