#define bob 10
.equ bob, 10

unsigned int ted;
ted:
.word 0

unsigned int alice = 42;
alice:
.word 42

.text

    .equ x, 123
    mov $x, %eax
    /* eax == 123 */

    .equ x, 456
    mov $x, %eax
    /* eax == 456 */

as --32 -o main.o main.S
objdump -Sr main.o

00000000 <.text>:
  0:   b8 7b 00 00 00          mov    $0x7b,%eax
  5:   b8 c8 01 00 00          mov    $0x1c8,%eax

readelf -s main.o

Num:    Value  Size Type    Bind   Vis      Ndx Name
  4: 000001c8     0 NOTYPE  LOCAL  DEFAULT  ABS x

g_pfnVectors:
  .word  _estack
  .word  Reset_Handler
  .word  NMI_Handler
  .word  HardFault_Handler
  .word  MemManage_Handler
  ...