calculate routine

calculate:
    sub sp, sp, #16
    push    {fp, lr}
    add fp, sp, #4
    sub sp, sp, #32
    add ip, fp, #4
    stm ip, {r0, r1, r2, r3}
    mov r3, #0
    str r3, [fp, #-8]
    b   .clb1
.clb2:
    ldr r1, .clb3
    ldr r2, [fp, #-8]
    mov r3, r2
    lsl r3, r3, #1
    add r3, r3, r2
    lsl r3, r3, #2
    add r3, r1, r3
    ldr r3, [r3]
    str r3, [fp, #-16]
    ldr r1, .L64
    ldr r2, [fp, #-8]
    mov r3, r2
    lsl r3, r3, #1
    add r3, r3, r2
    lsl r3, r3, #2
    add r3, r1, r3
    add r3, r3, #4
    ldr r3, [r3]
    str r3, [fp, #-20]
    ldr r1, .L64
    ldr r2, [fp, #-8]
    mov r3, r2
    lsl r3, r3, #1
    add r3, r3, r2
    lsl r3, r3, #2
    add r3, r1, r3
    add r3, r3, #8
    ldr r3, [r3]
    str r3, [fp, #-24]
    ldr r3, [fp, #-16]
    ldr r2, [fp, #4]
    mov r1, r2
    mov r0, r3
    bl  __aeabi_fsub
    mov r3, r0
    str r3, [fp, #-16]
    ldr r3, [fp, #-20]
    ldr r2, [fp, #8]
    mov r1, r2
    mov r0, r3
    bl  __aeabi_fsub
    mov r3, r0
    str r3, [fp, #-20]
    ldr r3, [fp, #-24]
    ldr r2, [fp, #12]
    mov r1, r2
    mov r0, r3
    bl  __aeabi_fsub
    mov r3, r0
    str r3, [fp, #-24]
    ldr r2, [fp, #20]
    sub r1, fp, #24
    sub r3, fp, #16
    mov r0, r3
    bl  rotate2d
    ldr r2, [fp, #16]
    sub r1, fp, #24
    sub r3, fp, #20
    mov r0, r3
    bl  rotate2d
    ldr r3, [fp, #-24]
    mov r1, r3
    ldr r0, .clb3+4
    bl  __aeabi_fdiv
    mov r3, r0
    str r3, [fp, #-12]
    ldr r3, [fp, #-16]
    ldr r1, [fp, #-12]
    mov r0, r3
    bl  __aeabi_fmul
    mov r3, r0
    str r3, [fp, #-16]
    ldr r3, [fp, #-20]
    ldr r1, [fp, #-12]
    mov r0, r3
    bl  __aeabi_fmul
    mov r3, r0
    str r3, [fp, #-20]
    ldr r3, [fp, #-16]
    mov r0, r3
    bl  __aeabi_f2iz
    mov r3, r0
    add r3, r3, #160
    str r3, [fp, #-32]
    ldr r3, [fp, #-20]
    mov r0, r3
    bl  __aeabi_f2iz
    mov r3, r0
    rsb r3, r3, #120
    str r3, [fp, #-28]
    ldr r3, [fp, #-8]
    lsl r3, r3, #3
    ldr r2, [fp, #24]
    add r3, r2, r3
    mov r2, r3
    sub r3, fp, #32
    ldm r3, {r0, r1}
    stm r2, {r0, r1}
    ldr r3, [fp, #-8]
    lsl r3, r3, #2
    ldr r2, [fp, #28]
    add r3, r2, r3
    ldr r2, [fp, #-24]
    str r2, [r3]
    ldr r3, [fp, #-8]
    add r3, r3, #1
    str r3, [fp, #-8]
.clb1:
    ldr r3, .clb3+8
    ldr r3, [r3]
    ldr r2, [fp, #-8]
    cmp r2, r3
    blt .clb2
    nop
    sub sp, fp, #4

    pop {fp, lr}
    add sp, sp, #16
    bx  lr