-
Notifications
You must be signed in to change notification settings - Fork 0
Expand file tree
/
Copy pathmult.asm
More file actions
91 lines (85 loc) · 1.81 KB
/
mult.asm
File metadata and controls
91 lines (85 loc) · 1.81 KB
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
; this routine runs with P=5, called from P=4
; [V_WORK_0]: result (higher, lower), x.xxxxx00 * ssyyyyyyyyyyyyyyy = smmmmmmmmmmmmmmm
; preserve PC_SUBSUB
R_MULTIPLICAND .eq $E ; integer; ssyyyyyyyyyyyyyyy
R_MULT_CNT .eq $F ; lower byte
R_MULTIPLIER .eq $F ; upper 6 bits of lower byte(unsigned fixed point x.xxxxx), last 2 bits ignored
; MULT_START to MULT_END: 105 to 147 instructions
.no $01B0
MULT_EXIT
SEP PC_SUB
MULT_ENTRY
LDI #V_WORK_0
PLO R_WORK_PTR
LDI $00
STR R_WORK_PTR
INC R_WORK_PTR
STR R_WORK_PTR
SEX R_WORK_PTR
LDI $06
MULT_A
PLO R_MULT_CNT
GHI R_MULTIPLIER
SHL
PHI R_MULTIPLIER
BNF MULT_B
GLO R_MULTIPLICAND
ADD
STXD
GHI R_MULTIPLICAND
ADC
STR R_WORK_PTR
INC R_WORK_PTR
MULT_B
GHI R_MULTIPLICAND
SHL
GHI R_MULTIPLICAND
SHRC
PHI R_MULTIPLICAND
GLO R_MULTIPLICAND
SHRC
PLO R_MULTIPLICAND
DEC R_MULT_CNT
GLO R_MULT_CNT
BNZ MULT_A
BR MULT_EXIT
; MULT_6_16
; R_WORK_PTR .eq $9 ; upper = $0D
; R_MULTIPLICAND .eq $E 16 bits, signed or unsigned
; R_MULT_CNT .eq $F lower byte
; R_MULTIPLIER .eq $F lower 6 bits of higher byte, unsigned
; [V_WORK_1]: result (higher, lower)
; destroy PC_SUBSUB
MULT_6_16_ENTRY
LDI #V_WORK_1
PLO R_WORK_PTR
LDI $00
STR R_WORK_PTR
INC R_WORK_PTR
STR R_WORK_PTR
SEX R_WORK_PTR
LDI $06
MULT_6_16_A
PLO R_MULT_CNT
GHI R_MULTIPLIER
SHR
PHI R_MULTIPLIER
BNF MULT_6_16_B
GLO R_MULTIPLICAND
ADD
STXD
GHI R_MULTIPLICAND
ADC
STR R_WORK_PTR
INC R_WORK_PTR
MULT_6_16_B
GLO R_MULTIPLICAND
SHL
PLO R_MULTIPLICAND
GHI R_MULTIPLICAND
SHLC
PHI R_MULTIPLICAND
DEC R_MULT_CNT
GLO R_MULT_CNT
BNZ MULT_6_16_A
SEP PC_SUB