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(Assume. top. of. stack. is. at. level. 1. b. elo. w.). Calling. program. LDR. R0,POINTER. Push. NUM1. –. STR. R0,[R13,#. 4]!. on. stack. LDR. R0,N. Push. n. –. STR. R0,[R13,#. 4]!. on. stack. BL. LIST. ADD. LDR. R0,[R13,#4]. Mo. v. e. the. sum. in. to.

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  1. (Assume top of stack is at level 1 b elo w.) Calling program LDR R0,POINTER Push NUM1 – STR R0,[R13,# 4]! on stack. LDR R0,N Push n – STR R0,[R13,# 4]! on stack. BL LIST ADD LDR R0,[R13,#4] Mo v e the sum in to STR R0,SUM memory lo cation SUM. ADD R13,R13,#8 Remo v e parameters from stack. . . . Subroutine – LIST ADD STMFD R13!, { R0 R3,R14 } Sa v e registers. LDR R1,[R13,#20] Load parameters LDR R2,[R13,#24] from stack. MO V R0,#0 LOOP LDR R3,[R2],#4 ADD R0,R0,R3 SUBS R1,R1,#1 BGT LOOP STR R0,[R13,#24] Place sum on stack. – LDMFD R13!, { R0 R3,R15 } Restore registers and return. (a) Calling program and subroutine [R0]  Lev el 3 [R1] [R2] [R3] Return Address Lev el 2  n NUM1  Lev el 1 (b) T op of stack at various times Figure 3.11. Program of Figure 3.7 written as an ARM subroutine; parameters passed on the stack.

  2. Memory lo cation Instructions Commen ts Calling program . . . 2000 LDR R10,P ARAM2 Place parameters on stac k. – 2004 STR R10,[SP, # 4]! 2008 LDR R10,PARAM1 – 2012 STR R10,[SP, # 4]! 2016 BL SUB1 2020 LDR R10,[SP] Store SUB1 result. 2024 STR R10,RESUL T 2028 ADD SP, SP, #8 Remo v e parameters from stac k. 2032 next instruction . . . First subroutine – 2100 SUB1 STMFD SP!, { R0 R3,FP, LR } Sa v e registers. 2104 ADD FP, SP ,#16 Load frame p oin ter. 2108 LDR R0,[FP, #8] Load parameters. 2112 LDR R1,[FP, #12] . . . LDR R2,P ARAM3 Place parameter on stac k. – STR R2,[SP, # 4]! 2160 BL SUB2 2164 LDR R2,[SP],#4 P op SUB2 result in to R2. . . . STR R3,[FP, #8] Place result on stac k. – LDMFD SP!, { R0 R3,FP, PC } Restore registers and return. Second subroutine 3000 SUB2 STMFD SP!, { R0,R1,FP, LR } Sa v e registers. ADD FP, SP, #8 Load frame p oin ter. LDR R0,[FP, #8] Load parameter. . . . STR R1,[FP, #8] Place result on stac k. LDMFD SP!, { R0,R1,FP, PC } Restore registers and return. Figure 3.12. Nested subroutines in ARM assembly language.

  3. – (j = n 1; j > 0; j = j 1) for – – { ( k = j 1; k > = 0; k = k 1 ) for { (LIST[ k ] > LIST[ j ]) if { TEMP = LIST[ k ]; LIST[ k ] = LIST[ j ]; LIST[ j ] = TEMP; } } } (a) C-language program for sorting ADR R4,LIST Load list p oin ter register R4, LDR R10,N and initialize outer lo op base n ADD R2,R4,R10 register R2 to LIST + . ADD R5,R4,#1 Load LIST + 1 in to R5. – OUTER LDRB R0,[R2,# 1]! Load LIST( j ) in to R0. MO V R3,R2 Initialize inner lo op base register – n 1. R3 to LIST + – INNER LDRB R1,[R3,# 1]! Load LIST( k ) in to R1. CMP R1,R0 Compare LIST( k ) to LIST( j ). STR GTB R1,[R2] If LIST( k ) > LIST( j ), in terc hange STR GTB R0,[R3] LIST( k ) and LIST( j ), and MO V GT R0,R1 mo v e (new) LIST( j ) in to R0. CMP R3,R4 If k > 0, rep eat BNE INNER inner lo op. CMP R2,R5 If j > 1, rep eat BNE OUTER outer lo op. (b) ARM program implementation Figure 3.15. An ARM byte-sorting program.

  4. (Assume top of stac k is at lev el 1 b elo w.) Calling program – MO VE.L #NUM1, (A7) Push parameters on to stac k. – MO VE.L N, (A7) BSR LIST ADD MO VE.L 4(A7),SUM Sa v e result. ADDI.L #8,A7 Restore top of stac k. . . . Subroutine – – LIST ADD MO VEM.L D0 D1/A2, (A7) Sa v e registers D0, D1, and A2. MO VE.L 16(A7),D1 Initialize coun ter to n . SUBQ.L #1,D1 Adjust coun t to use DBRA. MO VEA.L 20(A7),A2 Initialize p oin ter to the list. CLR.L D0 Initialize sum to 0. LOOP ADD.W (A2)+,D0 Add en try from list. DBRA D1,LOOP MO VE.L D0,20(A7) Put result on the stac k. – MO VEM.L (A7)+,D0 D1/A2 Restore registers. R TS (a) Calling program and subroutine [D0] Lev el 3  [D1] [A2] Return address Lev el 2  n NUM1 Lev el 1  (b) Stack contents at different times Figure 3.29. Program of Figure 3.26 written as a 68000 subroutine, parameters passed on the stack.

  5. Memory lo cation Instructions Comments Calling program . . . – 2000 MO VE.L P ARAM2, (A7) Place parameters on stack. – 2006 MO VE.L P ARAM1, (A7) 2012 BSR SUB1 2014 MO VE.L (A7),RESUL T Store result. 2020 ADDI.L #8,A7 Restore stac k lev el. 2024 next instruction . . . First subroutine 2100 SUB1 LINK A6,#0 Set frame p oin ter. – – 2104 MO VEM.L D0 D2/A0, (A7) Sa v e registers. MO VEA.L 8(A6),A0 Load parameters. MO VE.L 12(A6),D0 . . . – MO VE.L P ARAM3, (A7) Place a parameter on stack. 2160 BSR SUB2 2164 MO VE.L (A7)+,D1 P op result from SUB2 in to D1. . . . MO VE.L D2,8(A6) Place result on stac k. – MO VEM.L (A7)+,D0 D2/A0 Restore registers. UNLK A6 Restore frame p oin ter. R TS Return. Second subroutine 3000 SUB2 LINK A6,#0 Set frame pointer. – – MO VEM.L D0 D1, (A7) Sa v e registers. MO VE.L 8(A6),D0 Load parameter. . . . MO VE.L D1,8(A6) Place result on stack. – MO VEM.L (A7)+,D0 D1 Restore registers. UNLK A6 Restore frame p oin ter. R TS Return. Figure 3.30. Nested subroutines in 68000 assembly language.

  6.  (j = n 1; j > 0; j = j 1) for   { ( k = j 1; k > = 0; k = k 1 ) for { (LIST[ k ] > LIST[ j ] ) if { TEMP = LIST[ k ]; LIST[ k ] = LIST[ j ]; LIST[ j ] = TEMP; } } } (a) C-language program for sorting MO VEA.L #LIST,A1 P oin ter to the start of the list. MO VE N,D1 Initialize outer lo op SUBQ #1,D1 index j in D1. OUTER MO VE D1,D2 Initialize inner lo op SUBQ #1,D2 index k in D2. MO VE.B (A1,D1),D3 Curren t maxim um v alue in D3.  INNER CMP .B D3,(A1,D2) If LIST( k ) [D3], BLE NEXT do not exc hange. MO VE.B (A1,D2),(A1,D1) In terc hange LIST( k ) MO VE.B D3,(A1,D2) and LIST( j ) and load MO VE.B (A1,D1),D3 new maxim um in to D3. NEXT DBRA D2,INNER Decremen t coun ters k and j SUBQ #1,D1 and branc h bac k BGT OUTER if not finished. (b) 68000 program implementation Figure 3.34. A 68000 byte-sorting program.

  7. Figure 3.38. Compatibility of the IA-32 register structure with earlier Intel processor register structures.

  8. Main memory address doubleword 1000 Base register EBP 1000 * * * * 60 = displacement * * Operand 1060 Operand address (EA) = [EBP] + 60 (a) Base with displacement mode, expressed as [EBP + 60] 1000 Base register EBP 1000 40 * * Index register ESI * * * * 200 = displacement 1200 scale factor = 4 List of 4-byte * * ´ (double w ord) 160 = [Index register] 4 * * data items * * Operand 1360 * * * * * * * * * * * * ´ Operand address (EA) = [EBP] + [ESI] 4 + 200 (b) Base with displacement and index mode, expressed as [EBP + ESI * 4 + 200] Figure 3.39. Examples of addressing modes in the IA-32 architecture.

  9. LEA EBX,NUM1 Initialize base (EBX) and MO V ECX,N coun ter (ECX) registers. MO V EAX,0 Clear accum ulator (EAX) MO V EDI,0 and index (EDI) registers. * ST AR T ADD: ADD EAX,[EBX + EDI 4] Add next n um b er in to EAX. INC EDI Incremen t index register. DEC ECX Decremen t coun ter register. JG ST AR T ADD Branc h bac k if [ECX] > 0. MO V SUM,EAX Store sum in memory . (a) Straightforward approach LEA EBX,NUM1 Load base register EBX and – SUB EBX,4 adjust to hold NUM1 4. MO V ECX,N Initialize coun ter/index (ECX). MO V EAX,0 Clear the accum ulator (EAX). * ST AR T ADD: ADD EAX,[EBX + ECX 4] Add next n um b er in to EAX. LOOP ST AR T ADD Decremen t ECX and branc h bac k if [ECX] > 0. MO V SUM,EAX Store sum in memory . (b) More compact program Figure 3.40. IA-32 program for adding numbers.

  10. Calling program . . . LEA EBX,NUM1 Load parameters MO V ECX,N in to EBX,ECX. CALL LIST ADD Branc h to subroutine. MO V SUM,EAX Store sum in to memory . . . . Subroutine LIST ADD: PUSH EDI Sa v e EDI. MO V EDI,0 Use EDI as index register. MO V EAX,0 Use EAX as accum ulator register. * ST AR T ADD: ADD EAX, [EBX + EDI 4] Add next n um b er. INC EDI Incremen t index. DEC ECX Decremen t coun ter. JG STARTADD Branc h bac k if [ECX] > 0. POP EDI Restore EDI. RET Branc h bac k to Calling program. (a) Calling program and subroutine [EDI] ESP  Return Address Old TOS (b) Stack contents after saving EDI in subroutine Figure 3.45. Program of Figure 3.40a written as an IA-32 subroutine; parameters passed through registers.

  11. (Assume top of stac k is at lev el 1 b elo w.) Calling program PUSH OFFSET NUM1 Push parameters on to the stack. PUSH N CALL LIST ADD Branc h to the subroutine. ADD ESP ,4 Remo v e n from the stack. POP SUM P op the sum in to SUM. . . . Subroutine LIST ADD: PUSH EDI Sa v e EDI and use MO V EDI,0 as index register. PUSH EAX Sa v e EAX and use as MO V EAX,0 accummulator register. PUSH EBX Sa v e EBX and load MO V EBX,[ESP+20] address NUM1. PUSH ECX Sa v e ECX and MO V ECX,[ESP+20] load count n . * ST AR T ADD: ADD EAX,[EBX+EDI 4] Add next n umber. INC EDI Incremen t index. DEC ECX Decremen t coun ter. JG ST AR T ADD Branc h bac k if not done. MO V [ESP+24],EAX Ov erwrite NUM1 in stac k with sum. POP ECX Restore registers. POP EBX POP EAX POP EDI RET Return. (a) Calling program and subroutine  [ECX] Lev el 3 [EBX] [EAX] [EDI] Return Address  Lev el 2 n NUM1  Lev el 1 (b) Stack contents at different times Figure 3.46. Program of Figure 3.40a written as an IA-32 subroutine; parameters passed on the stack.

  12. Address Instructions Commen ts Calling program . . . 2000 PUSH P ARAM2 Place parameters 2006 PUSH P ARAM1 on stac k. 2012 CALL SUB1 2017 POP RESUL T Store result. ADD ESP ,4 Restore stac k lev el. . . . First subroutine 2100 SUB1: PUSH EBP Sa v e frame p oin ter register. MO V EBP ,ESP Load frame p oin ter. PUSH EAX Sa v e registers. PUSH EBX PUSH ECX PUSH ED X MO V EAX,[EBP+8] Get first parameter. MO V EBX,[EBP+12] Get second parameter. . . . PUSH P ARAM3 Place parameter on stac k. 2160 CALL SUB2 2165 POP ECX P op SUB2 result in to ECX. . . . MO V [EBP+8],ED X Place answ er on stac k. POP ED X Restore registers. POP ECX POP EBX POP EAX POP EBP Restore frame p oin ter register. RET Return to Main program. Second subroutine 3000 SUB2: PUSH EBP Sa v e frame p oin ter register. MO V EBP ,ESP Load frame p oin ter. PUSH EAX Sa v e registers. PUSH EBX MO V EAX,[EBP+8] Get parameter. . . . MO V [EBP+8],EBX Place SUB2 result on stac k. POP EBX Restore registers. POP EAX POP EBP Restore frame p oin ter register. RET Return to first subroutine. Figure 3.47. Nested subroutines in IA-32 assembly language.

  13. – (j = n 1; j > 0; j = j 1) for – – { ( k = j 1; k > = 0; k = k 1 ) for { (LIST[ k ] > LIST[ j ]) if { TEMP = LIST[ k ]; LIST[ k ] = LIST[ j ]; LIST[ j ] = TEMP; } } } (a) C-language program for sorting LEA EAX,LIST Load list p oin ter base MO V EDI,N register (EAX), and initialize DEC EDI outer lo op index register – (EDI) to j = n 1. OUTER: MO V ECX,EDI Initialize inner lo op index – DEC ECX register (ECX) to k = j 1. MO V DL,[EAX + EDI] Load LIST(j) in to register DL. INNER: CMP [EAX + ECX],DL Compare LIST(k) to LIST(j).  JLE NEXT If LIST(k) LIST(j), go to next lo w er k index en try; X CHG [EAX + ECX],DL Otherwise, in terc hange LIST(k) and LIST(j), lea ving MO V [EAX + EDI],DL new LIST(j) in DL. NEXT: DEC ECX Decremen t inner lo op index k. JGE INNER Rep eat or terminate inner lo op. DEC EDI Decremen t outer lo op index j. JG OUTER Rep eat or terminate outer lo op. (b) IA-32 program implementation Figure 3.50. An IA-32 byte-sorting program using straight-selection sort.

  14. T ABLE 3.1 ARM index addressing modes Name Assembler syntax Addr essing function W ith immediate of fset: Pre-inde x ed [R n , #of fset] EA = [R n ] + of fset Pre-inde x ed with writeback [R n , #of fset]! EA = [R n ] + of fset;  R n [R n ] + of fset Post-inde x ed [R n ], #of fset EA = [R n ];  R n [R n ] + of fset W ith of fset magnitude in R m :   Pre-inde x ed [R n , R m , shift] EA = [R n ] [R m ] shifted Pre-inde x ed   with writeback [R n , R m , shift]! EA = [R n ] [R m ] shifted;   R n [R n ] [R m ] shifted  Post-inde x ed [R n ], R m , shift EA = [R n ];   R n [R n ] [R m ] shifted Relati v e Location EA = Location (Pre-inde x ed with = [PC] + of fset immediate of fset) EA = ef fecti v e address of fset = a signed number contained in the instruction shift = direction #inte ger where direction is LSL for left shift or LSR for right shift, and inte ger is a 5-bit unsigned number specifying the shift amount  R m = the of fset magnitude in re gister R m can be added to or subtracted from the contents of base re gister R n

  15. T able 3.2 68000 addressing modes syn tax Name Assem bler Addressing function Immediate #V alue Op erand = V alue Absolute Short V alue EA = Sign Extended WV alue Absolute Long V alue EA = V alue Register Rn EA = R n that is, Op erand = [R ] n Register Indirect (An) EA = [A ] n Autoincremen t (An)+ EA = [A ]; n Incremen t A n – Auto decremen t (An) Decremen t A ; n EA = [A ] n Indexed basic WV alue(An) EA = WV alue + [A ] n Indexed full BV alue(An,Rk.S) EA = BV alue + [A ] +[R ] n k Relativ e basic WV alue(PC) EA = WV alue + [PC] or Lab el Relativ e full BV alue(PC,Rk.S) EA = BV alue + [PC] + [R ] k or Lab el (Rk) EA = effectiv e address V alue = a n um b er giv en either explicitly or represen ted b y a lab el BV alue = an 8-bit V alue WV alue = a 16-bit V alue A = an address register n R = an address or a data register n S = a size indicator: W for sign-extended 16-bit w ord and L for 32-bit long w ord

  16. T able 3.3 IA-32 addressing modes Name Assem bler syn tax Addressing function Immediate V alue Op erand = V alue Direct Lo cation EA = Lo cation Register Reg EA = Reg that is, Op erand = [Reg] Register indirect [Reg] EA = [Reg] Base with [Reg + Disp] EA = [Reg] + Disp displacemen t  * Index with [Reg EA = [Reg] S + Disp S + Disp] displacemen t  * Base with index [Reg1 + Reg2 S] EA = [Reg1] + [Reg2] S  * Base with index [Reg1 + Reg2 S + Disp] EA = [Reg1] + [Reg2] S + Disp and displacemen t V alue = an 8- or 32-bit signed n um b er Lo cation = a 32-bit address Reg, Reg1, Reg2 = one of the general purp ose registers EAX, EBX, ECX, ED X, ESP , EBP , ESI, EDI, with the exception that ESP cannot be used as an index register Disp = an 8- or 32-bit signed n um b er, except that in the Index with displacemen t mode it can only b e 32 bits. S = a scale factor of 1, 2, 4, or 8

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