SubGhz: faster mess_with_iv (#845)
* subghz_keystore_mess_with_iv shortened - less instructions - less registers used (no need for r3 anymore) * subghz_keystore_mess_with_iv shortened (again) * 7b46c12e408cdc541e9e91c0392365bb4960fabd reduced instructions count from 4+16x8=132 to 3+16x7=115 * here loop is removed and reduces all to only 15 instructions * branch label is kept to preserve original intent and for historical record
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@ -81,19 +81,22 @@ static void subghz_keystore_mess_with_iv(uint8_t* iv) {
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// Sharing them will bring some discomfort to legal owners
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// And potential legal action against you
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// While you reading this code think about your own personal responsibility
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asm volatile("movs r0, #0x0 \n"
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"movs r1, #0x0 \n"
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"movs r2, #0x0 \n"
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"movs r3, #0x0 \n"
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"nani: \n"
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"ldrb r1, [r0, %0]\n"
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"mov r2, r1 \n"
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"add r1, r3 \n"
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"mov r3, r2 \n"
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"strb r1, [r0, %0]\n"
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"adds r0, #0x1 \n"
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"cmp r0, #0xF \n"
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"bls nani \n"
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asm volatile("nani: \n"
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"ldrd r0, r2, [%0, #0x0] \n"
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"lsl r1, r0, #8 \n"
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"lsl r3, r2, #8 \n"
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"orr r3, r3, r0, lsr #24\n"
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"uadd8 r1, r1, r0 \n"
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"uadd8 r3, r3, r2 \n"
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"strd r1, r3, [%0, #0x0] \n"
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"ldrd r1, r3, [%0, #0x8] \n"
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"lsl r0, r1, #8 \n"
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"orr r0, r0, r2, lsr #24\n"
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"lsl r2, r3, #8 \n"
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"orr r2, r2, r1, lsr #24\n"
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"uadd8 r1, r1, r0 \n"
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"uadd8 r3, r3, r2 \n"
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"strd r1, r3, [%0, #0x8] \n"
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:
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: "r"(iv)
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: "r0", "r1", "r2", "r3", "memory");
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