# --------------------------------------------
# FUNCTION: make_coordinate_buffer
# PURPOSE : allocate memory for n coordinate tuples (16 bytes each)
# INPUTS  : rdi = number of coordinates
# OUTPUTS : rax = pointer to allocated coordinate buffer
# CLOBBERS: rax, rdi, r11
# --------------------------------------------

.globl make_coordinate_buffer
.type make_coordinate_buffer, @function
make_coordinate_buffer:
    imulq $16, %rdi       # multiply n by 16 
    call allocate        # allocate total bytes
    ret


# --------------------------------------------
# FUNCTION: build_pointer_buffer
# PURPOSE : build a buffer of pointers to coordinate tuples
# INPUTS  : rdi = coordinate buffer, rsi = number of tuples
# OUTPUTS : rax = pointer buffer
# CLOBBERS: rax, rcx, rdx, r8, r9
# --------------------------------------------

.globl build_pointer_buffer
.type build_pointer_buffer, @function
build_pointer_buffer:
    movq %rdi, %r8              # save coordinate buffer pointer in r8
    movq %rsi, %rax
    imulq $8, %rax              # 1 pointer per coordinate / each pointer 8 bytes
    movq %rax, %rdi             # argument for allocate
    call allocate               # pointer buffer -> rax
    movq %rax, %r9              # save pointer buffer in r9

    movq $0, %rcx               # index = 0
pointer_loop:
    cmpq %rsi, %rcx             # # if rcx >= n, done
    jge done

    movq %rcx, %rdx
    imulq $16, %rdx             # 16 byte jumps / every pair of coordinates = 8 bytes + 8 bytes
    addq %r8, %rdx              # rdX = coord_buffer + offset
    movq %rdx, (%r9,%rcx,8)     # store pointer in pointer buffer / 8 byte jumps here, every pointer is 8 bytes

    incq %rcx
    jmp pointer_loop

done:
    movq %r9, %rax           # return pointer buffer
    ret