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.syntax unified
.cpu cortex-m0plus
.thumb
.equ CLOCKS_BASE, 0x40008000
.equ CLK_REF_CTRL_OFST, 0x30
.equ CLK_SYS_CTRL_OFST, 0x3c
.equ CLK_PERI_CTRL_OFST, 0x48
.type setup_clocks, %function
.global setup_clocks
setup_clocks:
ldr r1, =CLOCKS_BASE
// Reference clock
movs r0, 0x2 // src = xosc
str r0, [r1, CLK_REF_CTRL_OFST]
// System clock
movs r0, 0x0 // src = clk_ref
str r0, [r1, CLK_SYS_CTRL_OFST]
// Peripheral clock
movs r0, 1 // set enable
lsls r0, 11
adds r0, 0x4 << 5 // src = xosc
str r0, [r1, CLK_PERI_CTRL_OFST]
bx lr
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