Improving the output format

This subroutine to display a vector of words using different strings for first and subsequent elements

# this subroutine prints vectors of words
#
# inputs
#   r0 - start of vector
#   r1 - number of elements to print
#   r2 - pointer to start of string used to print first element
#   r3 - pointer to start of string used to print subsequent elements
#
# no outputs
#
.globl _vprintw
.equ datum_size,4                @ working with 4 byte (32 bit) words
_vprintw:
 stmfd sp!, {r4, r5, r6, r7, lr} @ save registers on the stack
 cmp r1, #0                      @ exit if no elements
 ble last
 mov r4, r0                      @ copy the parameters to locals
 mov r5, r1
 mov r6, r2
 mov r7, r3
 ldr r1, [r4], #datum_size       @ load first vector element to r0 and bump pointer
 mov r0, r6                      @ address of first string to r0
 bl  printf                      @ and print it
 nop
 subs r5, r5, #1                 @ decrement counter
 beq last                        @ and fall out if zero
vprintw_loop:
 ldr r1, [r4], #datum_size       @ load next vector item to r0 and bump pointer
 mov r0, r7                      @ address of subsequent string to r0
 bl  printf                      @ and print it
 subs r5, r5, #1                 @ decrement counter
 bne vprintw_loop                @ and loop if non-zero
last:

 ldmfd sp!, {r4, r5, r6, r7, pc} @ restore registers from stack and return

A simple test harness to use the subroutine is given by

.globl main
.section .rodata
first:
 .asciz "Vector of words - values : %d"
subsequent:
 .asciz ", %d"
final:
 .asciz "\n"
values:
 .word 10, 15, 20, 25, 30, 35, 40, 45, 50, 55, 60
endvalues:
.align 2
.text
main:
        ldr r0, =values
        mov r1, #11
        ldr r2, =first
        ldr r3, =subsequent
        bl _vprintw              @ print the vector elements
        ldr r0, =final
        bl printf                @ print the terminating newline

        mov     r7, #1           @ set r7 to 1 - the syscall for exit
        swi     0                @ then invoke the syscall from linux

bob@poland:~/www/examples$ make test_vprintw
/usr/bin/gcc -gstabs -o test_vprintw test_vprintw.s vprintw.s
bob@poland:~/www/examples$ ./test_vprintw
Vector of words - values : 10, 15, 20, 25, 30, 35, 40, 45, 50, 55, 60
bob@poland:~/www/examples$