关于430硬件乘法器

只看该作者 · 2017-2-28 21:00

430硬件乘法的乘累加器不知道怎么用求一段C例程；
官方例程也有看似乎都没有说到乘累加怎么用哦！想在FFT里面优化一下程序可能会用到乘累加。

只看该作者 · 2017-2-28 21:09

.无符号数乘加操作 result="n1"*n2+n3*n4。第一操作数n1（16位无符号）赋给MPY寄存器，第二操作数n2（16位无符号）赋给OP2寄存器，第三操作数n3（16位无符号）赋给MAC寄存器，第四操作数n4（16位无符号）赋给OP2寄存器，结果result（32位无符号）就可以在RESLO（低16位）和RESHI（高165位）中读取。SUMEXT寄存器中保存进位标志。
代码如下：
  MPY = n1;                            // Load first operand -unsigned mult
  OP2 = n2;                            // Load second operand
  MAC = n3; // Load 3rd operand -unsigned mult
  OP2 = n4; // Load 4rd operand
  result = RESHI;                         // Load RESHI word result
  result = (result<<16)|RESLO;             // Shift RESHI left and concat with
这是16位的，32位的类似

只看该作者 · 2017-2-28 21:24

//******************************************************************************
// MSP430x26x Demo - 8x8 Signed Multiply Accumulate
//
// Description: Hardware multiplier is used to multiply two numbers.
// The calculation is automatically initiated after the second operand is
// loaded.  A second multiply accumulate operation is performed after that.
// Results are stored in RESLO and RESHI.  SUMEXT contains the extended sign of
// result.
// ACLK = 32.768kHz, MCLK = SMCLK = default DCO
//
//          MSP430F261x/241x
//          -----------------
//       /|\|                |
//       | |                |
//       --|RST             |
//          |                |
//          |                |
//
//  B. Nisarga
//  Texas Instruments Inc.
//  September 2007
//  Built with CCE Version: 3.2.0 and IAR Embedded Workbench Version: 3.42A
//******************************************************************************
#include

void main(void)
{
  unsigned char value1,value2;

  WDTCTL = WDTPW+WDTHOLD;                // Stop WDT

  MPY = 0x1234;                            // Load 1st operand - unsigned mult
  OP2 = 0x5678;                            // Load second operand

  value1 = 0x12;                         // Load first operand - signed MAC
  value2 = 0x96;                         // Load second operand

  // Sign-extend the values
  if (value1 >=0x80)
MACS = 0xFF00 | value1;
  else
MACS = value1;
  if (value2 >=0x80)
OP2 = 0xFF00 | value2;
  else
OP2 = value2;

  _BIS_SR(LPM4_bits);                      // LPM4
}