83 lines
1.3 KiB
ArmAsm
83 lines
1.3 KiB
ArmAsm
.syntax unified
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#ifndef NRF51
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// put it in RAM
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.section .data.neopixel_send_buffer_nrf52
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.global neopixel_send_buffer_nrf52
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.thumb
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.type neopixel_send_buffer_nrf52, %function
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neopixel_send_buffer_nrf52:
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push {r4,r5,r6,r7,lr}
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lsrs r7, r1, #20 // r7 - brightness
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ands r1, #0xff
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movs r4, #1
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lsls r1, r4, r1 // r1 - mask
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mov r4, r2 // ptr
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mov r5, r3 // len
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mov r3, r0 // port+0x500
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b .start
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.nextbit:
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str r1, [r3, #0x8] // pin := hi
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movs r2, #8
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tst r6, r0
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it eq
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movseq r2, #3
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.d1:
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subs r2, #1
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bne .d1
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str r1, [r3, #0xC] // pin := lo
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movs r2, #4
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tst r6, r0
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it eq
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movseq r2, #6
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lsrs r6, r6, #1 // r6 >>= 1
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beq .reload
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nop
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nop
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nop
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.d0:
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subs r2, #1
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bne .d0
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b .nextbit
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.reload:
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subs r2, #2 // offset following operations
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.d2:
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subs r2, #1
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bne .d2
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// not just a bit - need new byte
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adds r4, #1 // r4++
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subs r5, #1 // r5--
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ble .stop // if (r5<=0) goto .stop
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.start:
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movs r6, #0x80 // reset mask
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ldrb r0, [r4, #0] // r0 := *r4
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muls r0, r7
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lsrs r0, r0, #8 // r0 >>= 8
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str r1, [r3, #0xC] // pin := lo
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b .nextbit //
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.stop:
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str r1, [r3, #0xC] // pin := lo
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pop {r4,r5,r6,r7,pc}
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#endif
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