From: Paul Mackerras Date: Thu, 30 Jul 2020 06:11:58 +0000 (+1000) Subject: FPU: Implement frsqrte[s] and a test for frsqrte X-Git-Url: https://git.libre-soc.org/?a=commitdiff_plain;h=394f993e75abaf1d23eba046c8bec59664439b3d;p=microwatt.git FPU: Implement frsqrte[s] and a test for frsqrte This implements frsqrte by table lookup. We first normalize the input if necessary and adjust so that the exponent is even, giving us a mantissa value in the range [1.0, 4.0), which is then used to look up an entry in a 768-entry table. The 768 entries are appended to the table for reciprocal estimates, giving a table of 1024 entries in total. frsqrtes is implemented identically to frsqrte. The estimate supplied is accurate to 1 part in 1024 or better. Signed-off-by: Paul Mackerras --- diff --git a/decode1.vhdl b/decode1.vhdl index ba9964e..7163ff9 100644 --- a/decode1.vhdl +++ b/decode1.vhdl @@ -421,6 +421,7 @@ architecture behaviour of decode1 is 2#10101# => (FPU, OP_FPOP, FRA, FRB, NONE, FRT, '0', '0', '0', '0', ZERO, '0', NONE, '0', '0', '0', '0', '1', '0', RC, '0', '0'), -- fadds 2#11000# => (FPU, OP_FPOP, NONE, FRB, NONE, FRT, '0', '0', '0', '0', ZERO, '0', NONE, '0', '0', '0', '0', '1', '0', RC, '0', '0'), -- fres 2#11001# => (FPU, OP_FPOP, FRA, NONE, FRC, FRT, '0', '0', '0', '0', ZERO, '0', NONE, '0', '0', '0', '0', '1', '0', RC, '0', '0'), -- fmuls + 2#11010# => (FPU, OP_FPOP, NONE, FRB, NONE, FRT, '0', '0', '0', '0', ZERO, '0', NONE, '0', '0', '0', '0', '1', '0', RC, '0', '0'), -- frsqrtes others => illegal_inst ); @@ -479,6 +480,7 @@ architecture behaviour of decode1 is 2#0111# => (FPU, OP_FPOP, FRA, FRB, FRC, FRT, '0', '0', '0', '0', ZERO, '0', NONE, '0', '0', '0', '0', '0', '0', RC, '0', '0'), -- fsel 2#1000# => (FPU, OP_FPOP, NONE, FRB, NONE, FRT, '0', '0', '0', '0', ZERO, '0', NONE, '0', '0', '0', '0', '0', '0', RC, '0', '0'), -- fre 2#1001# => (FPU, OP_FPOP, FRA, NONE, FRC, FRT, '0', '0', '0', '0', ZERO, '0', NONE, '0', '0', '0', '0', '0', '0', RC, '0', '0'), -- fmul + 2#1010# => (FPU, OP_FPOP, NONE, FRB, NONE, FRT, '0', '0', '0', '0', ZERO, '0', NONE, '0', '0', '0', '0', '0', '0', RC, '0', '0'), -- frsqrte others => illegal_inst ); diff --git a/fpu.vhdl b/fpu.vhdl index c726be3..0cbd43f 100644 --- a/fpu.vhdl +++ b/fpu.vhdl @@ -41,7 +41,7 @@ architecture behaviour of fpu is DO_FCFID, DO_FCTI, DO_FRSP, DO_FRI, DO_FADD, DO_FMUL, DO_FDIV, - DO_FRE, + DO_FRE, DO_FRSQRTE, DO_FSEL, FRI_1, ADD_SHIFT, ADD_2, ADD_3, @@ -50,6 +50,7 @@ architecture behaviour of fpu is LOOKUP, DIV_2, DIV_3, DIV_4, DIV_5, DIV_6, FRE_1, + RSQRT_1, INT_SHIFT, INT_ROUND, INT_ISHIFT, INT_FINAL, INT_CHECK, INT_OFLOW, FINISH, NORMALIZE, @@ -98,11 +99,12 @@ architecture behaviour of fpu is exp_cmp : std_ulogic; add_bsmall : std_ulogic; is_multiply : std_ulogic; + is_sqrt : std_ulogic; first : std_ulogic; count : unsigned(1 downto 0); end record; - type lookup_table is array(0 to 255) of std_ulogic_vector(17 downto 0); + type lookup_table is array(0 to 1023) of std_ulogic_vector(17 downto 0); signal r, rin : reg_type; @@ -160,6 +162,8 @@ architecture behaviour of fpu is constant MULADD_A : std_ulogic_vector(1 downto 0) := "10"; -- Inverse lookup table, indexed by the top 8 fraction bits + -- The first 256 entries are the reciprocal (1/x) lookup table, + -- and the remaining 768 entries are the reciprocal square root table. -- Output range is [0.5, 1) in 0.19 format, though the top -- bit isn't stored since it is always 1. -- Each output value is the inverse of the center of the input @@ -199,7 +203,109 @@ architecture behaviour of fpu is 18x"04321", 18x"040dd", 18x"03e9b", 18x"03c5c", 18x"03a1f", 18x"037e4", 18x"035ac", 18x"03376", 18x"03142", 18x"02f11", 18x"02ce2", 18x"02ab5", 18x"0288b", 18x"02663", 18x"0243d", 18x"02219", 18x"01ff7", 18x"01dd8", 18x"01bbb", 18x"019a0", 18x"01787", 18x"01570", 18x"0135b", 18x"01149", - 18x"00f39", 18x"00d2a", 18x"00b1e", 18x"00914", 18x"0070c", 18x"00506", 18x"00302", 18x"00100" + 18x"00f39", 18x"00d2a", 18x"00b1e", 18x"00914", 18x"0070c", 18x"00506", 18x"00302", 18x"00100", + -- 1/sqrt(x) lookup table + -- Input is in the range [1, 4), i.e. two bits to the left of the + -- binary point. Those 2 bits index the following 3 blocks of 256 values. + -- 1.0 ... 1.9999 + 18x"3fe00", 18x"3fa06", 18x"3f612", 18x"3f224", 18x"3ee3a", 18x"3ea58", 18x"3e67c", 18x"3e2a4", + 18x"3ded2", 18x"3db06", 18x"3d73e", 18x"3d37e", 18x"3cfc2", 18x"3cc0a", 18x"3c85a", 18x"3c4ae", + 18x"3c106", 18x"3bd64", 18x"3b9c8", 18x"3b630", 18x"3b29e", 18x"3af10", 18x"3ab86", 18x"3a802", + 18x"3a484", 18x"3a108", 18x"39d94", 18x"39a22", 18x"396b6", 18x"3934e", 18x"38fea", 18x"38c8c", + 18x"38932", 18x"385dc", 18x"3828a", 18x"37f3e", 18x"37bf6", 18x"378b2", 18x"37572", 18x"37236", + 18x"36efe", 18x"36bca", 18x"3689a", 18x"36570", 18x"36248", 18x"35f26", 18x"35c06", 18x"358ea", + 18x"355d4", 18x"352c0", 18x"34fb0", 18x"34ca4", 18x"3499c", 18x"34698", 18x"34398", 18x"3409c", + 18x"33da2", 18x"33aac", 18x"337bc", 18x"334cc", 18x"331e2", 18x"32efc", 18x"32c18", 18x"32938", + 18x"3265a", 18x"32382", 18x"320ac", 18x"31dd8", 18x"31b0a", 18x"3183e", 18x"31576", 18x"312b0", + 18x"30fee", 18x"30d2e", 18x"30a74", 18x"307ba", 18x"30506", 18x"30254", 18x"2ffa4", 18x"2fcf8", + 18x"2fa4e", 18x"2f7a8", 18x"2f506", 18x"2f266", 18x"2efca", 18x"2ed2e", 18x"2ea98", 18x"2e804", + 18x"2e572", 18x"2e2e4", 18x"2e058", 18x"2ddce", 18x"2db48", 18x"2d8c6", 18x"2d646", 18x"2d3c8", + 18x"2d14c", 18x"2ced4", 18x"2cc5e", 18x"2c9ea", 18x"2c77a", 18x"2c50c", 18x"2c2a2", 18x"2c038", + 18x"2bdd2", 18x"2bb70", 18x"2b90e", 18x"2b6b0", 18x"2b454", 18x"2b1fa", 18x"2afa4", 18x"2ad4e", + 18x"2aafc", 18x"2a8ac", 18x"2a660", 18x"2a414", 18x"2a1cc", 18x"29f86", 18x"29d42", 18x"29b00", + 18x"298c2", 18x"29684", 18x"2944a", 18x"29210", 18x"28fda", 18x"28da6", 18x"28b74", 18x"28946", + 18x"28718", 18x"284ec", 18x"282c4", 18x"2809c", 18x"27e78", 18x"27c56", 18x"27a34", 18x"27816", + 18x"275fa", 18x"273e0", 18x"271c8", 18x"26fb0", 18x"26d9c", 18x"26b8a", 18x"2697a", 18x"2676c", + 18x"26560", 18x"26356", 18x"2614c", 18x"25f46", 18x"25d42", 18x"25b40", 18x"2593e", 18x"25740", + 18x"25542", 18x"25348", 18x"2514e", 18x"24f58", 18x"24d62", 18x"24b6e", 18x"2497c", 18x"2478c", + 18x"2459e", 18x"243b0", 18x"241c6", 18x"23fde", 18x"23df6", 18x"23c10", 18x"23a2c", 18x"2384a", + 18x"2366a", 18x"2348c", 18x"232ae", 18x"230d2", 18x"22efa", 18x"22d20", 18x"22b4a", 18x"22976", + 18x"227a2", 18x"225d2", 18x"22402", 18x"22234", 18x"22066", 18x"21e9c", 18x"21cd2", 18x"21b0a", + 18x"21944", 18x"2177e", 18x"215ba", 18x"213fa", 18x"21238", 18x"2107a", 18x"20ebc", 18x"20d00", + 18x"20b46", 18x"2098e", 18x"207d6", 18x"20620", 18x"2046c", 18x"202b8", 18x"20108", 18x"1ff58", + 18x"1fda8", 18x"1fbfc", 18x"1fa50", 18x"1f8a4", 18x"1f6fc", 18x"1f554", 18x"1f3ae", 18x"1f208", + 18x"1f064", 18x"1eec2", 18x"1ed22", 18x"1eb82", 18x"1e9e4", 18x"1e846", 18x"1e6aa", 18x"1e510", + 18x"1e378", 18x"1e1e0", 18x"1e04a", 18x"1deb4", 18x"1dd20", 18x"1db8e", 18x"1d9fc", 18x"1d86c", + 18x"1d6de", 18x"1d550", 18x"1d3c4", 18x"1d238", 18x"1d0ae", 18x"1cf26", 18x"1cd9e", 18x"1cc18", + 18x"1ca94", 18x"1c910", 18x"1c78c", 18x"1c60a", 18x"1c48a", 18x"1c30c", 18x"1c18e", 18x"1c010", + 18x"1be94", 18x"1bd1a", 18x"1bba0", 18x"1ba28", 18x"1b8b2", 18x"1b73c", 18x"1b5c6", 18x"1b452", + 18x"1b2e0", 18x"1b16e", 18x"1affe", 18x"1ae8e", 18x"1ad20", 18x"1abb4", 18x"1aa46", 18x"1a8dc", + -- 2.0 ... 2.9999 + 18x"1a772", 18x"1a608", 18x"1a4a0", 18x"1a33a", 18x"1a1d4", 18x"1a070", 18x"19f0c", 18x"19da8", + 18x"19c48", 18x"19ae6", 18x"19986", 18x"19828", 18x"196ca", 18x"1956e", 18x"19412", 18x"192b8", + 18x"1915e", 18x"19004", 18x"18eae", 18x"18d56", 18x"18c00", 18x"18aac", 18x"18958", 18x"18804", + 18x"186b2", 18x"18562", 18x"18412", 18x"182c2", 18x"18174", 18x"18026", 18x"17eda", 18x"17d8e", + 18x"17c44", 18x"17afa", 18x"179b2", 18x"1786a", 18x"17724", 18x"175de", 18x"17498", 18x"17354", + 18x"17210", 18x"170ce", 18x"16f8c", 18x"16e4c", 18x"16d0c", 18x"16bcc", 18x"16a8e", 18x"16950", + 18x"16814", 18x"166d8", 18x"1659e", 18x"16464", 18x"1632a", 18x"161f2", 18x"160ba", 18x"15f84", + 18x"15e4e", 18x"15d1a", 18x"15be6", 18x"15ab2", 18x"15980", 18x"1584e", 18x"1571c", 18x"155ec", + 18x"154bc", 18x"1538e", 18x"15260", 18x"15134", 18x"15006", 18x"14edc", 18x"14db0", 18x"14c86", + 18x"14b5e", 18x"14a36", 18x"1490e", 18x"147e6", 18x"146c0", 18x"1459a", 18x"14476", 18x"14352", + 18x"14230", 18x"1410c", 18x"13fea", 18x"13eca", 18x"13daa", 18x"13c8a", 18x"13b6c", 18x"13a4e", + 18x"13930", 18x"13814", 18x"136f8", 18x"135dc", 18x"134c2", 18x"133a8", 18x"1328e", 18x"13176", + 18x"1305e", 18x"12f48", 18x"12e30", 18x"12d1a", 18x"12c06", 18x"12af2", 18x"129de", 18x"128ca", + 18x"127b8", 18x"126a6", 18x"12596", 18x"12486", 18x"12376", 18x"12266", 18x"12158", 18x"1204a", + 18x"11f3e", 18x"11e32", 18x"11d26", 18x"11c1a", 18x"11b10", 18x"11a06", 18x"118fc", 18x"117f4", + 18x"116ec", 18x"115e4", 18x"114de", 18x"113d8", 18x"112d2", 18x"111ce", 18x"110ca", 18x"10fc6", + 18x"10ec2", 18x"10dc0", 18x"10cbe", 18x"10bbc", 18x"10abc", 18x"109bc", 18x"108bc", 18x"107be", + 18x"106c0", 18x"105c2", 18x"104c4", 18x"103c8", 18x"102cc", 18x"101d0", 18x"100d6", 18x"0ffdc", + 18x"0fee2", 18x"0fdea", 18x"0fcf0", 18x"0fbf8", 18x"0fb02", 18x"0fa0a", 18x"0f914", 18x"0f81e", + 18x"0f72a", 18x"0f636", 18x"0f542", 18x"0f44e", 18x"0f35a", 18x"0f268", 18x"0f176", 18x"0f086", + 18x"0ef94", 18x"0eea4", 18x"0edb4", 18x"0ecc6", 18x"0ebd6", 18x"0eae8", 18x"0e9fa", 18x"0e90e", + 18x"0e822", 18x"0e736", 18x"0e64a", 18x"0e55e", 18x"0e474", 18x"0e38a", 18x"0e2a0", 18x"0e1b8", + 18x"0e0d0", 18x"0dfe8", 18x"0df00", 18x"0de1a", 18x"0dd32", 18x"0dc4c", 18x"0db68", 18x"0da82", + 18x"0d99e", 18x"0d8ba", 18x"0d7d6", 18x"0d6f4", 18x"0d612", 18x"0d530", 18x"0d44e", 18x"0d36c", + 18x"0d28c", 18x"0d1ac", 18x"0d0cc", 18x"0cfee", 18x"0cf0e", 18x"0ce30", 18x"0cd54", 18x"0cc76", + 18x"0cb9a", 18x"0cabc", 18x"0c9e0", 18x"0c906", 18x"0c82a", 18x"0c750", 18x"0c676", 18x"0c59c", + 18x"0c4c4", 18x"0c3ea", 18x"0c312", 18x"0c23a", 18x"0c164", 18x"0c08c", 18x"0bfb6", 18x"0bee0", + 18x"0be0a", 18x"0bd36", 18x"0bc62", 18x"0bb8c", 18x"0baba", 18x"0b9e6", 18x"0b912", 18x"0b840", + 18x"0b76e", 18x"0b69c", 18x"0b5cc", 18x"0b4fa", 18x"0b42a", 18x"0b35a", 18x"0b28a", 18x"0b1bc", + 18x"0b0ee", 18x"0b01e", 18x"0af50", 18x"0ae84", 18x"0adb6", 18x"0acea", 18x"0ac1e", 18x"0ab52", + 18x"0aa86", 18x"0a9bc", 18x"0a8f0", 18x"0a826", 18x"0a75c", 18x"0a694", 18x"0a5ca", 18x"0a502", + 18x"0a43a", 18x"0a372", 18x"0a2aa", 18x"0a1e4", 18x"0a11c", 18x"0a056", 18x"09f90", 18x"09ecc", + -- 3.0 ... 3.9999 + 18x"09e06", 18x"09d42", 18x"09c7e", 18x"09bba", 18x"09af6", 18x"09a32", 18x"09970", 18x"098ae", + 18x"097ec", 18x"0972a", 18x"09668", 18x"095a8", 18x"094e8", 18x"09426", 18x"09368", 18x"092a8", + 18x"091e8", 18x"0912a", 18x"0906c", 18x"08fae", 18x"08ef0", 18x"08e32", 18x"08d76", 18x"08cba", + 18x"08bfe", 18x"08b42", 18x"08a86", 18x"089ca", 18x"08910", 18x"08856", 18x"0879c", 18x"086e2", + 18x"08628", 18x"08570", 18x"084b6", 18x"083fe", 18x"08346", 18x"0828e", 18x"081d8", 18x"08120", + 18x"0806a", 18x"07fb4", 18x"07efe", 18x"07e48", 18x"07d92", 18x"07cde", 18x"07c2a", 18x"07b76", + 18x"07ac2", 18x"07a0e", 18x"0795a", 18x"078a8", 18x"077f4", 18x"07742", 18x"07690", 18x"075de", + 18x"0752e", 18x"0747c", 18x"073cc", 18x"0731c", 18x"0726c", 18x"071bc", 18x"0710c", 18x"0705e", + 18x"06fae", 18x"06f00", 18x"06e52", 18x"06da4", 18x"06cf6", 18x"06c4a", 18x"06b9c", 18x"06af0", + 18x"06a44", 18x"06998", 18x"068ec", 18x"06840", 18x"06796", 18x"066ea", 18x"06640", 18x"06596", + 18x"064ec", 18x"06442", 18x"0639a", 18x"062f0", 18x"06248", 18x"061a0", 18x"060f8", 18x"06050", + 18x"05fa8", 18x"05f00", 18x"05e5a", 18x"05db4", 18x"05d0e", 18x"05c68", 18x"05bc2", 18x"05b1c", + 18x"05a76", 18x"059d2", 18x"0592e", 18x"05888", 18x"057e4", 18x"05742", 18x"0569e", 18x"055fa", + 18x"05558", 18x"054b6", 18x"05412", 18x"05370", 18x"052ce", 18x"0522e", 18x"0518c", 18x"050ec", + 18x"0504a", 18x"04faa", 18x"04f0a", 18x"04e6a", 18x"04dca", 18x"04d2c", 18x"04c8c", 18x"04bee", + 18x"04b50", 18x"04ab0", 18x"04a12", 18x"04976", 18x"048d8", 18x"0483a", 18x"0479e", 18x"04700", + 18x"04664", 18x"045c8", 18x"0452c", 18x"04490", 18x"043f6", 18x"0435a", 18x"042c0", 18x"04226", + 18x"0418a", 18x"040f0", 18x"04056", 18x"03fbe", 18x"03f24", 18x"03e8c", 18x"03df2", 18x"03d5a", + 18x"03cc2", 18x"03c2a", 18x"03b92", 18x"03afa", 18x"03a62", 18x"039cc", 18x"03934", 18x"0389e", + 18x"03808", 18x"03772", 18x"036dc", 18x"03646", 18x"035b2", 18x"0351c", 18x"03488", 18x"033f2", + 18x"0335e", 18x"032ca", 18x"03236", 18x"031a2", 18x"03110", 18x"0307c", 18x"02fea", 18x"02f56", + 18x"02ec4", 18x"02e32", 18x"02da0", 18x"02d0e", 18x"02c7c", 18x"02bec", 18x"02b5a", 18x"02aca", + 18x"02a38", 18x"029a8", 18x"02918", 18x"02888", 18x"027f8", 18x"0276a", 18x"026da", 18x"0264a", + 18x"025bc", 18x"0252e", 18x"024a0", 18x"02410", 18x"02384", 18x"022f6", 18x"02268", 18x"021da", + 18x"0214e", 18x"020c0", 18x"02034", 18x"01fa8", 18x"01f1c", 18x"01e90", 18x"01e04", 18x"01d78", + 18x"01cee", 18x"01c62", 18x"01bd8", 18x"01b4c", 18x"01ac2", 18x"01a38", 18x"019ae", 18x"01924", + 18x"0189c", 18x"01812", 18x"01788", 18x"01700", 18x"01676", 18x"015ee", 18x"01566", 18x"014de", + 18x"01456", 18x"013ce", 18x"01346", 18x"012c0", 18x"01238", 18x"011b2", 18x"0112c", 18x"010a4", + 18x"0101e", 18x"00f98", 18x"00f12", 18x"00e8c", 18x"00e08", 18x"00d82", 18x"00cfe", 18x"00c78", + 18x"00bf4", 18x"00b70", 18x"00aec", 18x"00a68", 18x"009e4", 18x"00960", 18x"008dc", 18x"00858", + 18x"007d6", 18x"00752", 18x"006d0", 18x"0064e", 18x"005cc", 18x"0054a", 18x"004c8", 18x"00446", + 18x"003c4", 18x"00342", 18x"002c2", 18x"00240", 18x"001c0", 18x"00140", 18x"000c0", 18x"00040" ); -- Left and right shifter with 120 bit input and 64 bit output. @@ -424,9 +530,17 @@ begin -- synchronous reads from lookup table lut_access: process(clk) + variable addrhi : std_ulogic_vector(1 downto 0); + variable addr : std_ulogic_vector(9 downto 0); begin if rising_edge(clk) then - inverse_est <= '1' & inverse_table(to_integer(unsigned(r.b.mantissa(53 downto 46)))); + if r.is_sqrt = '1' then + addrhi := r.b.mantissa(55 downto 54); + else + addrhi := "00"; + end if; + addr := addrhi & r.b.mantissa(53 downto 46); + inverse_est <= '1' & inverse_table(to_integer(unsigned(addr))); end if; end process; @@ -488,6 +602,8 @@ begin variable pcmpb_eq : std_ulogic; variable pcmpb_lt : std_ulogic; variable pshift : std_ulogic; + variable renorm_sqrt : std_ulogic; + variable sqrt_exp : signed(EXP_BITS-1 downto 0); begin v := r; illegal := '0'; @@ -519,6 +635,7 @@ begin v.round_mode := '0' & r.fpscr(FPSCR_RN+1 downto FPSCR_RN); v.is_subtract := '0'; v.is_multiply := '0'; + v.is_sqrt := '0'; v.add_bsmall := '0'; adec := decode_dp(e_in.fra, int_input); bdec := decode_dp(e_in.frb, int_input); @@ -599,6 +716,7 @@ begin msel_inv <= '0'; set_y := '0'; pshift := '0'; + renorm_sqrt := '0'; case r.state is when IDLE => if e_in.valid = '1' then @@ -654,6 +772,9 @@ begin when "11001" => v.is_multiply := '1'; v.state := DO_FMUL; + when "11010" => + v.is_sqrt := '1'; + v.state := DO_FRSQRTE; when others => illegal := '1'; end case; @@ -1157,6 +1278,48 @@ begin arith_done := '1'; end case; + when DO_FRSQRTE => + opsel_a <= AIN_B; + v.result_class := r.b.class; + v.result_sign := r.b.negative; + v.fpscr(FPSCR_FR) := '0'; + v.fpscr(FPSCR_FI) := '0'; + if r.b.class = NAN and r.b.mantissa(53) = '0' then + v.fpscr(FPSCR_VXSNAN) := '1'; + invalid := '1'; + end if; + v.shift := to_signed(1, EXP_BITS); + case r.b.class is + when FINITE => + v.result_exp := r.b.exponent; + if r.b.negative = '1' then + v.fpscr(FPSCR_VXSQRT) := '1'; + qnan_result := '1'; + arith_done := '1'; + elsif r.b.mantissa(54) = '0' then + v.state := RENORM_B; + elsif r.b.exponent(0) = '0' then + v.state := RSQRT_1; + else + v.state := RENORM_B2; + end if; + when NAN => + -- result is B + arith_done := '1'; + when INFINITY => + if r.b.negative = '1' then + v.fpscr(FPSCR_VXSQRT) := '1'; + qnan_result := '1'; + else + v.result_class := ZERO; + end if; + arith_done := '1'; + when ZERO => + v.result_class := INFINITY; + zero_divide := '1'; + arith_done := '1'; + end case; + when RENORM_A => renormalize := '1'; v.state := RENORM_A2; @@ -1184,11 +1347,16 @@ begin when RENORM_B => renormalize := '1'; + renorm_sqrt := r.is_sqrt; v.state := RENORM_B2; when RENORM_B2 => set_b := '1'; - v.result_exp := r.result_exp + r.shift; + if r.is_sqrt = '0' then + v.result_exp := r.result_exp + r.shift; + else + v.result_exp := new_exp; + end if; v.state := LOOKUP; when RENORM_C => @@ -1287,8 +1455,10 @@ begin v.first := '1'; if r.insn(4) = '0' then v.state := DIV_2; - else + elsif r.insn(2) = '0' then v.state := FRE_1; + else + v.state := RSQRT_1; end if; when DIV_2 => @@ -1367,6 +1537,14 @@ begin v.shift := to_signed(1, EXP_BITS); v.state := NORMALIZE; + when RSQRT_1 => + opsel_r <= RES_MISC; + misc_sel <= "0111"; + sqrt_exp := r.b.exponent(EXP_BITS-1) & r.b.exponent(EXP_BITS-1 downto 1); + v.result_exp := - sqrt_exp; + v.shift := to_signed(1, EXP_BITS); + v.state := NORMALIZE; + when INT_SHIFT => opsel_r <= RES_SHIFT; set_x := '1'; @@ -1807,6 +1985,10 @@ begin if renormalize = '1' then clz := count_left_zeroes(r.r); + if renorm_sqrt = '1' then + -- make denormalized value end up with even exponent + clz(0) := '1'; + end if; v.shift := resize(signed('0' & clz) - 9, EXP_BITS); end if; diff --git a/tests/fpu/fpu.c b/tests/fpu/fpu.c index 06da475..d9c5c06 100644 --- a/tests/fpu/fpu.c +++ b/tests/fpu/fpu.c @@ -1244,6 +1244,53 @@ int fpu_test_20(void) return trapit(0, test20); } +struct isqrtvals { + unsigned long val; + unsigned long inv; +} isqrtvals[] = { + { 0x0000000000000000, 0x7ff0000000000000 }, + { 0x8000000000000000, 0xfff0000000000000 }, + { 0xfff0000000000000, 0x7ff8000000000000 }, + { 0x7ff0000000000000, 0x0000000000000000 }, + { 0xfff123456789abcd, 0xfff923456789abcd }, + { 0x3ff0000000000000, 0x3feff80000000000 }, + { 0x4000000000000000, 0x3fe69dc800000000 }, + { 0x4010000000000000, 0x3fdff80000000000 }, + { 0xbff0000000000000, 0x7ff8000000000000 }, + { 0x4008000000000000, 0x3fe2781800000000 }, + { 0x7fd0000000000000, 0x1ffff80000000000 }, + { 0x0008000000000000, 0x5fe69dc800000000 }, + { 0x0004000000000000, 0x5feff80000000000 }, + { 0x0002000000000000, 0x5ff69dc800000000 }, + { 0x0000000000000002, 0x61769dc800000000 }, + { 0x0000000000000001, 0x617ff80000000000 }, +}; + +int test21(long arg) +{ + long i; + unsigned long result; + struct isqrtvals *vp = isqrtvals; + + set_fpscr(FPS_RN_NEAR); + for (i = 0; i < sizeof(isqrtvals) / sizeof(isqrtvals[0]); ++i, ++vp) { + asm("lfd 6,0(%0); frsqrte 7,6; stfd 7,0(%1)" + : : "b" (&vp->val), "b" (&result) : "memory"); + if (result != vp->inv) { + print_hex(i, 2, " "); + print_hex(result, 16, " "); + return i + 1; + } + } + return 0; +} + +int fpu_test_21(void) +{ + enable_fp(); + return trapit(0, test21); +} + int fail = 0; void do_test(int num, int (*test)(void)) @@ -1289,6 +1336,7 @@ int main(void) do_test(18, fpu_test_18); do_test(19, fpu_test_19); do_test(20, fpu_test_20); + do_test(21, fpu_test_21); return fail; } diff --git a/tests/test_fpu.bin b/tests/test_fpu.bin index 0f9e03a..0253720 100755 Binary files a/tests/test_fpu.bin and b/tests/test_fpu.bin differ diff --git a/tests/test_fpu.console_out b/tests/test_fpu.console_out index aea206f..b6bc733 100644 --- a/tests/test_fpu.console_out +++ b/tests/test_fpu.console_out @@ -18,3 +18,4 @@ test 17:PASS test 18:PASS test 19:PASS test 20:PASS +test 21:PASS