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Diffstat (limited to 'ppc/sha1ppc.S')
| -rw-r--r-- | ppc/sha1ppc.S | 224 |
1 files changed, 224 insertions, 0 deletions
diff --git a/ppc/sha1ppc.S b/ppc/sha1ppc.S new file mode 100644 index 0000000..f132696 --- /dev/null +++ b/ppc/sha1ppc.S @@ -0,0 +1,224 @@ +/* + * SHA-1 implementation for PowerPC. + * + * Copyright (C) 2005 Paul Mackerras <paulus@samba.org> + */ + +/* + * PowerPC calling convention: + * %r0 - volatile temp + * %r1 - stack pointer. + * %r2 - reserved + * %r3-%r12 - Incoming arguments & return values; volatile. + * %r13-%r31 - Callee-save registers + * %lr - Return address, volatile + * %ctr - volatile + * + * Register usage in this routine: + * %r0 - temp + * %r3 - argument (pointer to 5 words of SHA state) + * %r4 - argument (pointer to data to hash) + * %r5 - Constant K in SHA round (initially number of blocks to hash) + * %r6-%r10 - Working copies of SHA variables A..E (actually E..A order) + * %r11-%r26 - Data being hashed W[]. + * %r27-%r31 - Previous copies of A..E, for final add back. + * %ctr - loop count + */ + + +/* + * We roll the registers for A, B, C, D, E around on each + * iteration; E on iteration t is D on iteration t+1, and so on. + * We use registers 6 - 10 for this. (Registers 27 - 31 hold + * the previous values.) + */ +#define RA(t) (((t)+4)%5+6) +#define RB(t) (((t)+3)%5+6) +#define RC(t) (((t)+2)%5+6) +#define RD(t) (((t)+1)%5+6) +#define RE(t) (((t)+0)%5+6) + +/* We use registers 11 - 26 for the W values */ +#define W(t) ((t)%16+11) + +/* Register 5 is used for the constant k */ + +/* + * The basic SHA-1 round function is: + * E += ROTL(A,5) + F(B,C,D) + W[i] + K; B = ROTL(B,30) + * Then the variables are renamed: (A,B,C,D,E) = (E,A,B,C,D). + * + * Every 20 rounds, the function F() and the constant K changes: + * - 20 rounds of f0(b,c,d) = "bit wise b ? c : d" = (^b & d) + (b & c) + * - 20 rounds of f1(b,c,d) = b^c^d = (b^d)^c + * - 20 rounds of f2(b,c,d) = majority(b,c,d) = (b&d) + ((b^d)&c) + * - 20 more rounds of f1(b,c,d) + * + * These are all scheduled for near-optimal performance on a G4. + * The G4 is a 3-issue out-of-order machine with 3 ALUs, but it can only + * *consider* starting the oldest 3 instructions per cycle. So to get + * maximum performance out of it, you have to treat it as an in-order + * machine. Which means interleaving the computation round t with the + * computation of W[t+4]. + * + * The first 16 rounds use W values loaded directly from memory, while the + * remaining 64 use values computed from those first 16. We preload + * 4 values before starting, so there are three kinds of rounds: + * - The first 12 (all f0) also load the W values from memory. + * - The next 64 compute W(i+4) in parallel. 8*f0, 20*f1, 20*f2, 16*f1. + * - The last 4 (all f1) do not do anything with W. + * + * Therefore, we have 6 different round functions: + * STEPD0_LOAD(t,s) - Perform round t and load W(s). s < 16 + * STEPD0_UPDATE(t,s) - Perform round t and compute W(s). s >= 16. + * STEPD1_UPDATE(t,s) + * STEPD2_UPDATE(t,s) + * STEPD1(t) - Perform round t with no load or update. + * + * The G5 is more fully out-of-order, and can find the parallelism + * by itself. The big limit is that it has a 2-cycle ALU latency, so + * even though it's 2-way, the code has to be scheduled as if it's + * 4-way, which can be a limit. To help it, we try to schedule the + * read of RA(t) as late as possible so it doesn't stall waiting for + * the previous round's RE(t-1), and we try to rotate RB(t) as early + * as possible while reading RC(t) (= RB(t-1)) as late as possible. + */ + +/* the initial loads. */ +#define LOADW(s) \ + lwz W(s),(s)*4(%r4) + +/* + * Perform a step with F0, and load W(s). Uses W(s) as a temporary + * before loading it. + * This is actually 10 instructions, which is an awkward fit. + * It can execute grouped as listed, or delayed one instruction. + * (If delayed two instructions, there is a stall before the start of the + * second line.) Thus, two iterations take 7 cycles, 3.5 cycles per round. + */ +#define STEPD0_LOAD(t,s) \ +add RE(t),RE(t),W(t); andc %r0,RD(t),RB(t); and W(s),RC(t),RB(t); \ +add RE(t),RE(t),%r0; rotlwi %r0,RA(t),5; rotlwi RB(t),RB(t),30; \ +add RE(t),RE(t),W(s); add %r0,%r0,%r5; lwz W(s),(s)*4(%r4); \ +add RE(t),RE(t),%r0 + +/* + * This is likewise awkward, 13 instructions. However, it can also + * execute starting with 2 out of 3 possible moduli, so it does 2 rounds + * in 9 cycles, 4.5 cycles/round. + */ +#define STEPD0_UPDATE(t,s,loadk...) \ +add RE(t),RE(t),W(t); andc %r0,RD(t),RB(t); xor W(s),W((s)-16),W((s)-3); \ +add RE(t),RE(t),%r0; and %r0,RC(t),RB(t); xor W(s),W(s),W((s)-8); \ +add RE(t),RE(t),%r0; rotlwi %r0,RA(t),5; xor W(s),W(s),W((s)-14); \ +add RE(t),RE(t),%r5; loadk; rotlwi RB(t),RB(t),30; rotlwi W(s),W(s),1; \ +add RE(t),RE(t),%r0 + +/* Nicely optimal. Conveniently, also the most common. */ +#define STEPD1_UPDATE(t,s,loadk...) \ +add RE(t),RE(t),W(t); xor %r0,RD(t),RB(t); xor W(s),W((s)-16),W((s)-3); \ +add RE(t),RE(t),%r5; loadk; xor %r0,%r0,RC(t); xor W(s),W(s),W((s)-8); \ +add RE(t),RE(t),%r0; rotlwi %r0,RA(t),5; xor W(s),W(s),W((s)-14); \ +add RE(t),RE(t),%r0; rotlwi RB(t),RB(t),30; rotlwi W(s),W(s),1 + +/* + * The naked version, no UPDATE, for the last 4 rounds. 3 cycles per. + * We could use W(s) as a temp register, but we don't need it. + */ +#define STEPD1(t) \ + add RE(t),RE(t),W(t); xor %r0,RD(t),RB(t); \ +rotlwi RB(t),RB(t),30; add RE(t),RE(t),%r5; xor %r0,%r0,RC(t); \ +add RE(t),RE(t),%r0; rotlwi %r0,RA(t),5; /* spare slot */ \ +add RE(t),RE(t),%r0 + +/* + * 14 instructions, 5 cycles per. The majority function is a bit + * awkward to compute. This can execute with a 1-instruction delay, + * but it causes a 2-instruction delay, which triggers a stall. + */ +#define STEPD2_UPDATE(t,s,loadk...) \ +add RE(t),RE(t),W(t); and %r0,RD(t),RB(t); xor W(s),W((s)-16),W((s)-3); \ +add RE(t),RE(t),%r0; xor %r0,RD(t),RB(t); xor W(s),W(s),W((s)-8); \ +add RE(t),RE(t),%r5; loadk; and %r0,%r0,RC(t); xor W(s),W(s),W((s)-14); \ +add RE(t),RE(t),%r0; rotlwi %r0,RA(t),5; rotlwi W(s),W(s),1; \ +add RE(t),RE(t),%r0; rotlwi RB(t),RB(t),30 + +#define STEP0_LOAD4(t,s) \ + STEPD0_LOAD(t,s); \ + STEPD0_LOAD((t+1),(s)+1); \ + STEPD0_LOAD((t)+2,(s)+2); \ + STEPD0_LOAD((t)+3,(s)+3) + +#define STEPUP4(fn, t, s, loadk...) \ + STEP##fn##_UPDATE(t,s,); \ + STEP##fn##_UPDATE((t)+1,(s)+1,); \ + STEP##fn##_UPDATE((t)+2,(s)+2,); \ + STEP##fn##_UPDATE((t)+3,(s)+3,loadk) + +#define STEPUP20(fn, t, s, loadk...) \ + STEPUP4(fn, t, s,); \ + STEPUP4(fn, (t)+4, (s)+4,); \ + STEPUP4(fn, (t)+8, (s)+8,); \ + STEPUP4(fn, (t)+12, (s)+12,); \ + STEPUP4(fn, (t)+16, (s)+16, loadk) + + .globl sha1_core +sha1_core: + stwu %r1,-80(%r1) + stmw %r13,4(%r1) + + /* Load up A - E */ + lmw %r27,0(%r3) + + mtctr %r5 + +1: + LOADW(0) + lis %r5,0x5a82 + mr RE(0),%r31 + LOADW(1) + mr RD(0),%r30 + mr RC(0),%r29 + LOADW(2) + ori %r5,%r5,0x7999 /* K0-19 */ + mr RB(0),%r28 + LOADW(3) + mr RA(0),%r27 + + STEP0_LOAD4(0, 4) + STEP0_LOAD4(4, 8) + STEP0_LOAD4(8, 12) + STEPUP4(D0, 12, 16,) + STEPUP4(D0, 16, 20, lis %r5,0x6ed9) + + ori %r5,%r5,0xeba1 /* K20-39 */ + STEPUP20(D1, 20, 24, lis %r5,0x8f1b) + + ori %r5,%r5,0xbcdc /* K40-59 */ + STEPUP20(D2, 40, 44, lis %r5,0xca62) + + ori %r5,%r5,0xc1d6 /* K60-79 */ + STEPUP4(D1, 60, 64,) + STEPUP4(D1, 64, 68,) + STEPUP4(D1, 68, 72,) + STEPUP4(D1, 72, 76,) + addi %r4,%r4,64 + STEPD1(76) + STEPD1(77) + STEPD1(78) + STEPD1(79) + + /* Add results to original values */ + add %r31,%r31,RE(0) + add %r30,%r30,RD(0) + add %r29,%r29,RC(0) + add %r28,%r28,RB(0) + add %r27,%r27,RA(0) + + bdnz 1b + + /* Save final hash, restore registers, and return */ + stmw %r27,0(%r3) + lmw %r13,4(%r1) + addi %r1,%r1,80 + blr |