# access fields of a simple struct

# struct details {
#     uint16_t  postcode; // Size = 2 bytes, Offset = 0 bytes
#     uint8_t   wam;      // Size = 1 byte , Offset = 2 bytes
#                         // Hidden 1 byte of "padding"
#                         //  Becase the Offset of each field must be a multiple of the Size of that field
#     uint32_t  zid;      // Size = 4 bytes, Offset = 4 bytes
# }; // Total Size = 8
#    // The Total Size must be a multiple of the Size of the largest field in the struct
#    // More padding will be added to the end of the struct to make this true
#    // (not needed in this example)

# offset in bytes of fields of struct details

OFFSET_POSTCODE   = 0
OFFSET_WAM        = 2
OFFSET_ZID        = 4 # unused padding byte before zid field to ensure it is on a 4-byte boundary

main:

    ### Save values into struct ###

    la   $t0, student           # student.postcode = 2052;
    addi $t1, $t0, OFFSET_POSTCODE
    li   $t2, 2052
    sh   $t2, ($t1)

    la   $t0, student           # student.wam = 95;
    addi $t1, $t0, OFFSET_WAM
    li   $t2, 95
    sb   $t2, ($t1)

    la   $t0, student           # student.zid = 5123456
    addi $t1, $t0, OFFSET_ZID
    li   $t2, 5123456
    sw   $t2, ($t1)

    ### Load values from struct ###

    la   $t0, student           # printf("%d", student.zid);
    addi $t1, $t0, OFFSET_ZID
    lw   $a0, ($t1)
    li   $v0, 1
    syscall

    li   $a0, ' '               #   putchar(' ');
    li   $v0, 11
    syscall

    la   $t0, student           # printf("%d", student.wam);
    addi $t1, $t0, OFFSET_WAM
    lbu  $a0, ($t1)
    li   $v0, 1
    syscall

    li   $a0, ' '               #   putchar(' ');
    li   $v0, 11
    syscall

    la   $t0, student           # printf("%d", student.postcode);
    addi $t1, $t0, OFFSET_POSTCODE
    lhu  $a0, ($t1)
    li   $v0, 1
    syscall

    li   $a0, '\n'              #   putchar('\n');
    li   $v0, 11
    syscall

    li   $v0, 0                 # return 0
    jr   $ra

.data

student:                 # struct details student;
     .space 8			 # 1 unused padding byte included to ensure zid field alligned on 4-byte boundary