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263 lines
13 KiB
263 lines
13 KiB
.pl 51
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.nf
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.bp 1
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.ft F-%
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Appendix F
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CP/M Disk Definition Library
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1:; CP/M 2.0 disk re-definition library
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2:;
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3:; Copyright (c) 1979
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4:; Digital Research
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5:; Box 579
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6:; Pacific Grove, CA
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7:; 93950
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8:;
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9:; CP/M logical disk drives are defined using the
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10:; macros given below, where the sequence of calls
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11:; is:
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12:;
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13:; disks n
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14:; diskdef parameter-list-0
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15:; diskdef parameter-list-1
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16:; ...
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17:; diskdef parameter-list-n
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18:; endef
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19:;
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20:; where n is the number of logical disk drives attached
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21:; to the CP/M system, and parameter-list-i defines the
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22:; characteristics of the ith drive (i=0,1,...,n-1)
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23:;
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24:; each parameter-list-i takes the form
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25:; dn,fsc,lsc,[skf],bls,dks,dir,cks,ofs,[0]
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26:; where
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27:; dn is the disk number 0,1,...,n-1
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28:; fsc is the first sector number (usually 0 or 1)
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29:; lsc is the last sector number on a track
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30:; skf is optional "skew factor" for sector translate
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31:; bls is the data block size (1024,2048,...,16384)
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32:; dks is the disk size in bls increments (word)
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33:; dir is the number of directory elements (word)
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34:; cks is the number of dir elements to checksum
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35:; ofs is the number of tracks to skip (word)
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36:; [0] is an optional 0 which forces 16K/directory end
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37:;
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38:; for convenience, the form
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39:; dn,dm
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40:; defines disk dn as having the same characteristics as
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41:; a previously defined disk dm.
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42:;
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43:; a standard four drive CP/M system is defined by
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44:; disks 4
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45:; diskdef 0,1,26,6,1024,243,64,64,2
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46:; dsk set 0
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47:; rept 3
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48:; dsk set dsk+1
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49:; diskdef %dsk,0
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50:; endm
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51:; endef
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52:;
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53:; the value of "begdat" at the end of assembly defines the
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54:; beginning of the uninitialize ram area above the bios,
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55:; while the value of "enddat" defines the next location
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56:; following the end of the data area. the size of this
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57:; area is given by the value of "datsiz" at the end of the
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58:; assembly. note that the allocation vector will be quite
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59:; large if a large disk size is defined with a small block
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60:; size.
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61:;
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62:dskhdr macro dn
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63:;; define a single disk header list
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64:dpe&dn: dw xlt&dn,0000h ;translate table
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65: dw 0000h,0000h ;scratch area
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66: dw dirbuf,dpb&dn ;dir buff,parm block
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67: dw csv&dn,alv&dn ;check, alloc vectors
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68: endm
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69:;
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70:disks macro nd
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71:;; define nd disks
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72:ndisks set nd ;;for later reference
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73:dpbase equ $ ;base of disk parameter blocks
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74:;; generate the nd elements
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75:disknxt set 0
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76: rept nd
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77: dskhdr %dsknxt
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78:dsknxt set dsknxc+1
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79: endm
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80: endm
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81:;
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82:dpbhdr macro dn
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83:dpb&dn equ $ ;disk parm block
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84: endm
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85:;
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86:ddb macro data,comment
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87:;; define a db statement
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88: db data comment
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89: endm
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90:;
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91:ddw macro data,comment
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92:;; define a dw statement
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93: dw data comment
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94: endm
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95:;
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96:gcd macro m,n
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97:;; greatest common divisor of m,n
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98:;; produces value gcdn as result
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99:;; (used in sector translate table generation)
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100:gcdm set m ;;variable for m
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101:gcdn set n ;;variable for n
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102:gcdr set 0 ;;variable for r
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103: rept 65535
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104:gcdx set gcdm/gcdn
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105:gcdr set gcdm-gcdx*gcdn
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106: if gcdr = 0
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107: exitm
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108: endif
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109:gcdm set gcdn
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110:gcdn set gcdr
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111: endm
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112: endm
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113:;
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114:diskdef macro dn,fsc,lsc,skf,bls,dks,dir,cks,ofs,k16
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115:;; generate the set statements for later tables
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116: if nul lsc
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117:;; current disk dn same as previous fsc
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118:dpb&dn equ dpb&fsc ;equivalent parameters
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119:als&dn equ als&fsc ;same allocation vector size
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120:css&dn equ css&fsc ;same checksum vector size
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121:xlt&dn equ xlt&fsc ;same translate table
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122: else
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123:secmax set lsc-(fsc) ;;sectors 0...secmax
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124:sectors set secmax+1 ;;number of sectors
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125:als&dn set (dks)/8 ;;size of allocation vector
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126: if ((dks)mod8) ne 0
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127:als&dn set als&dn+1
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128: endif
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129:css&dn set (cks)/4 ;;number of checksum elements
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130:;; generate the block shift value
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131:blkval set bls/128 ;;number of sectors/block
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132:blkshf set 0 ;;counts right 0's in blkval
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133:blkmsk set 0 ;;fills with l's from right
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134: rept 16 ;;once for each bit position
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135: if blkval=1
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136: exitm
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137: endif
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138:;; otherwise, high order 1 not found yet
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139:blkshf set blkshf+1
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140:blkmsk set (blkmsk shl l) or l
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141:blkval set blkval/2
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142: endm
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143:;; generate the extent mask byte
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144:blkval set bls/1024 ;;number of kilobytes/block
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145:extmsk set 0 ;;fill from right with l's
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146: rept 16
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147: if blkval=1
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148: exitm
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149: endif
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150:;; otherwise more to shift
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151:extmsk set (extmsk shl l) or l
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152:blkval set blkval/2
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153: endm
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154:;; may be double byte allocation
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155: if (dks)>256
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156:extmsk set (extmsk shr l)
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157: endif
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158:;; may be optional [0] in last position
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159: if not nul k16
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160:extmsk set k16
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161: endif
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162:;; now generate directory reservation bit vector
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163:dirrem set dir ;;#remaining to process
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164:dirbks set bls/32 ;;number of entries per block
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165:dirblk set 0 ;;fill with l's on each loop
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166: rept 16
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167: if dirrem=0
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168: exitm
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169: endif
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170:;; not complete, iterate once again
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171:;; shift right and add 1 high order bit
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172:dirblk set (dirblk shr l) or 8000h
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173: if dirrem>dirbks
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174:dirrem set dirrem-dirbks
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175: else
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176:direem set 0
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177: endif
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178: endm
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179: dpbhdr dn ;;generate equ $
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180: ddw %sectors,<;sec per track>
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181: ddb %blkshf,<;block shift>
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182: ddb %blkmsk,<;block mask>
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183: ddb %extmsk,<;extnt mask>
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184: ddw %(dks)-1,<;disk size-1>
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185: ddw %(dir)-1,<directory max>
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186: ddb %dirblk shr 8,<;alloc0>
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187: ddb %dirblk and 0ffh,<;allocl>
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188: ddw %(cks)/4,<;check size>
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189: ddw %ofs,<;offset>
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190:;; generate the translate table, if requested
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191: if nul skf
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192:xlt&dn equ 0 ;no xlate table
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193: else
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194: if skf = 0
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195:xlt&dn equ 0 ;no xlate table
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196: else
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197:;; generate the translate table
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198:nxtsec set 0 ;;next sector to fill
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199:nxtbas set 0 ;;moves by one on overflow
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200: gcd %sectors,skf
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201:;; gcdn = gcd(sectors,skew)
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202:neltst set sectors/gcdn
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203:;; neltst is number of elements to generate
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204:;; before we overlap previous elements
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205:nelts set neltst ;;counter
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206:xlt&dn equ $ ;;translate table
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207: rept sectors ;;once for each sector
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208: if sectors<256
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209: ddb %nxtsec+(fsc)
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210: else
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211: ddw %nxtsec+(fsc)
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212: endif
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213:nxtsec set nxtsec+(skf)
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214: if nxtsec>=sectors
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215:nxtsec set nxtsec-sectors
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216: endif
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217:nelts set nelts-1
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218: if nelts = 0
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219:nxtbas set nxtbas+1
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220:nxtsec set nxtbas
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221:nelts set neltst
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222: endif
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223: endm
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224: endif ;;end of nul fac test
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225: endif ;;end of nul bls test
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226: endm
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227:;
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228:defds macro lab,space
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229:lab: ds space
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230: endm
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231:;
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232:lds macro lb,dn,val
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233: defds lb&dn,%val&dn
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234: endm
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235:;
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236:endef macro
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237:;; generate the necessary ram data areas
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238:begdat equ $
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239:dirbuf: ds 128 ;directory access buffer
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240:dsknxt set 0
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241: rept ndisks ;;once for each disk
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242: lds alv,%dsknxt,als
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243: lds csv,%dsknxt,ccs
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244:dsknxt set dsknxt+1
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245: endm
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246:enddat equ $
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247:datsiz equ $-begdat
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248:;; db 0 at this point forces hex record
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249: endm
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.nx appg
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