2 ; jidctint.asm - accurate integer IDCT (64-bit AVX2)
4 ; Copyright 2009 Pierre Ossman <ossman@cendio.se> for Cendio AB
5 ; Copyright (C) 2009, 2016, 2018, D. R. Commander.
7 ; Based on the x86 SIMD extension for IJG JPEG library
8 ; Copyright (C) 1999-2006, MIYASAKA Masaru.
9 ; For conditions of distribution and use, see copyright notice in jsimdext.inc
11 ; This file should be assembled with NASM (Netwide Assembler),
12 ; can *not* be assembled with Microsoft's MASM or any compatible
13 ; assembler (including Borland's Turbo Assembler).
14 ; NASM is available from http://nasm.sourceforge.net/ or
15 ; http://sourceforge.net/project/showfiles.php?group_id=6208
17 ; This file contains a slow-but-accurate integer implementation of the
18 ; inverse DCT (Discrete Cosine Transform). The following code is based
19 ; directly on the IJG's original jidctint.c; see the jidctint.c for
24 %include "jsimdext.inc"
27 ; --------------------------------------------------------------------------
32 %define DESCALE_P1 (CONST_BITS - PASS1_BITS)
33 %define DESCALE_P2 (CONST_BITS + PASS1_BITS + 3)
36 F_0_298 equ 2446 ; FIX(0.298631336)
37 F_0_390 equ 3196 ; FIX(0.390180644)
38 F_0_541 equ 4433 ; FIX(0.541196100)
39 F_0_765 equ 6270 ; FIX(0.765366865)
40 F_0_899 equ 7373 ; FIX(0.899976223)
41 F_1_175 equ 9633 ; FIX(1.175875602)
42 F_1_501 equ 12299 ; FIX(1.501321110)
43 F_1_847 equ 15137 ; FIX(1.847759065)
44 F_1_961 equ 16069 ; FIX(1.961570560)
45 F_2_053 equ 16819 ; FIX(2.053119869)
46 F_2_562 equ 20995 ; FIX(2.562915447)
47 F_3_072 equ 25172 ; FIX(3.072711026)
49 ; NASM cannot do compile-time arithmetic on floating-point constants.
50 %define DESCALE(x, n) (((x) + (1 << ((n) - 1))) >> (n))
51 F_0_298 equ DESCALE( 320652955, 30 - CONST_BITS) ; FIX(0.298631336)
52 F_0_390 equ DESCALE( 418953276, 30 - CONST_BITS) ; FIX(0.390180644)
53 F_0_541 equ DESCALE( 581104887, 30 - CONST_BITS) ; FIX(0.541196100)
54 F_0_765 equ DESCALE( 821806413, 30 - CONST_BITS) ; FIX(0.765366865)
55 F_0_899 equ DESCALE( 966342111, 30 - CONST_BITS) ; FIX(0.899976223)
56 F_1_175 equ DESCALE(1262586813, 30 - CONST_BITS) ; FIX(1.175875602)
57 F_1_501 equ DESCALE(1612031267, 30 - CONST_BITS) ; FIX(1.501321110)
58 F_1_847 equ DESCALE(1984016188, 30 - CONST_BITS) ; FIX(1.847759065)
59 F_1_961 equ DESCALE(2106220350, 30 - CONST_BITS) ; FIX(1.961570560)
60 F_2_053 equ DESCALE(2204520673, 30 - CONST_BITS) ; FIX(2.053119869)
61 F_2_562 equ DESCALE(2751909506, 30 - CONST_BITS) ; FIX(2.562915447)
62 F_3_072 equ DESCALE(3299298341, 30 - CONST_BITS) ; FIX(3.072711026)
65 ; --------------------------------------------------------------------------
66 ; In-place 8x8x16-bit inverse matrix transpose using AVX2 instructions
67 ; %1-%4: Input/output registers
68 ; %5-%8: Temp registers
71 ; %5=(00 10 20 30 40 50 60 70 01 11 21 31 41 51 61 71)
72 ; %6=(03 13 23 33 43 53 63 73 02 12 22 32 42 52 62 72)
73 ; %7=(04 14 24 34 44 54 64 74 05 15 25 35 45 55 65 75)
74 ; %8=(07 17 27 37 47 57 67 77 06 16 26 36 46 56 66 76)
80 ; transpose coefficients(phase 1)
81 ; %5=(00 10 20 30 01 11 21 31 40 50 60 70 41 51 61 71)
82 ; %6=(02 12 22 32 03 13 23 33 42 52 62 72 43 53 63 73)
83 ; %7=(04 14 24 34 05 15 25 35 44 54 64 74 45 55 65 75)
84 ; %8=(06 16 26 36 07 17 27 37 46 56 66 76 47 57 67 77)
90 ; transpose coefficients(phase 2)
91 ; %1=(00 02 10 12 20 22 30 32 40 42 50 52 60 62 70 72)
92 ; %2=(01 03 11 13 21 23 31 33 41 43 51 53 61 63 71 73)
93 ; %3=(04 06 14 16 24 26 34 36 44 46 54 56 64 66 74 76)
94 ; %4=(05 07 15 17 25 27 35 37 45 47 55 57 65 67 75 77)
100 ; transpose coefficients(phase 3)
101 ; %5=(00 01 02 03 10 11 12 13 40 41 42 43 50 51 52 53)
102 ; %6=(04 05 06 07 14 15 16 17 44 45 46 47 54 55 56 57)
103 ; %7=(20 21 22 23 30 31 32 33 60 61 62 63 70 71 72 73)
104 ; %8=(24 25 26 27 34 35 36 37 64 65 66 67 74 75 76 77)
106 vpunpcklqdq %1, %5, %6
107 vpunpckhqdq %2, %5, %6
108 vpunpcklqdq %3, %7, %8
109 vpunpckhqdq %4, %7, %8
110 ; transpose coefficients(phase 4)
111 ; %1=(00 01 02 03 04 05 06 07 40 41 42 43 44 45 46 47)
112 ; %2=(10 11 12 13 14 15 16 17 50 51 52 53 54 55 56 57)
113 ; %3=(20 21 22 23 24 25 26 27 60 61 62 63 64 65 66 67)
114 ; %4=(30 31 32 33 34 35 36 37 70 71 72 73 74 75 76 77)
117 ; --------------------------------------------------------------------------
118 ; In-place 8x8x16-bit slow integer inverse DCT using AVX2 instructions
119 ; %1-%4: Input/output registers
120 ; %5-%12: Temp registers
127 ; z1 = (z2 + z3) * 0.541196100;
128 ; tmp2 = z1 + z3 * -1.847759065;
129 ; tmp3 = z1 + z2 * 0.765366865;
131 ; (This implementation)
132 ; tmp2 = z2 * 0.541196100 + z3 * (0.541196100 - 1.847759065);
133 ; tmp3 = z2 * (0.541196100 + 0.765366865) + z3 * 0.541196100;
135 vperm2i128 %6, %3, %3, 0x01 ; %6=in6_2
136 vpunpcklwd %5, %3, %6 ; %5=in26_62L
137 vpunpckhwd %6, %3, %6 ; %6=in26_62H
138 vpmaddwd %5, %5, [rel PW_F130_F054_MF130_F054] ; %5=tmp3_2L
139 vpmaddwd %6, %6, [rel PW_F130_F054_MF130_F054] ; %6=tmp3_2H
141 vperm2i128 %7, %1, %1, 0x01 ; %7=in4_0
142 vpsignw %1, %1, [rel PW_1_NEG1]
143 vpaddw %7, %7, %1 ; %7=(in0+in4)_(in0-in4)
146 vpunpcklwd %8, %1, %7 ; %8=tmp0_1L
147 vpunpckhwd %1, %1, %7 ; %1=tmp0_1H
148 vpsrad %8, %8, (16-CONST_BITS) ; vpsrad %8,16 & vpslld %8,CONST_BITS
149 vpsrad %1, %1, (16-CONST_BITS) ; vpsrad %1,16 & vpslld %1,CONST_BITS
151 vpsubd %11, %8, %5 ; %11=tmp0_1L-tmp3_2L=tmp13_12L
152 vpaddd %9, %8, %5 ; %9=tmp0_1L+tmp3_2L=tmp10_11L
153 vpsubd %12, %1, %6 ; %12=tmp0_1H-tmp3_2H=tmp13_12H
154 vpaddd %10, %1, %6 ; %10=tmp0_1H+tmp3_2H=tmp10_11H
158 vpaddw %1, %4, %2 ; %1=in7_5+in3_1=z3_4
161 ; z5 = (z3 + z4) * 1.175875602;
162 ; z3 = z3 * -1.961570560; z4 = z4 * -0.390180644;
163 ; z3 += z5; z4 += z5;
165 ; (This implementation)
166 ; z3 = z3 * (1.175875602 - 1.961570560) + z4 * 1.175875602;
167 ; z4 = z3 * 1.175875602 + z4 * (1.175875602 - 0.390180644);
169 vperm2i128 %8, %1, %1, 0x01 ; %8=z4_3
170 vpunpcklwd %7, %1, %8 ; %7=z34_43L
171 vpunpckhwd %8, %1, %8 ; %8=z34_43H
172 vpmaddwd %7, %7, [rel PW_MF078_F117_F078_F117] ; %7=z3_4L
173 vpmaddwd %8, %8, [rel PW_MF078_F117_F078_F117] ; %8=z3_4H
176 ; z1 = tmp0 + tmp3; z2 = tmp1 + tmp2;
177 ; tmp0 = tmp0 * 0.298631336; tmp1 = tmp1 * 2.053119869;
178 ; tmp2 = tmp2 * 3.072711026; tmp3 = tmp3 * 1.501321110;
179 ; z1 = z1 * -0.899976223; z2 = z2 * -2.562915447;
180 ; tmp0 += z1 + z3; tmp1 += z2 + z4;
181 ; tmp2 += z2 + z3; tmp3 += z1 + z4;
183 ; (This implementation)
184 ; tmp0 = tmp0 * (0.298631336 - 0.899976223) + tmp3 * -0.899976223;
185 ; tmp1 = tmp1 * (2.053119869 - 2.562915447) + tmp2 * -2.562915447;
186 ; tmp2 = tmp1 * -2.562915447 + tmp2 * (3.072711026 - 2.562915447);
187 ; tmp3 = tmp0 * -0.899976223 + tmp3 * (1.501321110 - 0.899976223);
188 ; tmp0 += z3; tmp1 += z4;
189 ; tmp2 += z3; tmp3 += z4;
191 vperm2i128 %2, %2, %2, 0x01 ; %2=in1_3
192 vpunpcklwd %3, %4, %2 ; %3=in71_53L
193 vpunpckhwd %4, %4, %2 ; %4=in71_53H
195 vpmaddwd %5, %3, [rel PW_MF060_MF089_MF050_MF256] ; %5=tmp0_1L
196 vpmaddwd %6, %4, [rel PW_MF060_MF089_MF050_MF256] ; %6=tmp0_1H
197 vpaddd %5, %5, %7 ; %5=tmp0_1L+z3_4L=tmp0_1L
198 vpaddd %6, %6, %8 ; %6=tmp0_1H+z3_4H=tmp0_1H
200 vpmaddwd %3, %3, [rel PW_MF089_F060_MF256_F050] ; %3=tmp3_2L
201 vpmaddwd %4, %4, [rel PW_MF089_F060_MF256_F050] ; %4=tmp3_2H
202 vperm2i128 %7, %7, %7, 0x01 ; %7=z4_3L
203 vperm2i128 %8, %8, %8, 0x01 ; %8=z4_3H
204 vpaddd %7, %3, %7 ; %7=tmp3_2L+z4_3L=tmp3_2L
205 vpaddd %8, %4, %8 ; %8=tmp3_2H+z4_3H=tmp3_2H
207 ; -- Final output stage
209 vpaddd %1, %9, %7 ; %1=tmp10_11L+tmp3_2L=data0_1L
210 vpaddd %2, %10, %8 ; %2=tmp10_11H+tmp3_2H=data0_1H
211 vpaddd %1, %1, [rel PD_DESCALE_P %+ %13]
212 vpaddd %2, %2, [rel PD_DESCALE_P %+ %13]
213 vpsrad %1, %1, DESCALE_P %+ %13
214 vpsrad %2, %2, DESCALE_P %+ %13
215 vpackssdw %1, %1, %2 ; %1=data0_1
217 vpsubd %3, %9, %7 ; %3=tmp10_11L-tmp3_2L=data7_6L
218 vpsubd %4, %10, %8 ; %4=tmp10_11H-tmp3_2H=data7_6H
219 vpaddd %3, %3, [rel PD_DESCALE_P %+ %13]
220 vpaddd %4, %4, [rel PD_DESCALE_P %+ %13]
221 vpsrad %3, %3, DESCALE_P %+ %13
222 vpsrad %4, %4, DESCALE_P %+ %13
223 vpackssdw %4, %3, %4 ; %4=data7_6
225 vpaddd %7, %11, %5 ; %7=tmp13_12L+tmp0_1L=data3_2L
226 vpaddd %8, %12, %6 ; %8=tmp13_12H+tmp0_1H=data3_2H
227 vpaddd %7, %7, [rel PD_DESCALE_P %+ %13]
228 vpaddd %8, %8, [rel PD_DESCALE_P %+ %13]
229 vpsrad %7, %7, DESCALE_P %+ %13
230 vpsrad %8, %8, DESCALE_P %+ %13
231 vpackssdw %2, %7, %8 ; %2=data3_2
233 vpsubd %7, %11, %5 ; %7=tmp13_12L-tmp0_1L=data4_5L
234 vpsubd %8, %12, %6 ; %8=tmp13_12H-tmp0_1H=data4_5H
235 vpaddd %7, %7, [rel PD_DESCALE_P %+ %13]
236 vpaddd %8, %8, [rel PD_DESCALE_P %+ %13]
237 vpsrad %7, %7, DESCALE_P %+ %13
238 vpsrad %8, %8, DESCALE_P %+ %13
239 vpackssdw %3, %7, %8 ; %3=data4_5
242 ; --------------------------------------------------------------------------
246 GLOBAL_DATA(jconst_idct_islow_avx2)
248 EXTN(jconst_idct_islow_avx2):
250 PW_F130_F054_MF130_F054 times 4 dw (F_0_541 + F_0_765), F_0_541
251 times 4 dw (F_0_541 - F_1_847), F_0_541
252 PW_MF078_F117_F078_F117 times 4 dw (F_1_175 - F_1_961), F_1_175
253 times 4 dw (F_1_175 - F_0_390), F_1_175
254 PW_MF060_MF089_MF050_MF256 times 4 dw (F_0_298 - F_0_899), -F_0_899
255 times 4 dw (F_2_053 - F_2_562), -F_2_562
256 PW_MF089_F060_MF256_F050 times 4 dw -F_0_899, (F_1_501 - F_0_899)
257 times 4 dw -F_2_562, (F_3_072 - F_2_562)
258 PD_DESCALE_P1 times 8 dd 1 << (DESCALE_P1 - 1)
259 PD_DESCALE_P2 times 8 dd 1 << (DESCALE_P2 - 1)
260 PB_CENTERJSAMP times 32 db CENTERJSAMPLE
261 PW_1_NEG1 times 8 dw 1
266 ; --------------------------------------------------------------------------
270 ; Perform dequantization and inverse DCT on one block of coefficients.
273 ; jsimd_idct_islow_avx2(void *dct_table, JCOEFPTR coef_block,
274 ; JSAMPARRAY output_buf, JDIMENSION output_col)
277 ; r10 = jpeg_component_info *compptr
278 ; r11 = JCOEFPTR coef_block
279 ; r12 = JSAMPARRAY output_buf
280 ; r13d = JDIMENSION output_col
283 GLOBAL_FUNCTION(jsimd_idct_islow_avx2)
285 EXTN(jsimd_idct_islow_avx2):
287 mov rax, rsp ; rax = original rbp
288 mov rbp, rsp ; rbp = aligned rbp
292 ; ---- Pass 1: process columns.
294 %ifndef NO_ZERO_COLUMN_TEST_ISLOW_AVX2
295 mov eax, DWORD [DWBLOCK(1,0,r11,SIZEOF_JCOEF)]
296 or eax, DWORD [DWBLOCK(2,0,r11,SIZEOF_JCOEF)]
299 movdqa xmm0, XMMWORD [XMMBLOCK(1,0,r11,SIZEOF_JCOEF)]
300 movdqa xmm1, XMMWORD [XMMBLOCK(2,0,r11,SIZEOF_JCOEF)]
301 vpor xmm0, xmm0, XMMWORD [XMMBLOCK(3,0,r11,SIZEOF_JCOEF)]
302 vpor xmm1, xmm1, XMMWORD [XMMBLOCK(4,0,r11,SIZEOF_JCOEF)]
303 vpor xmm0, xmm0, XMMWORD [XMMBLOCK(5,0,r11,SIZEOF_JCOEF)]
304 vpor xmm1, xmm1, XMMWORD [XMMBLOCK(6,0,r11,SIZEOF_JCOEF)]
305 vpor xmm0, xmm0, XMMWORD [XMMBLOCK(7,0,r11,SIZEOF_JCOEF)]
306 vpor xmm1, xmm1, xmm0
307 vpacksswb xmm1, xmm1, xmm1
308 vpacksswb xmm1, xmm1, xmm1
313 ; -- AC terms all zero
315 movdqa xmm5, XMMWORD [XMMBLOCK(0,0,r11,SIZEOF_JCOEF)]
316 vpmullw xmm5, xmm5, XMMWORD [XMMBLOCK(0,0,r10,SIZEOF_ISLOW_MULT_TYPE)]
318 vpsllw xmm5, xmm5, PASS1_BITS
320 vpunpcklwd xmm4, xmm5, xmm5 ; xmm4=(00 00 01 01 02 02 03 03)
321 vpunpckhwd xmm5, xmm5, xmm5 ; xmm5=(04 04 05 05 06 06 07 07)
322 vinserti128 ymm4, ymm4, xmm5, 1
324 vpshufd ymm0, ymm4, 0x00 ; ymm0=col0_4=(00 00 00 00 00 00 00 00 04 04 04 04 04 04 04 04)
325 vpshufd ymm1, ymm4, 0x55 ; ymm1=col1_5=(01 01 01 01 01 01 01 01 05 05 05 05 05 05 05 05)
326 vpshufd ymm2, ymm4, 0xAA ; ymm2=col2_6=(02 02 02 02 02 02 02 02 06 06 06 06 06 06 06 06)
327 vpshufd ymm3, ymm4, 0xFF ; ymm3=col3_7=(03 03 03 03 03 03 03 03 07 07 07 07 07 07 07 07)
333 vmovdqu ymm4, YMMWORD [YMMBLOCK(0,0,r11,SIZEOF_JCOEF)] ; ymm4=in0_1
334 vmovdqu ymm5, YMMWORD [YMMBLOCK(2,0,r11,SIZEOF_JCOEF)] ; ymm5=in2_3
335 vmovdqu ymm6, YMMWORD [YMMBLOCK(4,0,r11,SIZEOF_JCOEF)] ; ymm6=in4_5
336 vmovdqu ymm7, YMMWORD [YMMBLOCK(6,0,r11,SIZEOF_JCOEF)] ; ymm7=in6_7
337 vpmullw ymm4, ymm4, YMMWORD [YMMBLOCK(0,0,r10,SIZEOF_ISLOW_MULT_TYPE)]
338 vpmullw ymm5, ymm5, YMMWORD [YMMBLOCK(2,0,r10,SIZEOF_ISLOW_MULT_TYPE)]
339 vpmullw ymm6, ymm6, YMMWORD [YMMBLOCK(4,0,r10,SIZEOF_ISLOW_MULT_TYPE)]
340 vpmullw ymm7, ymm7, YMMWORD [YMMBLOCK(6,0,r10,SIZEOF_ISLOW_MULT_TYPE)]
342 vperm2i128 ymm0, ymm4, ymm6, 0x20 ; ymm0=in0_4
343 vperm2i128 ymm1, ymm5, ymm4, 0x31 ; ymm1=in3_1
344 vperm2i128 ymm2, ymm5, ymm7, 0x20 ; ymm2=in2_6
345 vperm2i128 ymm3, ymm7, ymm6, 0x31 ; ymm3=in7_5
347 dodct ymm0, ymm1, ymm2, ymm3, ymm4, ymm5, ymm6, ymm7, ymm8, ymm9, ymm10, ymm11, 1
348 ; ymm0=data0_1, ymm1=data3_2, ymm2=data4_5, ymm3=data7_6
350 dotranspose ymm0, ymm1, ymm2, ymm3, ymm4, ymm5, ymm6, ymm7
351 ; ymm0=data0_4, ymm1=data1_5, ymm2=data2_6, ymm3=data3_7
355 ; -- Prefetch the next coefficient block
357 prefetchnta [r11 + DCTSIZE2*SIZEOF_JCOEF + 0*32]
358 prefetchnta [r11 + DCTSIZE2*SIZEOF_JCOEF + 1*32]
359 prefetchnta [r11 + DCTSIZE2*SIZEOF_JCOEF + 2*32]
360 prefetchnta [r11 + DCTSIZE2*SIZEOF_JCOEF + 3*32]
362 ; ---- Pass 2: process rows.
364 vperm2i128 ymm4, ymm3, ymm1, 0x31 ; ymm3=in7_5
365 vperm2i128 ymm1, ymm3, ymm1, 0x20 ; ymm1=in3_1
367 dodct ymm0, ymm1, ymm2, ymm4, ymm3, ymm5, ymm6, ymm7, ymm8, ymm9, ymm10, ymm11, 2
368 ; ymm0=data0_1, ymm1=data3_2, ymm2=data4_5, ymm4=data7_6
370 dotranspose ymm0, ymm1, ymm2, ymm4, ymm3, ymm5, ymm6, ymm7
371 ; ymm0=data0_4, ymm1=data1_5, ymm2=data2_6, ymm4=data3_7
373 vpacksswb ymm0, ymm0, ymm1 ; ymm0=data01_45
374 vpacksswb ymm1, ymm2, ymm4 ; ymm1=data23_67
375 vpaddb ymm0, ymm0, [rel PB_CENTERJSAMP]
376 vpaddb ymm1, ymm1, [rel PB_CENTERJSAMP]
378 vextracti128 xmm6, ymm1, 1 ; xmm3=data67
379 vextracti128 xmm4, ymm0, 1 ; xmm2=data45
380 vextracti128 xmm2, ymm1, 0 ; xmm1=data23
381 vextracti128 xmm0, ymm0, 0 ; xmm0=data01
383 vpshufd xmm1, xmm0, 0x4E ; xmm1=(10 11 12 13 14 15 16 17 00 01 02 03 04 05 06 07)
384 vpshufd xmm3, xmm2, 0x4E ; xmm3=(30 31 32 33 34 35 36 37 20 21 22 23 24 25 26 27)
385 vpshufd xmm5, xmm4, 0x4E ; xmm5=(50 51 52 53 54 55 56 57 40 41 42 43 44 45 46 47)
386 vpshufd xmm7, xmm6, 0x4E ; xmm7=(70 71 72 73 74 75 76 77 60 61 62 63 64 65 66 67)
392 mov rdx, JSAMPROW [r12+0*SIZEOF_JSAMPROW] ; (JSAMPLE *)
393 mov rsi, JSAMPROW [r12+1*SIZEOF_JSAMPROW] ; (JSAMPLE *)
394 movq XMM_MMWORD [rdx+rax*SIZEOF_JSAMPLE], xmm0
395 movq XMM_MMWORD [rsi+rax*SIZEOF_JSAMPLE], xmm1
397 mov rdx, JSAMPROW [r12+2*SIZEOF_JSAMPROW] ; (JSAMPLE *)
398 mov rsi, JSAMPROW [r12+3*SIZEOF_JSAMPROW] ; (JSAMPLE *)
399 movq XMM_MMWORD [rdx+rax*SIZEOF_JSAMPLE], xmm2
400 movq XMM_MMWORD [rsi+rax*SIZEOF_JSAMPLE], xmm3
402 mov rdx, JSAMPROW [r12+4*SIZEOF_JSAMPROW] ; (JSAMPLE *)
403 mov rsi, JSAMPROW [r12+5*SIZEOF_JSAMPROW] ; (JSAMPLE *)
404 movq XMM_MMWORD [rdx+rax*SIZEOF_JSAMPLE], xmm4
405 movq XMM_MMWORD [rsi+rax*SIZEOF_JSAMPLE], xmm5
407 mov rdx, JSAMPROW [r12+6*SIZEOF_JSAMPROW] ; (JSAMPLE *)
408 mov rsi, JSAMPROW [r12+7*SIZEOF_JSAMPROW] ; (JSAMPLE *)
409 movq XMM_MMWORD [rdx+rax*SIZEOF_JSAMPLE], xmm6
410 movq XMM_MMWORD [rsi+rax*SIZEOF_JSAMPLE], xmm7
417 ; For some reason, the OS X linker does not honor the request to align the
418 ; segment unless we do this.