Computer Organization and Design assignements
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204 lignes
6.4 KiB

  1. .text
  2. .globl main
  3. main:
  4. # intro - stack-frame
  5. addi $sp, $sp, -8 # main
  6. sw $ra, 4($sp)
  7. sw $fp, 0($sp)
  8. addi $fp, $sp, 0 # stack arguments (no)
  9. li $a0, 0xbf800000 # <-- test case goes here
  10. li $a1, 0x3f800000
  11. jal multFloat
  12. # epilogue - stack-frame
  13. lw $fp, 0($sp)
  14. lw $ra, 4($sp)
  15. addi $sp, $sp, 8
  16. jr $ra
  17. #
  18. # encodeFloat (sign, exp, mant)
  19. # Arguments
  20. # $a0: The sign
  21. # $a1: The exponent without the bias
  22. # $a2: The normalized mantissa 24bit, with the implied bit
  23. # Retuen
  24. # $v0: The floating point word
  25. encodeFloat:
  26. # intro - stack-frame
  27. addi $sp, $sp, -8 # encodeFloat
  28. sw $ra, 4($sp)
  29. sw $fp, 0($sp)
  30. addi $fp, $sp, 0 # stack arguments (no)
  31. sll $v0, $a0, 31 # v0 = sign << 31
  32. addi $a1, $a1, 127 # v0 |= (exp + offset) << 23
  33. sll $a1, $a1, 23
  34. or $v0, $v0, $a1
  35. li $t0, 0x7FFFFF # v0 |= (mant & 0x7FFFFF);
  36. and $a2, $a2, $t0
  37. or $v0, $v0, $a2
  38. # epilogue - stack-frame
  39. lw $fp, 0($sp)
  40. lw $ra, 4($sp)
  41. addi $sp, $sp, 8
  42. jr $ra
  43. #
  44. # decodeFloat(number)
  45. # arguments
  46. # $a0 : 32bit floating point
  47. # return
  48. # $v0 : sign unsigned int 0 or 1
  49. # $v1 : exponent the value of bits(30:24) - 127, signed integer
  50. # $a1 : mantissa with bits 1 followed by bits (22:0)
  51. decodeFloat:
  52. # intro - stack-frame
  53. addi $sp, $sp, -8 # decodeFloat
  54. sw $ra, 4($sp)
  55. sw $fp, 0($sp)
  56. addi $fp, $sp, 0 # stack arguments (no)
  57. srl $v0, $a0, 31 # sign[v0] = a0 >> 31;
  58. srl $t0, $a0, 23 # exp[v1] = ((a0 >> 23) & 0xFF) - 127;
  59. and $t0, $t0, 0xFF
  60. addi $v1, $t0, -127
  61. li $t0, 0x7FFFFF # Mantissa[a1] = (a0 & 0x7FFFFF) | 0x800000;
  62. and $a1, $a0, $t0
  63. li $t0, 0x800000
  64. or $a1, $a1, $t0
  65. # epilogue - stack-frame
  66. lw $fp, 0($sp)
  67. lw $ra, 4($sp)
  68. addi $sp, $sp, 8
  69. jr $ra # return
  70. #
  71. # multFloat(f1, f2)
  72. # arguments
  73. # $a0 : 32bit floating point 1
  74. # $a1 : 32bit floating point 2
  75. # return
  76. # $v0 : 32bit floating point multiplication result
  77. multFloat:
  78. # s0: sign and argument 2
  79. # s1: exp
  80. # s2: mantissa
  81. # intro - stack-frame
  82. addi $sp, $sp, -20 # multFloat
  83. sw $ra, 16($sp)
  84. sw $fp, 12($sp)
  85. sw $s2, 8($sp)
  86. sw $s1, 4($sp)
  87. sw $s0, 0($sp)
  88. addi $fp, $sp, 0 # stack arguments (no)
  89. move $s0, $a1 # save 2nd argument
  90. jal decodeFloat # decodeFloat(arg1) : [v0, v1, a1] <- [s, e, m]
  91. move $t0, $s0 # $s0 change variable to $t0
  92. move $s0, $v0 # load return values to variable regs
  93. move $s1, $v1
  94. move $s2, $a1
  95. move $a0, $t0 # load back argument 2
  96. jal decodeFloat # decodeFloat(arg2) : [v0, v1, a1] <- [s, e, m]
  97. xor $s0, $s0, $v0 # sign = s1 ^ s2
  98. add $s1, $s1, $v1 # exp = e1 + e2
  99. multu $s2, $a1 # mantissa = m1 * m2
  100. mfhi $t4 # t4: mantissa-hi
  101. mflo $t3 # t3: mantissa-low
  102. addi $s2, $zero, 0
  103. li $t9, 0x8000 # if (HI & (1<<15))
  104. and $t8, $t9, $t4
  105. beq $t8, $zero, _multf_l0
  106. # (true)not zero, 48-bits result, normalize
  107. sll $s2, $t4, 8 # mant = HI << 8
  108. srl $t9, $t3, 24 # mant |= LOW >> (32-8)
  109. or $s2, $s2, $t9
  110. addi $s1, $s1, 1 # ++exp, normalize
  111. li $t9, 0x800000 # if (ml & (1<<23)), rounding check
  112. and $t8, $t9, $t3
  113. beq $t8, $zero, _multf_l0_end
  114. addi $s2, $s2, 1 # ++mant, round-up
  115. j _multf_l0_end
  116. _multf_l0:
  117. # (false)zero, 47-bits result
  118. sll $s2, $t4, 9 # mant = HI << 9
  119. srl $t9, $t3, 23 # mant |= LOW >> (32-9)
  120. or $s2, $s2, $t9
  121. li $t9, 0x400000 # if (ml & (1<<22)), rounding check
  122. and $t8, $t9, $t3
  123. beq $t8, $zero, _multf_l0_end
  124. addi $s2, $s2, 1 # ++mant, round-up
  125. _multf_l0_end:
  126. move $a0, $s0
  127. move $a1, $s1
  128. move $a2, $s2
  129. jal encodeFloat # encodeFloat(s, e, m) : float(v0)
  130. # epilogue - stack-frame
  131. lw $s0, 0($sp)
  132. lw $s1, 4($sp)
  133. lw $s2, 8($sp)
  134. lw $fp, 12($sp)
  135. lw $ra, 16($sp)
  136. addi $sp, $sp, 20
  137. jr $ra # return
  138. #
  139. # fprod(vector, size)
  140. # Calculates the product x[0] * x[1] * x[2] * ... * x[n-1] as
  141. # Left fold of product operator on a vector of numbers - foldl(*, x)
  142. #
  143. # Arguments
  144. # $a0: Pointer to array x[] in RAM
  145. # $a1: Number of elements
  146. # Return
  147. # $v0: The product
  148. fprod:
  149. # intro - stack-frame
  150. addi $sp, $sp, -20 # fprod
  151. sw $ra, 16($sp)
  152. sw $fp, 12($sp)
  153. sw $s2, 8($sp)
  154. sw $s1, 4($sp)
  155. sw $s0, 0($sp)
  156. addi $fp, $sp, 0 # stack arguments (no)
  157. # keep input arguments
  158. move $s0, $a0 # x[]
  159. move $s1, $a1 # n
  160. lw $v0, 0($s0) # Acc = *x
  161. addi $s2, $zero, 1 # i=1
  162. _fprod_loop: # for ( ; i<n ; ) {
  163. bge $s2, $s1, _fprod_loop_end
  164. addi $s0, $s0, 4 # a0 <- *++x
  165. lw $a0, 0($s0)
  166. move $a1, $v0 # a1 <- use prev result
  167. jal multFloat
  168. addi $s2, $s2, 1 # ++i
  169. j _fprod_loop # }
  170. _fprod_loop_end:
  171. # epilogue - stack-frame
  172. lw $s0, 0($sp)
  173. lw $s1, 4($sp)
  174. lw $s2, 8($sp)
  175. lw $fp, 12($sp)
  176. lw $ra, 16($sp)
  177. addi $sp, $sp, 20
  178. jr $ra # return