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https://github.com/GearsProgress/Poke_Transporter_GB.git
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750641c78f
To protect the world from the soft float library... To unite all arithmetic within our binary... To denounce the evils of floating point precision... To save more kilobytes - that's our vision.... (god this is cringe) All floating point math has been eliminated, and replaced with equivalent or near-equivalent fixed-point math. sprite_data.cpp uses Q16, and get_rand_range uses a full Q32 to ensure that the exact same results are generated as before, at the cost of some inline assembly to do a umull (__aeabi_lmul is a little excessive when the lower 32 bits are discarded) This eliminates all of the expensive double precision float library, saving a few kilobytes. Additionally, the unneccessary parts of nanoprintf have been disabled. There is no need for precision specifiers, long longs, or floats.
54 lines
1.0 KiB
C++
54 lines
1.0 KiB
C++
#include "random.h"
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#include <tonc.h>
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unsigned int u32_rand;
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void rand_set_seed(unsigned int init_seed)
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{
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u32_rand = init_seed;
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}
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unsigned int rand_get_seed()
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{
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return u32_rand;
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}
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void rand_next_frame()
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{
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u32_rand = (0x41C64E6D * u32_rand) + 0x6073; // This is the randomization method used in Gen 3
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}
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u32 get_rand_u32()
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{
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rand_next_frame();
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return u32_rand;
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}
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u16 get_rand_u16()
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{
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rand_next_frame();
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return (u32_rand >> 16);
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}
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u32 get_rev_rand_u32(u32 input)
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{
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return (input - 24691) * 4005161829;
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}
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u16 get_rev_rand_u16(u32 input)
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{
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return (get_rev_rand_u32(input) >> 16);
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}
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// Force ARM mode. In Thumb mode this imports __aeabi_lmul.
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__attribute__((target("arm"), noinline))
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static unsigned multiply_high(unsigned x, unsigned y)
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{
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return ((unsigned long long)x * y) >> 32; // umull
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}
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unsigned get_rand_range(unsigned inc_min, unsigned exc_max)
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{
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// fixed point: get_rand_u32() / (float)0x100000000 * (exc_max - inc_min) + inc_min
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return multiply_high(get_rand_u32(), exc_max - inc_min) + inc_min;
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} |