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collapseos
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zasm: add poor man's indexing in instr table 

There's a lot of looping through that table. At first, I wanted to add some
bisecting, but 16-bit additions and multiplications involved made the idea a
bit less appealing. I went with a very basic, hardcoded index which should
speed things quite a bit at a minimal complexity cost.
This commit is contained in:
Virgil Dupras 2019-11-11 20:59:26 -05:00
parent cbc6fb5931
commit 518df7a05e
1 changed files with 20 additions and 4 deletions
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24
apps/zasm/instr.asm
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@ -1,8 +1,6 @@
; *** Consts ***
; Number of rows in the argspec table
.equ ARGSPEC_TBL_CNT 33
; Number of rows in the primary instructions table
.equ INSTR_TBL_CNT 147
; size in bytes of each row in the primary instructions table
.equ INSTR_TBL_ROWSIZE 6
; Instruction IDs They correspond to the index of the table in instrNames
@ -873,15 +871,28 @@ parseInstruction:
jr nz, .error ; A is set to error
.nomorearg:
; Parsing done, no error, let's move forward to instr row matching!
; To speed up things a little, we use a poor man's indexing. Full
; bisecting would involve too much complexity.
ld a, c ; recall A param
ld de, instrTBl
ld b, INSTR_TBL_CNT
cp I_EX
jr c, .loop
ld de, instrTBlEX
cp I_LD
jr c, .loop
ld de, instrTBlLD
cp I_RET
jr c, .loop
ld de, instrTBlRET
.loop:
ld a, c ; recall A param
call matchPrimaryRow
jr z, .match
ld a, INSTR_TBL_ROWSIZE
call addDE
djnz .loop
ld a, (de)
cp 0xff
jr nz, .loop
; No signature match
ld a, ERR_BAD_ARG
jr .error
@ -1066,6 +1077,7 @@ instrNames:
; custom code.
; Bit 4: When in an 'l' argspec, this means "I accept IX and IY variants".
; This table needs to be kept in ascending order of I_* value.
instrTBl:
.db I_ADC, 'A', 'l', 0, 0x8e , 0 ; ADC A, (HL)
.db I_ADC, 'A', 0xb, 0, 0b10001000 , 0 ; ADC A, r
@ -1102,6 +1114,7 @@ instrTBl:
.db I_DI, 0, 0, 0, 0xf3 , 0 ; DI
.db I_DJNZ,'n', 0, 0x80, 0x10 , 0 ; DJNZ e
.db I_EI, 0, 0, 0, 0xfb , 0 ; EI
instrTBlEX:
.db I_EX, 'p', 'h', 0, 0xe3 , 0 ; EX (SP), HL
.db I_EX, 'p', 'X', 0, 0xdd, 0xe3 ; EX (SP), IX
.db I_EX, 'p', 'Y', 0, 0xfd, 0xe3 ; EX (SP), IY
@ -1131,6 +1144,7 @@ instrTBl:
.db I_JR, '=', 'n', 0x80, 0x30 , 0 ; JR NC, e
.db I_JR, 'Z', 'n', 0x80, 0x28 , 0 ; JR Z, e
.db I_JR, 'z', 'n', 0x80, 0x20 , 0 ; JR NZ, e
instrTBlLD:
.db I_LD, 'c', 'A', 0, 0x02 , 0 ; LD (BC), A
.db I_LD, 'e', 'A', 0, 0x12 , 0 ; LD (DE), A
.db I_LD, 'A', 'c', 0, 0x0a , 0 ; LD A, (BC)
@ -1185,6 +1199,7 @@ instrTBl:
.db I_PUSH,0x1, 0, 4, 0b11000101 , 0 ; PUSH qq
.db I_RES, 0xc, 'l', 0x53, 0xcb, 0b10000110 ; RES b, (HL) + (IX/Y)
.db I_RES, 0xc, 0xb, 0x20 \ .dw handleRESR ; RES b, r
instrTBlRET:
.db I_RET, 0, 0, 0, 0xc9 , 0 ; RET
.db I_RET, 0xa, 0, 3, 0b11000000 , 0 ; RET cc
.db I_RETI,0, 0, 0, 0xed, 0x4d ; RETI
@ -1214,3 +1229,4 @@ instrTBl:
.db I_XOR, 'l', 0, 0, 0xae , 0 ; XOR (HL)
.db I_XOR, 0xb, 0, 0, 0b10101000 , 0 ; XOR r
.db I_XOR, 'n', 0, 0, 0xee , 0 ; XOR n
.db 0xff