# vcg_shift --- generate a variety of shift-related code sequences
# mul_a_by --- generate code to multiply A_REG by a constant, quickly
ipointer function mul_a_by (constant)
integer constant
ipointer gen_shift, gen_generic, seq, gen_mr, lshift_a_by
integer ad (ADDR_DESC_SIZE)
select (constant)
when (-1)
return (gen_generic (TCA_INS))
when (0)
return (gen_generic (CRA_INS))
when (1)
return (0)
when (2)
return (lshift_a_by (1))
when (4)
return (lshift_a_by (2))
when (8)
return (lshift_a_by (3))
when (16)
return (lshift_a_by (4))
when (32)
return (lshift_a_by (5))
when (64)
return (lshift_a_by (6))
when (128)
return (lshift_a_by (7))
when (256)
return (lshift_a_by (8))
when (512)
return (lshift_a_by (9))
when (1024)
return (lshift_a_by (10))
when (2048)
return (lshift_a_by (11))
when (4096)
return (lshift_a_by (12))
when (8192)
return (lshift_a_by (13))
when (16384)
return (lshift_a_by (14))
else {
if (constant == :100000)
return (lshift_a_by (15))
else {
AD_MODE (ad) = ILIT_AM
AD_LIT1 (ad) = constant
return (seq (gen_mr (MPY_INS, ad), gen_generic (XCB_INS)))
}
}
end
# mul_l_by --- generate code to multiply L_REG by a constant, quickly
ipointer function mul_l_by (amount)
long_int amount
ipointer lshift_l_by, gen_generic, seq, gen_mr
integer ad (ADDR_DESC_SIZE), power
long_int kluge
equivalence (kluge, AD_LIT1 (ad))
# long_int powers_of_two (32)
# data powers_of_two / _
# 0000001, 0000002, 0000004, 0000008, 0000016, 0000032, 0000064,
# 0000128, 0000256, 0000512, 0001024, 0002048, 0004096, 0008192,
# 0016384, 0032768, 0065536, 131072, 262144, 524288,
# 1048576, 2097152, 4194304, 8388608, 16777216, 33554432,
# 67108864, 134217728, 268435456, 536870912, 1073741824,
# :20000000000/
include POWER_COM
for (power = 0; power <= 31; power += 1)
if (amount == powers_of_two (power + 1))
return (lshift_l_by (power))
if (amount == -1)
return (gen_generic (TCL_INS))
else if (amount == 0)
return (gen_generic (CRL_INS))
else {
AD_MODE (ad) = LLIT_AM
kluge = amount
return (seq (gen_mr (MPL_INS, ad), gen_generic (ILE_INS)))
}
end
# div_a_by --- generate code to divide A_REG by a constant, quickly
ipointer function div_a_by (amount, mode)
integer amount
integer mode # INT or UNS
ipointer rshift_a_by, seq, gen_generic, gen_mr
integer ad (ADDR_DESC_SIZE)
select (amount)
when (-1)
return (gen_generic (TCA_INS))
when (0) {
call warning ("divide by zero in input*n"p)
return (0)
}
when (1)
return (0)
if (mode == UNS_MODE) # we can try for a logical right shift
select (amount)
when (2)
return (rshift_a_by (1))
when (4)
return (rshift_a_by (2))
when (8)
return (rshift_a_by (3))
when (16)
return (rshift_a_by (4))
when (32 )
return (rshift_a_by (5))
when (64)
return (rshift_a_by (6))
when (128)
return (rshift_a_by (7))
when (256)
return (rshift_a_by (8))
when (512)
return (rshift_a_by (9))
when (1024)
return (rshift_a_by (10))
when (2048)
return (rshift_a_by (11))
when (4096)
return (rshift_a_by (12))
when (8192)
return (rshift_a_by (13))
when (16384)
return (rshift_a_by (14))
when (-32768)
return (rshift_a_by (15))
# Sigh. Have to generate a division operation.
AD_MODE (ad) = ILIT_AM
AD_LIT1 (ad) = amount
if (mode == INT_MODE)
return (seq (gen_generic (PIDA_INS), gen_mr (DIV_INS, ad)))
else
return (seq (gen_generic (XCA_INS), gen_mr (DIV_INS, ad)))
end
# div_l_by --- generate code to divide L_REG by a constant, quickly
ipointer function div_l_by (amount, mode)
long_int amount
integer mode # INT_MODE or UNS_MODE
ipointer rshift_l_by, gen_generic, seq, gen_mr
integer ad (ADDR_DESC_SIZE), power
long_int kluge
equivalence (kluge, AD_LIT1 (ad))
# long_int powers_of_two (32)
# data powers_of_two / _
# 0000001, 0000002, 0000004, 0000008, 0000016, 0000032, 0000064,
# 0000128, 0000256, 0000512, 0001024, 0002048, 0004096, 0008192,
# 0016384, 0032768, 0065536, 131072, 262144, 524288,
# 1048576, 2097152, 4194304, 8388608, 16777216, 33554432,
# 67108864, 134217728, 268435456, 536870912, 1073741824,
# :20000000000/
include POWER_COM
if (mode == UNS_MODE) # we can logical right shift for powers of 2
for (power = 0; power <= 31; power += 1)
if (amount == powers_of_two (power + 1))
return (rshift_l_by (power))
if (amount == -1)
return (gen_generic (TCL_INS))
else if (amount == 0) {
call warning ("divide by zero in input*n"p)
return (0)
}
else if (amount == 1)
return (0)
else {
AD_MODE (ad) = LLIT_AM
kluge = amount
if (mode == INT_MODE)
return (seq (gen_generic (PIDL_INS), gen_mr (DVL_INS, ad)))
return (seq (gen_generic (ILE_INS), gen_generic (CRL_INS),
gen_mr (DVL_INS, ad)))
}
end
# lshift_a_by --- generate code to shift A_REG left, quickly
ipointer function lshift_a_by (amount)
integer amount
include VCG_COMMON
ipointer gen_shift, gen_generic, seq
if (amount > 15)
return (gen_generic (CRA_INS))
if (amount < 0) {
call warning ("lshift_a_by: shift count < 0*n"p)
return (0)
}
select (amount)
when (0)
return (0)
when (1, 2, 3, 4, 5, 6, 7)
return (gen_shift (ALL_INS, amount))
when (8)
return (gen_generic (ICR_INS))
when (9, 10, 11, 12, 13, 14, 15)
return (seq (gen_generic (ICR_INS),
gen_shift (ALL_INS, amount - 8)))
else
call panic ("lshift_a_by: shift count > 15*n"p)
end
# lshift_l_by --- generate code to shift L_REG left, quickly
ipointer function lshift_l_by (amount)
integer amount
include VCG_COMMON
ipointer gen_shift, gen_generic, seq
if (amount > 31)
return (gen_generic (CRL_INS))
if (amount < 0) {
call warning ("lshift_l_by: shift count < 0*n"p)
return (0)
}
select (amount)
when (0)
return (0)
when (1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15)
return (gen_shift (LLL_INS, amount))
when (16)
return (gen_generic (XCB_INS))
when (17, 18, 19, 20, 21, 22, 23)
return (seq (gen_generic (XCB_INS),
gen_shift (ALL_INS, amount - 16)))
when (24)
return (seq (gen_generic (XCB_INS), gen_generic (ICR_INS)))
when (25, 26, 27, 28, 29, 30, 31)
return (seq (gen_generic (XCB_INS), gen_generic (ICR_INS),
gen_shift (ALL_INS, amount - 24)))
else
call panic ("lshift_l_by: shift count > 31*n"p)
end
# rshift_a_by --- generate code to shift A_REG right, quickly
ipointer function rshift_a_by (amount)
integer amount
include VCG_COMMON
ipointer gen_shift, gen_generic, seq
if (amount > 15)
return (gen_generic (CRA_INS))
if (amount < 0) {
call warning ("rshift_a_by: shift count < 0*n"p)
return (0)
}
select (amount)
when (0)
return (0)
when (1, 2, 3, 4, 5, 6, 7)
return (gen_shift (ARL_INS, amount))
when (8)
return (gen_generic (ICL_INS))
when (9, 10, 11, 12, 13, 14, 15)
return (seq (gen_generic (ICL_INS),
gen_shift (ARL_INS, amount - 8)))
else
call panic ("rshift_a_by: shift count > 15*n"p)
end
# rshift_l_by --- generate code to shift A_REG right, quickly
ipointer function rshift_l_by (amount)
integer amount
include VCG_COMMON
ipointer gen_shift, gen_generic, seq
if (amount > 31)
return (gen_generic (CRL_INS))
if (amount < 0) {
call warning ("rshift_l_by: shift count < 0*n"p)
return (0)
}
select (amount)
when (0)
return (0)
when (1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15)
return (gen_shift (LRL_INS, amount))
when (16)
return (gen_generic (XCA_INS))
when (17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31)
return (seq (gen_generic (XCA_INS),
gen_shift (LRL_INS, amount - 16)))
else
call panic ("rshift_l_by: shift count > 31*n"p)
end
# arshift_a_by --- arithmetic right shift A_REG, quickly
ipointer function arshift_a_by (amount)
integer amount
ipointer gen_shift
if (amount < 0 || amount > 16) {
call warning ("arshift_a_by: shift count out of range*n"p)
return (0)
}
if (amount == 0)
return (0)
return (gen_shift (ARS_INS, amount))
end
# arshift_l_by --- arithmetic right shift L_REG, quickly
ipointer function arshift_l_by (amount)
integer amount
ipointer gen_shift
if (amount < 0 || amount > 32) {
call warning ("arshift_l_by: shift count out of range*n"p)
return (0)
}
if (amount == 0)
return (0)
return (gen_shift (LRS_INS, amount))
end