en:pfw:marsaglia_s_xorshift_for_arm
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| en:pfw:marsaglia_s_xorshift_for_arm [2024-10-08 23:01] – [Comparison of Forth vs assembly] jeroenh | en:pfw:marsaglia_s_xorshift_for_arm [2024-10-08 23:03] (current) – [Raspberry Pi 3b+ with wabiForth] jeroenh | ||
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| The Forth version of the randomisation routines is the same on any processor as only standard Forth words are used. But the ARM-processor can do do a neat | The Forth version of the randomisation routines is the same on any processor as only standard Forth words are used. But the ARM-processor can do do a neat | ||
| - | trick: it can do q cycle (dup, shift and xor) in 1 opcode!! And as | + | trick: it can do 1 cycle (dup, shift and xor) in 1 opcode!! And as |
| most Forths include an assembler it is an interesting exercise to see how | most Forths include an assembler it is an interesting exercise to see how | ||
| much faster the routine is when coded in assembly. | much faster the routine is when coded in assembly. | ||
| This example is coded using wabiForth on a Raspberry 3b+, but the principle is the same for any ARMv8 Aarch32 processor. | This example is coded using wabiForth on a Raspberry 3b+, but the principle is the same for any ARMv8 Aarch32 processor. | ||
| - | The routine uses two registers named top and w. Top contains the top of the stack, w is a scratch | + | The routine uses three registers named top, v and w. Top contains the top of the stack, |
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| random number on the stack with a given method. The routine in assembly | random number on the stack with a given method. The routine in assembly | ||
| is 3 times as fast as the corresponding routine in Forth. Which is a | is 3 times as fast as the corresponding routine in Forth. Which is a | ||
| - | nice speed-up of the routine. | + | decent |
en/pfw/marsaglia_s_xorshift_for_arm.1728421283.txt.gz · Last modified: 2024-10-08 23:01 by jeroenh