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Implement NSAU

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The libgcc1 __umodsi3 implementation for xtensa-lx106 uses this as Count
Leading Zeros.
This commit is contained in:
Sebastian Schmidt
2020-01-05 12:27:19 +01:00
parent f0faee57e4
commit c21f1866e7
1 changed files with 15 additions and 1 deletions
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16
data/languages/xtensaInstructions.sinc
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@ -831,7 +831,21 @@ macro extract_bit(val, bit, result) {
# NSAU - Normalization Shift Amount Unsigned, pg. 462. (Count leading zeros)
:nsau at, as is op2 = 0b0100 & op1 = 0 & ar = 0b1111 & as & at & op0 = 0 {
at = nsau(as);
local z4 = as[16,16] == 0;
local t3 = zext(z4)*as[0,16] + zext(!z4)*as[16,16];
local z3 = t3[8,8] == 0;
local t2 = (z3)*t3[0,8] + (!z3)*t3[8,8];
local z2 = t2[4,4] == 0;
local t1 = (z2)*t2[0,4] + (!z2)*t2[4,4];
local z1 = t1[2,2] == 0;
local z0 = (z1)*(t1[1,1] == 0) + (!z1)*(t1[3,1] == 0);
local all0 = as == 0;
at = zext((all0)*32 + (!all0)*(z4<<4 | z3<<3 | z2<<2 | z1<<1 | z0));
}
# OEQ.S - Compare Single Equal, pg. 463.