// Recursive diamond by George Karlos
//
// print a pyramid of characters starting from input char and
// going down to ascii 0x31 (1) using nested recursions
//

.constant
    NEWLINE 0xA
    OBJREF 0xDEAD
    ZERO 0x30
    ONE 0x31
    SPACE 0x20
.end-constant

.main
    LDC_W OBJREF
prompt:
    IN

    DUP
    LDC_W ZERO
    ISUB
    IFLT prompt

    LDC_W ONE
    INVOKEVIRTUAL diamond

done:
    HALT
.end-main

.method diamond(n,i)
.var
backupn
backupi
.end-var

    ILOAD n
    LDC_W ZERO
    SWAP
    ISUB
    IFEQ return

    //print empty spaces
    LDC_W OBJREF
    LDC_W SPACE
    ILOAD n
    INVOKEVIRTUAL printntimes

    //print char
    LDC_W OBJREF
    ILOAD n
    ILOAD i
    INVOKEVIRTUAL printntimes

    LDC_W NEWLINE
    OUT

    ILOAD n
    ISTORE backupn
    IINC n -1
    ILOAD i
    ISTORE backupi
    IINC i 2

    LDC_W OBJREF
    ILOAD n
    ILOAD i
    INVOKEVIRTUAL diamond

    //dont print 1's again
    ILOAD backupn
    LDC_W ONE
    ISUB
    IFEQ return

    //print empty spaces
    LDC_W OBJREF
    LDC_W SPACE
    ILOAD backupn
    INVOKEVIRTUAL printntimes


    //print char
    LDC_W OBJREF
    ILOAD backupn
    ILOAD backupi
    INVOKEVIRTUAL printntimes

    LDC_W NEWLINE
    OUT

return:
    BIPUSH 0x1 //Just a return value
    IRETURN
.end-method


.method printntimes(c,n)
    ILOAD n
    LDC_W ZERO
    SWAP
    ISUB
    IFEQ return

    ILOAD c
    OUT

    IINC n -1
    LDC_W OBJREF
    ILOAD c
    ILOAD n
    INVOKEVIRTUAL printntimes

return:
    BIPUSH 0x2 //Just a return value
    IRETURN

.end-method