mirror/gmsm
1
0
Fork 0
mirror of https://github.com/emmansun/gmsm.git synced 2025-05-19 15:36:18 +08:00
Code Issues Packages Projects Releases Wiki Activity

Updated SM2 MFMM (2) (markdown)

Sun Yimin 2024-02-22 11:04:39 +08:00
parent 672b1e4e92
commit aca73e2d79
1 changed files with 8 additions and 6 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

14
SM2-MFMM-(2).md

@ -97,6 +97,8 @@ $t_2=t_2 - a_1$
$t_3=t_3 - a_0$
$t_0=t_0 - a_1$
**减法显然是安全的（因为第四步的结果显然是>=0的，而且为零的情况仅限于 $t_0==0$ 的情况 ），所以调整为先做减法，再做加法，确保第四步加法不会产生进位。**。
伪代码：
```asm
\ // First reduction step, [p3, p2, p1, p0] = [1, -0x100000000, 0, (1 - 0x100000000), -1]
@ -104,17 +106,17 @@ $t_0=t_0 - a_1$
MOVQ acc0, DX \
SHLQ $32, AX \ // AX = L(acc0 * 2^32), low part
SHRQ $32, DX \ // DX = H(acc0 * 2^32), high part
\ // calculate the positive part first: [1, 0, 0, 1] * acc0 + [0, acc3, acc2, acc1],
\ // due to (-1) * acc0 + acc0 == 0, so last lowest lamb 0 is dropped directly, no carry.
ADDQ acc0, acc1 \ // acc1' = L (acc0 + acc1)
ADCQ $0, acc2 \ // acc2' = acc2 + carry1
ADCQ $0, acc3 \ // acc3' = acc3 + carry2
ADCQ $0, acc0 \ // acc0' = acc0 + carry3
\// calculate the negative part: [0, -0x100000000, 0, -0x100000000] * acc0
SUBQ AX, acc1 \
SBBQ DX, acc2 \
SBBQ AX, acc3 \
SBBQ DX, acc0 \
\ // calculate the positive part: [1, 0, 0, 1] * acc0 + [0, acc3, acc2, acc1],
\ // due to (-1) * acc0 + acc0 == 0, so last lowest lamb 0 is dropped directly, no carry.
ADDQ acc0, acc1 \ // acc1' = L (acc0 + acc1)
ADCQ $0, acc2 \ // acc2' = acc2 + carry1
ADCQ $0, acc3 \ // acc3' = acc3 + carry2
ADCQ $0, acc0 \ // acc0' = acc0 + carry3
```
移位: 2
加法：4