76 lines
2.9 KiB
C
76 lines
2.9 KiB
C
/**
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* Copyright (c) 2020 Raspberry Pi (Trading) Ltd.
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*
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* SPDX-License-Identifier: BSD-3-Clause
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*/
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#include <stdio.h>
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#include "pico/stdlib.h"
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#include "hardware/divider.h"
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/// \tag::hello_divider[]
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int main() {
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stdio_init_all();
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printf("Hello, divider!\n");
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// This is the basic hardware divider function
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int32_t dividend = 123456;
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int32_t divisor = -321;
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divmod_result_t result = hw_divider_divmod_s32(dividend, divisor);
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printf("%d/%d = %d remainder %d\n", dividend, divisor, to_quotient_s32(result), to_remainder_s32(result));
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// Is it right?
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printf("Working backwards! Result %d should equal %d!\n\n",
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to_quotient_s32(result) * divisor + to_remainder_s32(result), dividend);
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// This is the recommended unsigned fast divider for general use.
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int32_t udividend = 123456;
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int32_t udivisor = 321;
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divmod_result_t uresult = hw_divider_divmod_u32(udividend, udivisor);
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printf("%d/%d = %d remainder %d\n", udividend, udivisor, to_quotient_u32(uresult), to_remainder_u32(uresult));
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// Is it right?
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printf("Working backwards! Result %d should equal %d!\n\n",
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to_quotient_u32(result) * divisor + to_remainder_u32(result), dividend);
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// You can also do divides asynchronously. Divides will be complete after 8 cyles.
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hw_divider_divmod_s32_start(dividend, divisor);
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// Do something for 8 cycles!
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// In this example, our results function will wait for completion.
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// Use hw_divider_result_nowait() if you don't want to wait, but are sure you have delayed at least 8 cycles
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result = hw_divider_result_wait();
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printf("Async result %d/%d = %d remainder %d\n", dividend, divisor, to_quotient_s32(result),
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to_remainder_s32(result));
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// For a really fast divide, you can use the inlined versions... the / involves a function call as / always does
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// when using the ARM AEABI, so if you really want the best performance use the inlined versions.
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// Note that the / operator function DOES use the hardware divider by default, although you can change
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// that behavior by calling pico_set_divider_implementation in the cmake build for your target.
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printf("%d / %d = (by operator %d) (inlined %d)\n", dividend, divisor,
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dividend / divisor, hw_divider_s32_quotient_inlined(dividend, divisor));
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// Note however you must manually save/restore the divider state if you call the inlined methods from within an IRQ
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// handler.
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hw_divider_state_t state;
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hw_divider_divmod_s32_start(dividend, divisor);
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hw_divider_save_state(&state);
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hw_divider_divmod_s32_start(123, 7);
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printf("inner %d / %d = %d\n", 123, 7, hw_divider_s32_quotient_wait());
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hw_divider_restore_state(&state);
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int32_t tmp = hw_divider_s32_quotient_wait();
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printf("outer divide %d / %d = %d\n", dividend, divisor, tmp);
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return 0;
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}
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/// \end::hello_divider[]
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