5.4.2. Accessing the FPU registers

Access to the FPU registers is controlled the CPACR. See Coprocessor Access Control Register for information on this register.

To use the FPU, you must define the CPACR and Floating-Point Exception Register (FPEXC) registers to enable the FPU:

  1. Set the CPACR for access to CP10 and CP11 (the FPU coprocessors):

    LDR r0, =(0xF << 20)
    MCR p15, 0, r0, c1, c0, 2
  2. Set the FPEXC EN bit to enable the FPU:

    MOV r3, #0x40000000 
    VMSR FPEXC, r3
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