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1.1 root 1: ;---------------------------Module-Header------------------------------;
2: ; Module Name: unroll.inc
3: ;
4: ; Equates and macros for loop unrolling.
5: ;
6: ; Copyright (c) 1992 Microsoft Corporation
7: ;-----------------------------------------------------------------------;
8:
9: ; Module including this must define LOOP_UNROLL_SHIFT. the log2 of the number
10: ; of times you want loops in this module unrolled. For example,
11: ; LOOP_UNROLL_SHIFT of 3 yields 2**3 = 8 times unrolling. This is the only
12: ; thing you need to change to control unrolling.
13:
14: ; # of times to unroll the loop, calculated as 2**n, where n is the
15: ; user-specified log2 of # of times to unroll the loop.
16:
17: LOOP_UNROLL_COUNT equ (1 shl LOOP_UNROLL_SHIFT)
18:
19: ;-----------------------------------------------------------------------;
20: ; Macro to generate an unrolled loop of UNROLL_COUNT instances of BASE_MACRO,
21: ; passing the base macro the info needed to construct a label of the form
22: ; BASE_LABELxxx, where xxx is UNROLL_COUNT the first time, and counts down by
23: ; one each time thereafter.
24:
25: UNROLL_LOOP macro BASE_MACRO,BASE_LABEL,UNROLL_COUNT
26:
27: INDEX=UNROLL_COUNT
28: rept UNROLL_COUNT ;-------------------------;
29: &BASE_MACRO &BASE_LABEL,%INDEX
30: INDEX=INDEX-1
31: endm ;-----------------------------------;
32:
33: endm ;-----------------------------------;
34:
35: ;-----------------------------------------------------------------------;
36: ; Macro to generate a dword memory variable that points to the label
37: ; specified by concatenating the label and the index.
38:
39: DEFINE_DD macro BASE_LABEL,INDEX ;------------------;
40: dd &BASE_LABEL&INDEX
41: endm ;-----------------------------------;
42:
43: ;-----------------------------------------------------------------------;
44: ; Macro to generate a table of vectors into an unrolled loop, for entering
45: ; to handle all possible fractional loops.
46:
47: UNROLL_LOOP_ENTRY_TABLE macro TABLE,BASE_LABEL,UNROLL_COUNT
48: align 4
49: TABLE label dword
50: DEFINE_DD BASE_LABEL,%&UNROLL_COUNT
51:
52: INDEX=1
53: rept UNROLL_COUNT-1
54: DEFINE_DD BASE_LABEL,%INDEX
55: INDEX=INDEX+1
56: endm ;-----------------------------------;
57:
58: endm ;-----------------------------------;
59:
60: ;-----------------------------------------------------------------------;
61: ; Given a loop count, a vector table, and unrolling parameters, this generates
62: ; COUNT_DEST = # of times to execute unrolled loop, VEC_DEST = entry point into
63: ; unrolled loop to perform whatever fractional loop is needed. Assumes dests
64: ; are registers.
65:
66: SET_UP_UNROLL_VARS macro COUNT_DEST,VEC_DEST,COUNT_SOURCE,VEC_TABLE,UNROLL_SHIFT
67: mov &VEC_DEST&,&COUNT_SOURCE& ;copy count to vector dest to
68: ; work with it
69: ifdifi <&COUNT_SOURCE&>,<&COUNT_DEST&>
70: mov &COUNT_DEST&,&COUNT_SOURCE& ;copy to count dest too, if not
71: endif ; same as count source
72: add &COUNT_DEST&,(1 shl LOOP_UNROLL_SHIFT)-1 ;round count up
73: and &VEC_DEST&,(1 shl LOOP_UNROLL_SHIFT)-1
74: ;fractional part of unrolled loop
75: shr &COUNT_DEST&,UNROLL_SHIFT ;# of repetitions of unrolled loop
76: mov &VEC_DEST&,&VEC_TABLE&[&VEC_DEST&*4]
77: ;place to jump into the unrolled
78: ; loop so as to handle the
79: ; fractional part first
80: endm ;-----------------------------------;
81:
82: ;-----------------------------------------------------------------------;
83: ; Given a loop count, a vector table, and unrolling parameters, this generates
84: ; COUNT_DEST = # of times to execute unrolled loop, VEC_DEST = entry point into
85: ; unrolled loop to perform whatever fractional loop is needed. Assumes dests
86: ; are registers.
87:
88: SET_UP_UNROLL_AND_BRANCH macro COUNT_REG,VEC_REG,VEC_TABLE,UNROLL_SHIFT
89: mov &VEC_REG&,&COUNT_REG& ;copy count to vector dest to
90: ; work with it
91: add &COUNT_reg&,(1 shl LOOP_UNROLL_SHIFT)-1 ;round count up
92: and &VEC_REG&,(1 shl LOOP_UNROLL_SHIFT)-1
93: ;fractional part of unrolled loop
94: shr &COUNT_REG&,UNROLL_SHIFT ;# of repetitions of unrolled loop
95: jmp dword ptr &VEC_TABLE&[&VEC_REG&*4]
96: ;jump into the unrolled loop so as
97: ; to handle the fractional part
98: ; first
99: endm ;-----------------------------------;
100:
101: ;-----------------------------------------------------------------------;
102:
103:
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