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