【正文】 DSEG MOV DS， AX MOV AL， DATA CALL BHTOA PUSH AX MOV DL， AH MOV AH， 2 INT 21H POP DX INT 21H MOV AX， 4C00H INT 21H CSEG ENDS END START 子程序能直接或間地調(diào)用自身稱為遞歸調(diào)用，具有遞歸調(diào)用性質(zhì)的子程序稱為遞歸子程序。遞歸子程序一般用 。即每個(gè)遞歸函數(shù)有一個(gè)非遞歸終值，遞歸過程 (子程序 )一旦求得該值， ，其值可由函數(shù)中的 舉例 ：階乘函數(shù)，對(duì)于任一個(gè)大于等于 0的正整數(shù) N，其函數(shù)值定義為： 1 (N=0) FACT(N)= N*FACT(N1) (N0) { 算 法 (1)測(cè)試 N=0嗎？是，則令 FACT(N)=1，返回； (2)保存 N，并令 N=N1，調(diào)用自身求得 FACT(N1)； (3)順序取出保存的 N值（后保存的先取出）； (4)計(jì)算 FACT(N)=N*FACT(N1)，并返回。 1:。***** ***** 2:FACT PROC NEAR 3: AND BX,BX 4: JZ FACT1 5: PUSH BX 6: DEC BX 7: CALL FACT 8:F: POP BX 9: MUL BX 10: RET 11:FACT1: MOV AX,1 12: RET 13:FACT ENDP 舉例：求 4！ SSEG SEGMENT SKTOP DB 20H DUP (0) SSEG ENDS CSEG SEGMENT ASSUME CS:CSEG FACT PROC NEAR AND BX,BX JZ FACT1 PUSH BX DEC BX CALL FACT aabb POP BX MUL BX RET FACT1: MOV AX,1 RET FACT ENDP MIAN: MOV AX,SSEG MOV DS,AX ① MOV SP,SIZE SKTOP MOV BX,4 ② CALL FACT xxyy NOP CSEG ENDS END MAIN 0BH0D H0E H0FH10H1 1H12H13H14H15H16H17H18H19H1A H1BH1CH1D H1E H1FH20H ← SP執(zhí)行指令 ① 后 舉例：求 4！ SSEG SEGMENT SKTOP DB 20H DUP (0) SSEG ENDS CSEG SEGMENT ASSUME CS:CSEG FACT PROC NEAR AND BX,BX JZ FACT1 ③ PUSH BX DEC BX ④ CALL FACT aabb POP BX MUL BX ⑤ RET FACT1: MOV AX,1 ⑥ RET FACT ENDP MIAN: MOV AX,SSEG MOV DS,AX ① MOV SP,SIZE SKTOP MOV BX,4 ② CALL FACT xxyy NOP CSEG ENDS END MAIN 0BH0D H0E H0FH10H1 1H12H13H14H15H16H17H18H19H1A H1BH1CH1D H1E H yy ← SP1FH Xx20H執(zhí)行指令 ② 后 BX=4 AX=? SP=1EH 舉例：求 4！ SSEG SEGMENT SKTOP DB 20H DUP (0) SSEG ENDS CSEG SEGMENT ASSUME CS:CSEG FACT PROC NEAR AND BX,BX JZ FACT1 ③ PUSH BX DEC BX ④ CALL FACT aabb POP BX MUL BX ⑤ RET FACT1: MOV AX,1 ⑥ RET FACT ENDP MIAN: MOV AX,SSEG MOV DS,AX ① MOV SP,SIZE SKTOP MOV BX,4 ② CALL FACT xxyy NOP CSEG ENDS END MAIN 0BH0D H0E H0FH10H1 1H12H13H14H15H16H17H18H19H1A H1BH1CH 04H ← SP1D H 001E H yy1FH Xx20H執(zhí)行指令 ③ 后 BX=4 AX=? SP=1CH 舉例：求 4！ SSEG SEGMENT SKTOP DB 20H DUP (0) SSEG ENDS CSEG SEGMENT ASSUME CS:CSEG FACT PROC NEAR AND BX,BX JZ FACT1 ③ PUSH BX DEC BX ④ CALL FACT aabb POP BX MUL BX ⑤ RET FACT1: MOV AX,1 ⑥ RET FACT ENDP MIAN: MOV AX,SSEG MOV DS,AX ① MOV SP,SIZE SKTOP MOV BX,4 ② CALL FACT xxyy NOP CSEG ENDS END MAIN 0BH0D H0E H0FH10H1 1H12H13H14H15H16H17H18H19H1A H bb ← SP1BH aa1CH 04H1D H 001E H yy1FH Xx20H執(zhí)行指令 ④ 后 BX=3 AX=? SP=1AH 舉例：求 4！ SSEG SEGMENT SKTOP DB 20H DUP (0) SSEG ENDS CSEG SEGMENT ASSUME CS:CSEG FACT PROC NEAR AND BX,BX JZ FACT1 ③ PUSH BX DEC BX ④ CALL FACT aabb POP BX MUL BX ⑤ RET FACT1: MOV AX,1 ⑥ RET FACT ENDP MIAN: MOV AX,SSEG MOV DS,AX ① MOV SP,SIZE SKTOP MOV BX,4 ② CALL FACT xxyy NOP CSEG ENDS END MAIN 0BH0D H0E H0FH10H1 1H12H13H14H15H16H17H18H 03H ← SP19H 00H1A H bb1BH aa1CH 04H1D H 001E H yy1FH Xx20H再執(zhí)行指令 ③ 后 BX=3 AX=? SP=18H 舉例：求 4！ SSEG SEGMENT SKTOP DB 20H DUP (0) SSEG ENDS CSEG SEGMENT ASSUME CS:CSEG FACT PROC NEAR AND BX,BX JZ FACT1 ③ PUSH BX DEC BX ④ CALL FACT aabb POP BX MUL BX ⑤ RET FACT1: MOV AX,1 ⑥ RET FACT ENDP MIAN: MOV AX,SSEG MOV DS,AX ① MOV SP,SIZE SKTOP MOV BX,4 ② CALL FACT xxyy NOP CSEG ENDS END MAIN 0BH0D H0E H0FH10H1 1H12H13H14H15H16H bb ← SP17H aa18H 03H19H 00H1A H bb1BH aa1CH 04H1D H 001E H yy1FH Xx20H再執(zhí)行指令 ④ 后 BX=2 AX=? SP=16H 舉例：求 4！ SSEG SEGMENT SKTOP DB 20H DUP (0) SSEG ENDS CSEG SEGMENT ASSUME CS:CSEG FACT PROC NEAR AND BX,BX JZ FACT1 ③ PUSH BX DEC BX ④ CALL FACT aabb POP BX MUL BX ⑤ RET FACT1: MOV AX,1 ⑥ RET FACT ENDP MIAN: MOV AX,SSEG MOV DS,AX ① MOV SP,SIZE SKTOP MOV BX,4 ② CALL FACT xxyy NOP CSEG ENDS END MAIN 0BH0D H0E H0FH10H1 1H12H13H14H 02H ← SP15H 00H16H bb17H aa18H 03H19H 00H1A H bb1BH aa1CH 04H1D H 001E H yy1FH Xx20H再執(zhí)行指令 ③ 后 BX=2 AX=? SP=14H 舉例：求 4！ SSEG SEGMENT SKTOP DB 20H DUP (0)